Incorporating ReS2 Nanosheet into ZnIn2S4 Nanoflower as Synergistic Z-Scheme Photocatalyst for Highly Effective and Stable Visible-Light-Driven Photocatalytic Hydrogen Evolution and Degradation

Inspired by natural photosynthesis, the visible-light-driven Z-scheme system is very effective and promising for boosting photocatalytic hydrogen production and pollutant degradation. Here, a synergistic Z-scheme photocatalyst is constructed by coupling ReS2 nanosheet and ZnIn2S4 nanoflower and the experimental evidence for this direct Z-scheme heterostructure is provided by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance. Consequently, such a unique nanostructure makes this Z-scheme heterostructure exhibit 23.7 times higher photocatalytic hydrogen production than that of ZnIn2S4 nanoflower. Moreover, the ZnIn2S4/ReS2 photocatalyst is also very stable for photocatalytic hydrogen evolution, almost without activity decay even storing for two weeks. Besides, this Z-scheme heterostructure also exhibits superior photocatalytic degradation rates of methylene blue (1.7 × 10-2 min-1) and mitoxantrone (4.2 × 10-3 min-1) than that of ZnIn2S4 photocatalyst. The ultraviolet-visible absorption spectra, transient photocurrent spectra, open-circuit potential measurement, and electrochemical impedance spectroscopy reveal that the superior photocatalytic performance of ZnIn2S4/ReS2 heterostructure is mostly attributed to its broad and strong visible-light absorption, effective separation of charge carrier, and improved redox ability. This work provides a promising nanostructure design of a visible-light-driven Z-scheme heterostructure to simultaneously promote photocatalytic reduction and oxidation activity.

Near-infrared light-driven biomass conversion

Current photocatalytic technologies mainly rely on the input of high-energy ultraviolet-visible (UV-vis) light to obtain the desired excited states with adequate energy to drive redox reactions, precluding the use of low-energy near-infrared (NIR) light that occupies ~50% of the solar spectrum. Here, we report the efficient utilization of NIR light by coupling the low-energy NIR photons with reactive biomass conversion. A unique mechanism of photothermally synergistic photocatalysis was revealed for the selective biomass conversion under NIR light. Using biomass-derived 5-hydroxymethylfurfural (HMF) conversion as a model reaction, it was found that NIR and UV-vis light featured markedly different reaction patterns. 5-Formyl-2-furancarboxylic acid (FFCA) was almost exclusively produced under NIR light, whereas UV-vis light favored the formation of 2,5-diformylfuran (DFF) as the major product. This work provides a paradigm for sustainable and selective chemical synthesis using the Earth's abundant resources, sunlight and biomass.

Towards the 10-Year Milestone of Monolithic Perovskite/Silicon Tandem Solar Cells

The perovskite/silicon tandem solar cell represents one of the most promising avenues for exceeding the Shockley-Queisser limit for single-junction solar cells at a reasonable cost. Remarkably, its efficiency has rapidly increased from 13.7% in 2015 to 34.6% in 2024. Despite the significant research efforts dedicated to this topic, the "secret" to achieving high-performance perovskite/silicon tandem solar cells seems to be confined to a few research groups. Additionally, the discrepancies in preparation and characterization between single-junction and tandem solar cells continue to impede the transition from efficient single-junction to efficient tandem solar cells. This review first revisits the key milestones in the development of monolithic perovskite/silicon tandem solar cells over the past decade. Then, a comprehensive analysis of the background, advancements, and challenges in perovskite/silicon tandem solar cells is provided, following the sequence of the tandem fabrication process. The progress and limitations of the prevalent stability measurements for tandem devices are also discussed. Finally, a roadmap for designing efficient, scalable, and stable perovskite/silicon tandem solar cells is outlined. This review takes the growth history into consideration while charting the future course of perovskite/silicon tandem research.

Integrating bicarbonate-based microalgal production with alkaline sewage for ocean negative carbon emissions

Using sewage (wastewater) for ocean alkalinity enhancement (OAE) has been considered as one promising ocean negative carbon emissions (ONCE) approach due to its high carbon sequestration efficiency and low environmental risk. To make this process more profitable and sustainable, this perspective proposes to integrate bicarbonate-based microalgal production and sewage alkalinity enhancement for ONCE. In this concept, the spent aqueous alkaline bicarbonate-based microalgal medium is cheap or even free for OAE, while the produced microalgae with high value-added compositions make this process more profitable. To make the proposed idea more efficient and sustainable, the prospects for its future development are also discussed in this opinion article. This perspective provides a novel and practical idea for achieving efficient carbon neutralization and high economic value simultaneously.

Facile Synthesis of Organic-Inorganic Hybrid Heterojunctions of Glycolated Conjugated Polymer-TiO2-X for Efficient Photocatalytic Hydrogen Evolution

The utilization of the organic-inorganic hybrid photocatalysts for water splitting has gained significant attention due to their ability to combine the advantages of both materials and generate synergistic effects. However, they are still far from practical application due to the limited understanding of the interactions between these two components and the complexity of their preparation process. Herein, a facial approach by combining a glycolated conjugated polymer with a TiO2-X mesoporous sphere to prepare high-efficiency hybrid photocatalysts is presented. The functionalization of conjugated polymers with hydrophilic oligo (ethylene glycol) side chains can not only facilitate the dispersion of conjugated polymers in water but also promote the interaction with TiO2-X forming stable heterojunction nanoparticles. An apparent quantum yield of 53.3% at 365 nm and a hydrogen evolution rate of 35.7 mmol h-1 g-1 is achieved by the photocatalyst in the presence of Pt co-catalyst. Advanced photophysical studies based on femtosecond transient absorption spectroscopy and in situ, XPS analyses reveal the charge transfer mechanism at type II heterojunction interfaces. This work shows the promising prospect of glycolated polymers in the construction of hybrid heterojunctions for photocatalytic hydrogen production and offers a deep understanding of high photocatalytic performance by such heterojunction photocatalysts.

Concentrated Solar Light Photoelectrochemical Water Splitting for Stable and High-Yield Hydrogen Production

Photoelectrochemical water splitting is a promising technique for converting solar energy into low-cost and eco-friendly H2 fuel. However, the production rate of H2 is limited by the insufficient number of photogenerated charge carriers in the conventional photoelectrodes under 1 sun (100 mW cm-2) light. Concentrated solar light irradiation can overcome the issue of low yield, but it leads to a new challenge of stability because the accelerated reaction alters the surface chemical composition of photoelectrodes. Here, it is demonstrated that loading Pt nanoparticles (NPs) on single crystalline GaN nanowires (NWs) grown on n+-p Si photoelectrode operates efficiently and stably under concentrated solar light. Although a large number of Pt NPs detach during the initial reaction due to H2 gas bubbling, some Pt NPs which have an epitaxial relation with GaN NWs remain stably anchored. In addition, the stability of the photoelectrode further improves by redepositing Pt NPs on the reacted Pt/GaN surface, which results in maintaining onset potential >0.5 V versus reversible hydrogen electrode and photocurrent density >60 mA cm-2 for over 1500 h. The heterointerface between Pt cocatalysts and single crystalline GaN nanostructures shows great potential in designing an efficient and stable photoelectrode for high-yield solar to H2 conversion.

Review on synthetic approaches and PEC activity performance of bismuth binary and mixed-anion compounds for potential applications in marine engineering

Photoelectrochemical (PEC) technology in marine engineering holds significant importance due to its potential to address various challenges in the marine environment. Currently, PEC-type applications in marine engineering offer numerous benefits, including sustainable energy generation, water desalination and treatment, photodetection, and communication. Finding novel efficient photoresponse semiconductors is of great significance for the development of PEC-type techniques in the marine space. Bismuth-based semiconductor materials possess suitable and tunable bandgap structures, high carrier mobility, low toxicity, and strong oxidation capacity, which gives them great potential for PEC-type applications in marine engineering. In this paper, the structure and properties of bismuth binary and mixed-anion semiconductors have been reviewed. Meanwhile, the recent progress and synthetic approaches were discussed from the point of view of the application prospects. Finally, the issues and challenges of bismuth binary and mixed-anion semiconductors in PEC-type photodetection and hydrogen generation are analyzed. Thus, this perspective will not only stimulate the further investigation and application of bismuth binary and mixed-anion semiconductors in marine engineering but also help related practitioners understand the recent progress and potential applications of bismuth binary and mixed-anion compounds.

Molecular Photoelectrochemical Energy Storage Materials for Coupled Solar Batteries

ConspectusSolar-to-electrochemical energy storage is one of the essential solar energy utilization pathways alongside solar-to-electricity and solar-to-chemical conversion. A coupled solar battery enables direct solar-to-electrochemical energy storage via photocoupled ion transfer using photoelectrochemical materials with light absorption/charge transfer and redox capabilities. Common photoelectrochemical materials face challenges due to insufficient solar spectrum utilization, which restricts their redox potential window and constrains energy conversion efficiency. In contrast, molecular photoelectrochemical energy storage materials are promising for their mechanism of exciton-involved redox reaction that allows for extra energy utilization from hot excitons generated by superbandgap excitation and localized heat after absorption of sub-bandgap photons. This enables more efficient redox reactions with a less restricted redox potentials window and, thus, better utilization of the full solar spectrum. Despite these advantages, practical application remains elusive due to the mismatch between the short lifetime of the charge separation state (μs). This mismatch results in a significant portion of the photogenerated charges recombining before participating in desired electrochemical energy storage reactions, leading to diminished overall efficiency. It is therefore highly important to develop molecular materials with intrinsic prolonged charge separation state and extrinsic effective mass-electron transfer to enable efficient coupled solar batteries for practical applications.In this Account, we begin with an introduction of the general solar-to-electrochemical energy storage concept based on molecular photoelectrochemical energy storage materials, highlighting the advantages of periodic oxidative donor-reductive acceptor porous aggregate structures that have synergistic implications on charge separation state lifetime extension and mass-electron transfer. We then present our earliest trial on the design and application of molecular photoelectrochemical energy storage materials, which stimulated our subsequent studies on tuning electron donor and acceptor structures for enhanced charge separation and diverse photoelectrochemical redox reactions. Moreover, we introduce the best practices in the design and assembly of various coupled solar battery devices, along with our literature contributions and progresses in solar-to-electrochemical energy storage efficiency (ηSES) over nearly the past decade. Finally, we conclude by highlighting the universality of our strategies as essential design principles, spanning from regulating long-lived charge separation states and photocoupled ion transfer processes in molecular materials to the construction of efficient coupled solar batteries. We offer perspectives on the synergy between photovoltage and redox potentials and the practical significance of 3D printing, providing key evaluation indicators for large-scale application. This Account provides molecular level insights for the construction of high-efficiency photoelectrochemical energy storage materials and guidance for practical solar-to-electrochemical energy storage applications.

Advancing BiVO4 Photoanode Activity for Ethylene Glycol Oxidation via Strategic pH Control

The photoelectrochemical (PEC) conversion of organic small molecules offers a dual benefit of synthesizing value-added chemicals and concurrently producing hydrogen (H2). Ethylene glycol, with its dual hydroxyl groups, stands out as a versatile organic substrate capable of yielding various C1 and C2 chemicals. In this study, we demonstrate that pH modulation markedly enhances the photocurrent of BiVO4 photoanodes, thus facilitating the efficient oxidation of ethylene glycol while simultaneously generating H2. Our findings reveal that in a pH = 1 ethylene glycol solution, the photocurrent density at 1.23 V vs. RHE can attain an impressive 7.1 mA cm-2, significantly surpassing the outputs in neutral and highly alkaline environments. The increase in photocurrent is attributed to the augmented adsorption of ethylene glycol on BiVO4 under acidic conditions, which in turn elevates the activity of the oxidation reaction, culminating in the maximal production of formic acid. This investigation sheds light on the pivotal role of electrolyte pH in the PEC oxidation process and underscores the potential of the PEC strategy for biomass valorization into value-added products alongside H2 fuel generation.

Revolutionizing agriculture with nanotechnology: Innovative approaches in fungal disease management and plant health monitoring

Nanotechnology has emerged as a transformative force in modern agriculture, offering innovative solutions to address challenges related to fungal plant diseases and overall agricultural productivity. Specifically, the antifungal activities of metal, metal oxide, bio-nanoparticles, and polymer nanoparticles were examined, highlighting their unique mechanisms of action against fungal pathogens. Nanoparticles can be used as carriers for fungicides, offering advantages in controlled release, targeted delivery, and reduced environmental toxicity. Nano-pesticides and nano-fertilizers can enhance nutrient uptake, plant health, and disease resistance were explored. The development of nanosensors, especially those utilizing quantum dots and plasmonic nanoparticles, promises early and accurate detection of fungal pathogens, a crucial step in timely disease management. However, concerns about their potential toxic effects on non-target organisms, environmental impacts, and regulatory hurdles underscore the importance of rigorous research and impact assessments. The review concludes by emphasizing the significant prospects of nanotechnology in reshaping the future of agriculture but advocates for a balanced approach that prioritizes safety, sustainability, and environmental stewardship.

Graphene Quantum Dots as Hole Extraction and Transfer Layer Empowering Solar Water Splitting of Catalyst-Coupled Zinc Ferrite Nanorods

Despite the narrow band gap energy, the performance of zinc ferrite (ZnFe2O4) as a photoharvester for solar-driven water splitting is significantly hindered due to its sluggish charge transfer and severe charge recombination. This work reports the fabrication of a hybrid nanostructured hydrogenated ZnFe2O4 (ZFO) photoanode with enhanced photoelectrochemical water-oxidation activity through coupling N-doped graphene quantum dots (GQDs) as a hole transfer layer and Co-Pi as a catalyst. The GQDs not only reduce the surface-mediated nonradiative electron-hole pair recombination but also induce a built-in interfacial electric field leading to a favorable band alignment at the ZFO/GQDs interface, helping rapid photogenerated hole separation and serving as a conducting hole transfer highway, improve the hole transportation into the Co-Pi catalyst for enhanced water oxidation reaction kinetics. The optimized ZFO/GQD/Co-Pi hybrid photoanode delivers a 23-fold photocurrent enhancement at 1.23 V versus the reversible hydrogen electrode (RHE) and a significant 360 mV reduction in the onset potential, reaching 0.65 VRHE compared with the ZFO photoanode under 1 sun illumination in a neutral electrolytic environment. This investigation underscores the mechanism of synergistic interplay between the hole transport layer and cocatalyst in boosting the solar-illuminated water-splitting activity of the ZFO photoanode.

Prediction of Feasibility of Polaronic OER on (110) Surface of Rutile TiO2

The polaronic effects at the atomic level hold paramount significance for advancing the efficacy of transition metal oxides in applications pertinent to renewable energy. The lattice-distortion mediated localization of photoexcited carriers in the form of polarons plays a pivotal role in the photocatalysis. This investigation focuses on rutile TiO2, an important material extensively explored for solar energy conversion in artificial photosynthesis, specifically targeting the generation of green H2 through photoelectrochemical (PEC) H2O splitting. By employing Hubbard-U corrected and hybrid density functional theory (DFT) methods, we systematically probe the polaronic effects in the catalysis of oxygen evolution reaction (OER) on the (110) surface of rutile TiO2. Theoretical understanding of polarons within the surface, coupled with simulations of OER at distinct titanium (Ti) and oxygen (O) active sites, reveals diverse polaron formation energies within the lattice sites with strong preference for bulk and surface bridge (Ob) oxygen sites. Moreover, we provide the evidence for the facilitative role of polarons in OER. We find that hole polarons situated at the equatorial oxygen sites near the Ti-active site, along with bridge site hole polarons distal from the Ob active site yield a small reduction in OER overpotential by ~0.06 eV and ~0.12 eV, respectively. However, subsurface, equatorial, and bridge site hole polarons significantly reduce the Ti-active site OER overpotential by ~0.4 eV through the peroxo-type oxygen pathway. We also observe that the presence of hole polarons stabilizes the *OH, *O, and *OOH intermediate species compared to the scenario without hole polarons. Overall, this study provides a detailed mechanistic insight into polaron-mediated OER, offering a promising avenue for improving the catalytic activity of transition metal oxide-based photocatalysts catering to renewable energy requisites.

Core-Sheath Heterogeneous Interlocked Conductive Fiber Enables Smart Textile for Personalized Healthcare and Thermal Management

Whereas thermal comfort and healthcare management during long-term wear are essentially required for wearable system, simultaneously achieving them remains challenge. Herein, a highly comfortable and breathable smart textile for personal healthcare and thermal management is developed, via assembling stimuli-responsive core-sheath dual network that silver nanowires(AgNWs) core interlocked graphene sheath induced by MXene. Small MXene nanosheets with abundant groups is proposed as a novel "dispersant" to graphene according to "like dissolves like" theory, while simultaneously acting as "cross-linker" between AgNWs and graphene networks by filling the voids between them. The core-sheath heterogeneous interlocked conductive fiber induced by MXene "cross-linking" exhibits a reliable response to various mechanical/electrical/light stimuli, even under large mechanical deformations(100%). The core-sheath conductive fiber-enabled smart textile can adapt to movements of human body seamlessly, and convert these mechanical deformations into character signals for accurate healthcare monitoring with rapid response(440 ms). Moreover, smart textile with excellent Joule heating and photothermal effect exhibits instant thermal energy harvesting/storage during the stimuli-response process, which can be developed as self-powered thermal management and dynamic camouflage when integrated with phase change and thermochromic layer. The smart fibers/textiles with core-sheath heterogeneous interlocked structures hold great promise in personalized healthcare and thermal management.

Bio-Inspired Ultrathin Perfect Absorber for High-Performance Photothermal Conversion

Ultrathin perfect absorber (UPA) enables efficient photothermal conversion (PC) in renewable chemical and energy systems. However, it is challenging so far to obtain efficient absorption with thickness significantly less than the wavelength, especially considering the common view that an ultrathin film can absorb at most 50% of incident light. Here, a highly light-absorbing and mechanically stable UPA is reported by learning from the honeycomb mirror design of the crab compound eyes. With the hollow apertures enclosed by the self-supporting ultrathin film of reduced graphene oxide and gold nanoparticles, the absorber achieves spoof-plasmon enhanced broadband absorption in solar spectrum and low radiative decay in infrared. Specifically, a strong absorption (87%) is realized by the apertures with cross-section thickness of 1/20 of the wavelength, which is 7.3 times stronger than a planar counterpart with the identical material. Its high PC efficiency up to 64%, with hot-electron temperature as high as 2344 K, is also experimentally demonstrated. Utilizing its low thermal mass nature, a high-speed visible-to-infrared converter is constructed. The absorber can enable high-performance PC processes for future interfacial catalysis and photon-detection.

Carbon Nanotubes as a Solid-State Electron Mediator for Visible-Light-Driven Z-Scheme Overall Water Splitting

So-called Z-scheme systems, which typically comprise an H2 evolution photocatalyst (HEP), an O2 evolution photocatalyst (OEP), and an electron mediator, represent a promising approach to solar hydrogen production via photocatalytic overall water splitting (OWS). The electron mediator transferring photogenerated charges between the HEP and OEP governs the performance of such systems. However, existing electron mediators suffer from low stability, corrosiveness to the photocatalysts, and parasitic light absorption. In the present work, carbon nanotubes (CNTs) were shown to function as an effective solid-state electron mediator in a Z-scheme OWS system. Based on the high stability and good charge transfer characteristics of CNTs, this system exhibited superior OWS performance compared with other systems using more common electron mediators. The as-constructed system evolved stoichiometric amounts of H2 and O2 at near-ambient pressure with a solar-to-hydrogen energy conversion efficiency of 0.15%. The OWS reaction was also promoted in the case that this CNT-based Z-scheme system was immobilized on a substrate. Hence, CNTs are a viable electron mediator material for large-scale Z-scheme OWS systems.

Conjugated Polymer/Recombinant Escherichia coli Biohybrid Systems for Photobiocatalytic Hydrogen Production

Biohybrid photocatalysts are composite materials that combine the efficient light-absorbing properties of synthetic materials with the highly evolved metabolic pathways and self-repair mechanisms of biological systems. Here, we show the potential of conjugated polymers as photosensitizers in biohybrid systems by combining a series of polymer nanoparticles with engineered Escherichia coli cells. Under simulated solar light irradiation, the biohybrid system consisting of fluorene/dibenzo [b,d]thiophene sulfone copolymer (LP41) and recombinant E. coli (i.e., a LP41/HydA BL21 biohybrid) shows a sacrificial hydrogen evolution rate of 3.442 mmol g-1 h-1 (normalized to polymer amount). It is over 30 times higher than the polymer photocatalyst alone (0.105 mmol g-1 h-1), while no detectable hydrogen was generated from the E. coli cells alone, demonstrating the strong synergy between the polymer nanoparticles and bacterial cells. The differences in the physical interactions between synthetic materials and microorganisms, as well as redox energy level alignment, elucidate the trends in photochemical activity. Our results suggest that organic semiconductors may offer advantages, such as solution processability, low toxicity, and more tunable surface interactions with the biological components over inorganic materials.

Advanced Anti-Icing Strategies and Technologies by Macrostructured Photothermal Storage Superhydrophobic Surfaces

Water is the source of life and civilization, but water icing causes catastrophic damage to human life and diverse industrial processes. Currently, superhydrophobic surfaces (inspired by the lotus effect) aided anti-icing attracts intensive attention due to their energy-free property. Here, recent advances in anti-icing by design and functionalization of superhydrophobic surfaces are reviewed. The mechanisms and advantages of conventional, macrostructured, and photothermal superhydrophobic surfaces are introduced in turn. Conventional superhydrophobic surfaces, as well as macrostructured ones, easily lose the icephobic property under extreme conditions, while photothermal superhydrophobic surfaces strongly rely on solar illumination. To address the above issues, a potentially smart strategy is found by developing macrostructured photothermal storage superhydrophobic (MPSS) surfaces, which integrate the functions of macrostructured superhydrophobic materials, photothermal materials, and phase change materials (PCMs), and are expected to achieve all-day anti-icing in various fields. Finally, the latest achievements in developing MPSS surfaces, showcasing their immense potential, are highlighted. Besides, the perspectives on the future development of MPSS surfaces are provided and the problems that need to be solved in their practical applications are proposed.

Promoting Water Oxidation by Proton Acceptable Groups Surrounding Catalyst on Electrode Surface

Large-scale hydrogen production through water splitting represents an optimal approach for storing sustainable but intermittent energy sources. However, water oxidation, a complex and sluggish reaction, poses a significant bottleneck for water splitting efficiency. The impact of outer chemical environments on the reaction kinetics of water oxidation catalytic centers remains unexplored. Herein, chemical environment impacts were integrated by featuring methylpyridinium cation group (Py+) around the classic Ru(bpy)(tpy) (bpy=2,2'-bipyridine, tpy=2,2' : 6',2''-terpyridine) water oxidation catalyst on the electrode surface via electrochemical co-polymerization. The presence of Py+ groups could significantly enhance the turnover frequencies of Ru(bpy)(tpy), surpassing the performance of typical proton acceptors such as pyridine and benzoic acid anchored around the catalyst. Mechanistic investigations reveal that the flexible internal proton acceptor anions induced by Py+ around Ru(bpy)(tpy) are more effective than conventionally anchored proton acceptors, which promoted the rate-determining proton transfer process and enhanced the rate of water nucleophilic attack during O-O bond formation. This study may provide a novel perspective on achieving efficient water oxidation systems by integrating cations into the outer chemical environments of catalytic centers.

Advances in the structural engineering of layered bismuth-based semiconductors for visible light-driven photocatalytic water splitting

Hydrogen production via the photocatalytic water splitting reaction on semiconductors presents a promising avenue to directly achieve solar energy conversion and storage. Bismuth-based semiconductors with layered structures, a hierarchical arrangement of components stacked in the form of two-dimensional extended layers where the atoms within each layer are typically strongly bonded, while the interactions between the layers are relatively weak, have emerged as an important series of photocatalyst candidates. In this review, we focus on the new emerging layered bismuth-based semiconductors with structures in Sillén, Aurivillius, Sillén-Aurivillius and bismuth chromate systems primarily employed in the photocatalytic water splitting reaction. From a crystal structure-oriented view, we delve into discussions on how the component and unit of a crystal structure influence the intrinsic properties, including light absorption and photogenerated charge transfer and separation, of materials as well as the corresponding photocatalytic performance of the water splitting reaction. The strategies for modulating the ferroelectricity and surface modification of these layered bismuth-based semiconductors are also involved. We also discuss the limitations of these materials accompanied by a forward-looking perspective, and we hope to provide some insights from the view of rational material design and engineering for the fabrication of high-efficiency photocatalytic water splitting systems.

Intermolecular Proton-Coupled Electron Transfer Reactivity from a Persistent Charge-Transfer State for Reductive Photoelectrocatalysis

Interest in applying proton-coupled electron transfer (PCET) reagents in reductive electro- and photocatalysis requires strategies that mitigate the competing hydrogen evolution reaction. Photoexcitation of a PCET donor to a charge-separated state (CSS) can produce a powerful H-atom donor capable of being electrochemically recycled at a comparatively anodic potential corresponding to its ground state. However, the challenge is designing a mediator with a sufficiently long-lived excited state for bimolecular reactivity. Here, we describe a powerful ferrocene-derived photoelectrochemical PCET mediator exhibiting an unusually long-lived CSS (τ ∼ 0.9 μs). In addition to detailed photophysical studies, proof-of-concept stoichiometric and catalytic proton-coupled reductive transformations are presented, which illustrate the promise of this approach.

Enabling Self-Adaptive Water-Energy-Balance of Photothermal Water Diode Evaporator: Dynamically Maximizing Energy Utilization Under the Ever-Changing Sunlight

Maintaining a match between input solar energy and required energy by water supply management is key to achieving efficient interfacial solar-driven evaporation (ISDE). In practice, the solar radiation flux is constantly changing throughout the day, so keeping a dynamic water-energy-balance of ISDE is a big challenge. Herein, a photothermal water diode (WD) evaporator concept is proposed by an integrated hydrophilic/hydrophobic Janus absorber to overcome the issue. Due to the unique unidirectional water transport properties induced by asymmetric wettability, a self-adaptive balance between photothermal energy input and water uptake is established, thus realizing the energy matching and utilization maximization. The experimental and simulation results exhibit that with the increase of sunlight intensity, the water supply speed is significantly accelerated due to the dynamic management and self-regulation on water replenishment. Therefore, an excellent evaporation rate of up to 2.14 kg m-2 h-1 with a high efficiency of 93.7% under 1 sun illumination is achieved. This water diode engineering with Janus wettability provides a novel strategy and extends the path for designing solar evaporation systems with diverse water supply properties, which shows great potential in different environmental conditions.

Surface photovoltage microscopy for mapping charge separation on photocatalyst particles

Solar-driven photocatalytic reactions offer a promising route to clean and sustainable energy, and the spatial separation of photogenerated charges on the photocatalyst surface is the key to determining photocatalytic efficiency. However, probing the charge-separation properties of photocatalysts is a formidable challenge because of the spatially heterogeneous microstructures, complicated charge-separation mechanisms and lack of sensitivity for detecting the low density of separated photogenerated charges. Recently, we developed surface photovoltage microscopy (SPVM) with high spatial and energy resolution that enables the direct mapping of surface-charge distributions and quantitative assessment of the charge-separation properties of photocatalysts at the nanoscale, potentially providing unprecedented insights into photocatalytic charge-separation processes. Here, this protocol presents detailed procedures that enable researchers to construct the SPVM instruments by integrating Kelvin probe force microscopy with an illumination system and the modulated surface photovoltage (SPV) approach. It then describes in detail how to perform SPVM measurements on actual photocatalyst particles, including sample preparation, tuning of the microscope, adjustment of the illuminated light path, acquisition of SPVM images and measurements of spatially resolved modulated SPV signals. Moreover, the protocol also includes sophisticated data analysis that can guide non-experts in understanding the microscopic charge-separation mechanisms. The measurements are ordinarily performed on photocatalysts with a conducting substrate in gases or vacuum and can be completed in 15 h.

Boosted light absorption by WO3-x/Ag/PbS heterostructure for high-efficiency interfacial solar steam generation

Interfacial solar steam generation is considered a promising approach to address energy and drinking water shortages. However, designing efficient light-absorbing and photothermal-converting materials remains challenging. In this study, we describe a detailed method for synthesising a three-dimensional (3D) hierarchical oxygen defect-rich WO3/Ag/PbS/Ni foam (termed WO3-x/Ag/PbS/NF) composite to realise efficient exciton separation and enhanced photothermal conversion. The 3D heterogeneous ternary photothermal material combines the individual benefits of WO3-x, Ag and PbS, improving charge transfer and promoting photogenerated electron-hole pairs. This enhances light absorption and energy conversion. Theoretical calculations indicate that the increased photothermal conversion efficiency primarily results from the heterojunction between Ag, WO3-x and PbS, facilitating exciton separation and electron transfer. Consequently, the WO3-x/Ag/PbS/NF solar evaporator exhibits exceptional light absorption (98% within the sunlight spectrum), a high evaporation rate of 1.90 kg m-2h-1 under 1 sun and a light-to-heat conversion efficiency of 94%. The WO3-x/Ag/PbS/NF evaporator also exhibits excellent capabilities in seawater desalination and wastewater treatment. This approach introduces a synergistic concept for creating novel multifunctional light-absorbing materials suitable for various energy-related applications.

Dissolution Heterogeneity Observed in Anisotropic Ruthenium Dioxide Nanocrystals via Liquid-Phase Transmission Electron Microscopy

Noble metal oxides such as ruthenium dioxide are highly active electrocatalysts for anodic reactions in acidic electrolytes, but dissolution during electrochemical operation impedes wide-scale applications in renewable energy technologies. Improving the fundamental understanding of the dissolution dynamics of application-relevant morphologies such as nanocrystals is critical for the grid-scale implementation of these materials. Herein, we report the nanoscale heterogeneity observed via liquid-phase transmission electron microscopy during ruthenium dioxide nanocrystal dissolution under oxidizing conditions. Single-crystalline ruthenium dioxide nanocrystals enabled the direct observation of dissolution along different crystallographic facets, allowing an unprecedented direct comparison of crystal facet stability. The nanoscale observations revealed substantial heterogeneity in the relative stability of crystallographic facets across different nanocrystals, attributed to the nanoscale strains present in these crystals. These findings highlight the importance of nanoscale heterogeneity in determining macroscale properties such as electrocatalyst stability and provide a characterization methodology that can be integrated into next-generation electrocatalyst discovery efforts.

Bifunctional Electrocatalysts for Overall and Hybrid Water Splitting

Electrocatalytic water splitting driven by renewable electricity has been recognized as a promising approach for green hydrogen production. Different from conventional strategies in developing electrocatalysts for the two half-reactions of water splitting (e.g., the hydrogen and oxygen evolution reactions, HER and OER) separately, there has been a growing interest in designing and developing bifunctional electrocatalysts, which are able to catalyze both the HER and OER. In addition, considering the high overpotentials required for OER while limited value of the produced oxygen, there is another rapidly growing interest in exploring alternative oxidation reactions to replace OER for hybrid water splitting toward energy-efficient hydrogen generation. This Review begins with an introduction on the fundamental aspects of water splitting, followed by a thorough discussion on various physicochemical characterization techniques that are frequently employed in probing the active sites, with an emphasis on the reconstruction of bifunctional electrocatalysts during redox electrolysis. The design, synthesis, and performance of diverse bifunctional electrocatalysts based on noble metals, nonprecious metals, and metal-free nanocarbons, for overall water splitting in acidic and alkaline electrolytes, are thoroughly summarized and compared. Next, their application toward hybrid water splitting is also presented, wherein the alternative anodic reactions include sacrificing agents oxidation, pollutants oxidative degradation, and organics oxidative upgrading. Finally, a concise statement on the current challenges and future opportunities of bifunctional electrocatalysts for both overall and hybrid water splitting is presented in the hope of guiding future endeavors in the quest for energy-efficient and sustainable green hydrogen production.

Efficient Noble-Metal-Free Integration Electrolysis for Solar H2 and Supercapacitor Electrode Coproduction in Acidic Water

Solar driven proton exchange membrane water electrolysis (PEMWE) is of great promise for stable and high-purity H2 production, but often limited by the serious partial loading issue due to the intermittent nature of solar energy, the kinetically sluggish oxygen evolution reaction (OER) and the usage of noble metal-based anodes (e. g., Pt, Ir, and Ru). Herein, we report an efficient integrated water electrolysis by replacing OER with favorable pyrrole electrooxidation polymerization for H2 generation in acidic solutions, wherein nonprecious Co2P and carbon cloth (CC) served as cathode and anode, respectively. A voltage of only 1.0 V was needed to afford 10 mA cm-2, 590 mV smaller than that in traditional PEMWE based on noble Pt/C@RuO2 benchmark couple. Moreover, simple carbonization of the resulting polypyrrole/CC at anode yielded a supercapacitor electrode with a high specific capacitance of 290 F g-1 at 1 A g-1 and robust stability, which then functioned as energy reservoir to alleviate the partial loading issue for coproduction of solar H2 and supercapacitor electrode.

Construction of Embedded Sulfur-Doped g-C3N4/BiOBr S-Scheme Heterojunction for Highly Efficient Visible Light Photocatalytic Degradation of Organic Compound Rhodamine B

Constructing S-scheme heterojunction catalysts is a key challenge in visible-light catalysed degradation of organic pollutants. Most heterojunction materials are reported to face significant obstacles in the separation of photogenerated electron-hole pairs owing to differences in the material size and energy barriers. In this study, sulfur-doped g-C3N4 oxidative-type semiconductor materials are synthesized and then coupled with BiOBr reductive-type semiconductor to form S-g-C3N4/BiOBr S-scheme heterojunction. A strong and efficient internal electric field is established between the two materials, facilitating the separation of photogenerated electron-hole pairs. Notably, in situ XPS proved that after visible light irradiation, Bi3+ is converted into Bi(3+ɑ)+, and a large number of photogenerated holes are produced on the surface of BiOBr, which oxidized and activated H2O into •OH.  •OH cooperated with •O2 - and 1O2 to attack Rhodamine B (RhB) molecules to achieve deep oxidation mineralization. The composite material is designed with a LUMO energy level higher than that of RhB, promoting the sensitization of RhB by injecting photogenerated electrons into the heterojunction, thereby enhancing the photocatalytic performance to 22.44 times that of pure g-C3N4. This study provides a new perspective on the efficient degradation of organic molecules using visible light catalysis.

Highly Elastic, Robust, and Efficient Hydrogel Solar Absorber against Harsh Environmental Impacts

Solar distillation is a promising approach for addressing water scarcity, but relentless stress/strain perturbations induced by wind and waves would inevitably cause structural damage to solar absorbers. Despite notable advances in efficient solar absorbers, there have been no reports of compliant and robust solar absorbers withstanding practical mechanical impacts. Herein, an elastic and robust hydrogel absorber that exhibited a high level of evaporation performance was fabricated by introducing ion-coordinated MXene nanosheets as photothermal conversion units and mechanically enhanced fillers. The ion-coordinated MXene nanosheets acting as strong cross-linking points provided excellent elasticity and robustness to the hydrogel absorber. As a result, the evaporation rate of hydrogel absorber, with a high initial value of 2.61 kg m-2 h-1 under one sun irradiation, remained at 2.15 kg m-2 h-1 under a 100% tensile strain state and 2.40 kg m-2 h-1 after 10 000 stretching-releasing cycles. This continuous and stable water desalination approach provides a promising device for actual seawater distillation.

Light-driven ammonia synthesis under mild conditions using lithium hydride

Photon-driven chemical processes are usually mediated by oxides, nitrides and sulfides whose photo-conversion efficiency is limited by charge carrier recombination. Here we show that lithium hydride undergoes photolysis upon ultraviolet illumination to yield long-lived photon-generated electrons residing in hydrogen vacancies, known as F centres. We demonstrate that photon-driven dehydrogenation and dark rehydrogenation over lithium hydride can be fulfilled reversibly at room temperature, which is about 600 K lower than the corresponding thermal process. As light-driven F centre generation could provide an alternative approach to charge carrier separation to favour chemical transformations that are kinetically or thermodynamically challenging, we show that light-activated lithium hydride cleaves the N≡N triple bond to form a N-H bond under mild conditions. Co-feeding a N2/H2 mixture with low H2 partial pressure leads to photocatalytic ammonia formation at near ambient conditions. This work provides insights into the development of advanced materials and processes for light harvesting and conversion.

Artificial Photosynthesis for Regioselective Reduction of NAD(P)+ to NAD(P)H Using Water as an Electron and Proton Source

In photosynthesis, four electrons and four protons taken from water in photosystem II (PSII) are used to reduce NAD(P)+ to produce NAD(P)H in photosystem I (PSI), which is the most important reductant to reduce CO2. Despite extensive efforts to mimic photosynthesis, artificial photosynthesis to produce NAD(P)H using water electron and proton sources has yet to be achieved. Herein, we report the photocatalytic reduction of NAD(P)+ to NAD(P)H and its analogues in a molecular model of PSI, which is combined with water oxidation in a molecular model of PSII. Photoirradiation of a toluene/trifluoroethanol (TFE)/borate buffer aqueous solution of hydroquinone derivatives (X-QH2), 9-mesityl-10-methylacridinium ion, cobaloxime, and NAD(P)+ (PSI model) resulted in the quantitative and regioselective formation of NAD(P)H and p-benzoquinone derivatives (X-Q). X-Q was reduced to X-QH2, accompanied by the oxidation of water to dioxygen under the photoirradiation of a toluene/TFE/borate buffer aqueous solution of [(N4Py)FeII]2+ (PSII model). The PSI and PSII models were combined using two glass membranes and two liquid membranes to produce NAD(P)H using water as an electron and proton source with the turnover number (TON) of 54. To the best of our knowledge, this is the first time to achieve the stoichiometry of photosynthesis, photocatalytic reduction of NAD(P)+ by water to produce NAD(P)H and O2.

Pivotal Role of Geometry Regulation on O-O Bond Formation Mechanism of Bimetallic Water Oxidation Catalysts

In this study, we highlight the impact of catalyst geometry on the formation of O-O bonds in Cu2 and Fe2 catalysts. A series of Cu2 complexes with diverse linkers are designed as electrocatalysts for water oxidation. Interestingly, the catalytic performance of these Cu2 complexes is enhanced as their molecular skeletons become more rigid, which contrasts with the behavior observed in our previous investigation with Fe2 analogs. Moreover, mechanistic studies reveal that the reactivity of the bridging O atom results in distinct pathways for O-O bond formation in Cu2 and Fe2 catalysts. In Cu2 systems, the coupling takes place between a terminal CuIII -OH and a bridging μ-O⋅ radical. Whereas in Fe2 systems, it involves the coupling of two terminal Fe-oxo entities. Furthermore, an in-depth structure-activity analysis uncovers the spatial geometric prerequisites for the coupling of the terminal OH with the bridging μ-O⋅ radical, ultimately leading to the O-O bond formation. Overall, this study emphasizes the critical role of precisely adjusting the spatial geometry of catalysts to align with the O-O bonding pathway.

Precise Tuning of Bilayer Ultrasmall MoS2 Featuring Inhibition of Carrier Recombination and Fast Surface Chemistry for Green H2 Evolution

Achieving water splitting to produce green H2 , using the noble-metal-free MoS2 , has attracted huge interest from researchers. However, tuning the number of MoS2 layers precisely while obtaining small lateral sizes to surge the H2 -evolution rate is a tremendous challenge. Here, a bottom-up strategy is designed for the in situ growth of ultrasmall lateral-sized MoS2 with tunable layers on CdS nanorods (CN) by controlling the decomposition temperature and concentration of substrate seed (NH4 )2 MoS4 . Here, the bilayer MoS2 and CN coupling (2L-MoS2 /CN) exhibits the optimum photocatalytic activity. Compared to thicker MoS2 , the 2L-MoS2 has sufficient reduction capacity to drive photocatalytic H2 evolution and the ultrasmall lateral size provides more active sites. Meanwhile, the indirect bandgap, in contrast to the direct bandgap of the monolayer MoS2 , suppresses the carrier recombination transferred to 2L-MoS2 . Under the synergistic effect of both, 2L-MoS2 /CN has fast surface chemical reactions, resulting in the photocatalytic H2 -evolution rate of up to 41.86 mmol g-1 h-1 . A novel strategy is provided here for tuning the MoS2 layers to achieve efficient H2 evolution.

Conjugated Molecules Based Multi-Component Artificial Photosynthesis System for Producing Multi-Objective Products

The development of artificial photosynthesis systems that mimics natural photosynthesis can help address the issue of energy scarcity by efficiently utilizing solar energy. Here, it presents liposomes-based artificial photosynthetic nanocapsules (PSNC) integrating photocatalytic, chemical catalytic, and biocatalytic systems through one-pot method. The PSNC contains 5,10,15,20-tetra(4-pyridyl) cobalt-porphyrin, tridipyridyl-ruthenium nitrate, oligo-pphenyl-ethylene-rhodium complex, and creatine kinase, efficiently generating oxygen, nicotinamide adenine dinucleotide (NADH), and adenosine triphosphate with remarkable enhancements of 231%, 30%, and 86%, compared with that of molecules mixing in aqueous solution. Additionally, the versatile PSNC enables simulation of light-independent reactions, achieving a controllable output of various target products. The regenerated NADH within PSNC further facilitates alcohol dehydrogenase, yielding methanol with a notable efficiency improvement of 37%. This work introduces a promising platform for sustainable solar energy conversion and the simultaneous synthesis of multiple valuable products in an ingenious and straightforward way.

Organic Semiconducting Polymers for Augmenting Biosynthesis and Bioconversion

Solar-driven biosynthesis and bioconversion are essential for achieving sustainable resources and renewable energy. These processes harness solar energy to produce biomass, chemicals, and fuels. While they offer promising avenues, some challenges and limitations should be investigated and addressed for their improvement and widespread adoption. These include the low utilization of light energy, the inadequate selectivity of products, and the limited utilization of inorganic carbon/nitrogen sources. Organic semiconducting polymers offer a promising solution to these challenges by collaborating with natural microorganisms and developing artificial photosynthetic biohybrid systems. In this Perspective, we highlight the latest advancements in the use of appropriate organic semiconducting polymers to construct artificial photosynthetic biohybrid systems. We focus on how these systems can enhance the natural photosynthetic efficiency of photosynthetic organisms, create artificial photosynthesis capability of nonphotosynthetic organisms, and customize the value-added chemicals of photosynthetic synthesis. By examining the structure-activity relationships and emphasizing the mechanism of electron transfer based on organic semiconducting polymers in artificial photosynthetic biohybrid systems, we aim to shed light on the potential of this novel strategy for artificial photosynthetic biohybrid systems. Notably, these coupling strategies between organic semiconducting polymers and organisms during artificial photosynthetic biohybrid systems will pave the way for a more sustainable future with solar fuels and chemicals.

Enabling Long-Life Aqueous Organic Redox Flow Batteries with a Highly Stable, Low Redox Potential Phenazine Anolyte

Aqueous organic redox flow batteries (AORFBs) are considered a promising energy storage technology due to the sustainability and designability of organic active molecules. Despite this, most of AORFBs suffer from limited stability and low voltage because of the chemical instability and high redox potential of organic molecules in anolyte. Herein, we propose a new phenazine derivative, 4,4'-(phenazine-2,3-diylbis(oxy))dibutyric acid (2,3-O-DBAP), as a water-soluble and chemically stable anodic active molecules. By combining calculations and experiments, we demonstrate that 2,3-O-DBAP exhibits a higher solubility, a lower redox potential (-0.699 V vs SHE), and greater chemical stability than other O-DBAP isomers. Then, we demonstrate a long-lasting flow cell with an average discharge voltage of 1.12 V, a low fade rate of 0.0127%, and a lifespan of 62 days at pH 14 using 2,3-O-DBAP paired with ferri/ferrocyanide. The negligible self-discharge behavior also verifies the high stability of 2,3-O-DBAP. These results highlight the importance of molecular engineering for AORFBs.

Efficient and stable visible-light-driven Z-scheme overall water splitting using an oxysulfide H2 evolution photocatalyst

So-called Z-scheme systems permit overall water splitting using narrow-bandgap photocatalysts. To boost the performance of such systems, it is necessary to enhance the intrinsic activities of the hydrogen evolution photocatalyst and oxygen evolution photocatalyst, promote electron transfer from the oxygen evolution photocatalyst to the hydrogen evolution photocatalyst, and suppress back reactions. The present work develop a high-performance oxysulfide photocatalyst, Sm2Ti2O5S2, as an hydrogen evolution photocatalyst for use in a Z-scheme overall water splitting system in combination with BiVO4 as the oxygen evolution photocatalyst and reduced graphene oxide as the solid-state electron mediator. After surface modifications of the photocatalysts to promote charge separation and redox reactions, this system is able to split water into hydrogen and oxygen for more than 100 hours with a solar-to-hydrogen energy conversion efficiency of 0.22%. In contrast to many existing photocatalytic systems, the water splitting activity of the present system is only minimally reduced by increasing the background pressure to 90 kPa. These results suggest characteristics suitable for applications under practical operating conditions.

Soluble Gd6Cu24 clusters: effective molecular electrocatalysts for water oxidation

The water oxidation half reaction in water splitting for hydrogen production is extremely rate-limiting. This study reports the synthesis of two heterometallic clusters (Gd6Cu24-IM and Gd6Cu24-AC) for application as efficient water oxidation catalysts. Interestingly, the maximum turnover frequency of Gd6Cu24-IM in an NaAc solution of a weak acid (pH 6) was 319 s-1. The trimetallic catalytic site, H2O-GdIIICuII2-H2O, underwent two consecutive two-electron two-proton coupled transfer processes to form high-valent GdIII-O-O-CuIII2 intermediates. Furthermore, the O-O bond was formed via intramolecular interactions between the CuIII and GdIII centers. The results of this study revealed that synergistic catalytic water oxidation between polymetallic sites can be an effective strategy for regulating O-O bond formation.

Oligo(phenylenevinylene)-Based Covalent Organic Frameworks with Kagome Lattice for Boosting Photocatalytic Hydrogen Evolution

Covalent organic frameworks (COFs) have shown great advantages as photocatalysts for hydrogen evolution. However, the effect of linkage geometry and type of linkage on the extent of π-electron conjugation in the plane of the framework and photocatalytic properties of COFs remains a significant challenge. Herein, two Kagome (kgm) topologic oligo(phenylenevinylene)-based COFs are designed and synthesized for boosting photocatalytic hydrogen evolution via a "two in one" strategy. Under visible light irradiation, COF-954 with 5 wt% Pt as cocatalyst exhibits high hydrogen evolution rate (HER) of 137.23 mmol g-1 h-1 , outperforming most reported COF-based photocatalysts. More importantly, even in natural seawater, COF-954 shows an average HER of 191.70 mmol g-1 h-1 under ultraviolet-visible (UV-vis) light irradiation. Additionally, the water-drainage experiments indoors and outdoors demonstrate that 25 and 8 mL hydrogen gas could be produced in 80 min under UV-vis light and natural sunlight, respectively, corresponding to a high HER of 167.41 and 53.57 mmol h-1 g-1 . This work not only demonstrates an effective design strategy toward highly efficient COF-based photocatalysts, but also shows the great potential of using the COF-based photocatalysts for photocatalytic hydrogen evolution.

Multiscale Synergetic Bandgap/Structure Engineering in Semiconductor Nanofibrous Aerogels for Enhanced Solar Evaporation

Solar-driven interface evaporation has been identified as a sustainable seawater desalination and water purification technology. Nonetheless, the evaporation performance is still restricted by salt deposition and heat loss owing to weak solar spectrum absorption, tortuous channels, and limited plane area of conventional photothermal material. Herein, the semiconductor nanofibrous aerogels with a narrow bandgap, vertically aligned channels, and a conical architecture are constructed by the multiscale synergetic engineering strategy, encompassing bandgap engineering at the atomic scale and structure engineering at the nano-micro scale. As a proof-of-concept demonstration, a Co-doped MoS2 nanofibrous aerogel is synthesized, which exhibits the entire solar absorption, superhydrophilic, and excellent thermal insulation, achieving a net evaporation rate of 1.62 kg m-2 h-1 under 1 sun irradiation, as well as a synergistically efficient dye ion adsorption function. This work opens up new possibilities for the development of solar evaporators for practical applications in clean water production.

Solar-powered simultaneous highly efficient seawater desalination and highly specific target extraction with smart DNA hydrogels

Obtaining freshwater and important minerals from seawater with solar power facilitates the sustainable development of human society. Hydrogels have demonstrated great solar-powered water evaporation potential, but highly efficient and specific target extraction remains to be expanded. Here, we report the simultaneous highly efficient seawater desalination and specific extraction of uranium with smart DNA hydrogels. The DNA hydrogel greatly promoted the evaporation of water, with the water evaporation rate reached a high level of 3.54 kilograms per square meter per hour (1 kilowatt per square meter). Simultaneously, uranyl-specific DNA hydrogel exhibited a high capture capacity of 5.7 milligrams per gram for uranium from natural seawater due to the rapid ion transport driven by the solar powered interfacial evaporation and the high selectivity (10.4 times over vanadium). With programmable functions and easy-to-use devices, the system is expected to play a role in future seawater treatment.

Lead in the Presence of Iron under Alkaline Conditions for the Oxygen-Evolution Reaction

The oxygen-evolution reaction (OER) is a bottleneck in water splitting, which is a critical process for energy storage. In this study, the electrochemistry of Pb in the absence or presence of K2FeO4, as a soluble Fe source, is examined at pH ≈ 13. Our findings indicate that Pb exhibits limited catalytic activity for the OER under alkaline conditions. However, upon the addition of K2FeO4 to the electrolyte, a significant enhancement in the OER activity is observed in the presence of Pb. A notable observation in this study is the formation of stable Fe(IV) species following the OER during chronoamperometry experiments conducted in an alkaline solution. In addition to in situ Raman and visible spectroscopies, the operated electrodes have been characterized by high-resolution transmission electron microscopy, scanning electron microscopy, electron spin resonance spectroscopy, X-ray diffraction, electrochemical methods, electron paramagnetic resonance, and X-ray absorption spectroscopy. Through our experimental investigations, it is consistently observed that the presence of Fe ions on the surface of Pb/PbOx serves as an effective catalyst for the OER. However, it is important to note that this heightened OER activity is only temporary due to the low adhesion of Fe ions on the surface of Pb/PbOx.

Scalable Ultralight Wood-Inspired Aerogel with Vertically Aligned Micrometer Channels for Highly Efficient Solar Interfacial Desalination

An ultralight material that simultaneously combines remarkably rapid water transportation, highly efficient photothermal conversion, and excellent thermal insulation is highly desired for solar-driven interfacial desalination but was challenging. In this work, inspired by the unique natural structure of wood, we developed an ultralight aerogel by ice-templated synthesis as an integrated interfacial evaporator for solar-driven water production. The interior features vertically aligned biomimetic microscale channels facilitating rapid transportation of water molecules, while an improved photothermal interface allows high solar absorption and conversion via nonradiative relaxation and molecular vibrations. The biomimetic aerogel is ultralight with a density as low as 0.06 g/cm3, especially its fabrication is size- and shape-programmable as a whole and easily scalable. Additionally, the outstanding thermal insulation of the aerogel focuses heat precisely at the evaporation interface, reducing ineffective heat loss, while the uniformly distributed large-sized channels promote the dynamic convection of high concentration salt ions on the evaporator surface. Consequently, the evaporator shows broadband light absorption of 92.7%, leading to a water evaporation rate reaching 4.55 kg m-2 h-1 under 3 simulated solar irradiations, much higher than that of other reported evaporators with randomly distributed pores. This work provides new insight into advanced hybrid aerogels for highly efficient and durable solar-driven interfacial desalination systems.

Water Activation in Solar-Powered Vapor Generation

Solar-powered vapor evaporation (SVG), based on the liquid-gas phase conversion concept using solar energy, has been given close attention as a promising technology to address the global water shortage. At molecular level, water molecules escaping from liquid water should overcome the attraction of the molecules on the liquid surface layer to evaporate. For this reason, it is better to reduce the energy required for evaporation by breaking a smaller number of hydrogen bonds or forming weak hydrogen bonds to ensure efficient and convenient vapor production. Many novel evaporator materials and effective water activation strategies have been proposed to stimulate rapid steam production and surpass the theoretical thermal limit. However, an in-depth understanding of the phase/enthalpy change process of water evaporation is unclear. In this review, a summary of theoretical analyses of vaporization enthalpy, general calculations, and characterization methods is provided. Various water activation mechanisms are also outlined to reduce evaporation enthalpy in evaporators. Moreover, unsolved issues associated with water activation are critically discussed to provide a direction for future research. Meanwhile, significant pioneering developments made in SVG are highlighted, hoping to provide a relatively entire chain for more scholars who are just stepping into this field.

Optimized polarization-independent Chand-Bali nano-antenna for thermal IR energy harvesting

A novel, polarization-independent, wide-angle reception Chand-Bali nano-antenna is proposed. An adjoint-based optimization algorithm is used to create the same resonance at both linear polarizations of the incident radiation. The nano-antenna optimal parameters reveal that two hot spots with a strong field enhancement are created. These hot-spots could be integrated with metal-insulator-metal (MIM) diodes to form a rectenna for infrared (IR) energy harvesting. The metallic resonators allow for selecting several materials to facilitate the fabrication of the nano-antenna and the MIM diode. The Chand-Bali-based IR rectennas are investigated and simulations demonstrate an improvement of more than one order of magnitude in efficiency compared to ones using traditional nano-antennas.

Flux-Assisted Synthesis of Y2 Ti2 O5 S2 for Photocatalytic Hydrogen and Oxygen Evolution Reactions

Photocatalytic water splitting is an ideal means of producing hydrogen in a sustainable manner, and developing highly efficient photocatalysts is a vital aspect of realizing this process. The photocatalyst Y2 Ti2 O5 S2 (YTOS) is capable of absorbing at wavelengths up to 650 nm and exhibits outstanding thermal and chemical durability compared with other oxysulfides. However, the photocatalytic performance of YTOS synthesized using the conventional solid-state reaction (SSR) process is limited owing to the large particle sizes and structural defects associated with this synthetic method. Herein, we report the synthesis of YTOS particles by a flux-assisted technique. The enhanced mass transfer efficiency in the flux significantly reduced the preparation time compared with the SSR method. In addition, the resulting YTOS showed improved photocatalytic H2 and O2 evolution activity when loaded with Rh and Co3 O4 co-catalysts, respectively. These improvements are attributed to the reduced particle size and enhanced crystallinity of the material as well as the slower decay of photogenerated carriers on a nanosecond to sub-microsecond time range. Further optimization of this flux-assisted method together with suitable surface modification is expected to produce high-quality YTOS crystals with superior photocatalytic activity.

Investigation of the Solar Hydrogen Sensitivity of GeSe Thin Film Photoelectrode with Photoelectrochemical Environment

GeSe photovoltaic thin films are very promising for photoelectrochemical (PEC) hydrogen evolution. The GeSe-based PEC water splitting device is a system containing a photoelectrode, electrolyte, and other packages, and the performance of the GeSe photoelectrode inside the system is very sensitive to the PEC system environment, such as the electrolyte temperature, pH, and concentration. Here, we reveal how the electrolyte environment at the electrolyte/photoelectrode interface influences the optoelectronic/PEC properties of GeSe photoelectrodes. It was found that the photocurrent density of the GeSe photoelectrode increased with temperature between 10 and 50 °C but decreased when the temperature was over 50 °C. In addition, the pH values of the electrolyte were inversely proportional to the photocurrent density of the GeSe photoelectrode. Moreover, the PEC performance improved as the sodium ion concentration of the electrolyte increased. The results in this work should provide a new direction for further optimizing the performance of photoelectrodes.

Rhodium-Doped Barium Titanate Perovskite as a Stable p-Type Photocathode in Solar Water Splitting

Solar water splitting from a p-n-conjugated photoelectrochemical (PEC) system is a promising way to produce hydrogen sustainably. At present, finding a compatible p-type photocathode material for the p-n system remains a great challenge in consideration of the photocurrent and stability. This paper highlighted a promising candidate, Rh/BaTiO3, by switching BaTiO3 from an n-type photoanode to a p-type photocathode upon Rh doping. The dopant activated visible light absorption up to 550 nm and an onset potential as high as 1.0 V (vs RHE). Using surface photovoltage spectroscopy as a powerful characterization tool, the n- to p-type transition of the semiconductor was studied and explained microscopically by which we quantitatively isolated the cathodic contribution caused by the Rh dopant. Unbiased overall solar water splitting was accomplished by serially connecting the Pt/Rh/BaTiO3 photocathode to a CoOx/Mo/BiVO4 photoanode, which produced a solar to hydrogen conversion efficiency of 0.1% and an excellent stability over 100 h of operation at ambient pressure. This work revealed the key role that the Rh dopant played in the n- to p-type adjustment of titanate semiconductors and demonstrated its great potential for application in PEC water splitting.

Effect of Interfacial SiOx Defects on the Functional Properties of Si-Transition Metal Oxide Photoanodes for Water Splitting

The transfer of photogenerated charges through interfaces in heterojunction photoanodes is a key process that controls the efficiency of solar water splitting. Considering Co3O4/SiOx/Si photoanodes prepared by physical vapor deposition as a representative case study, it is shown that defects normally present in the native SiOx layer dramatically affect the onset of the photocurrent. Electron paramagnetic resonance indicates that the signal of defects located in dangling bonds of trivalent Si atoms at the Si/SiOx interface vanishes upon vacuum annealing at 850 °C. Correspondingly, the photovoltage of the photoanode increases to ≈500 mV. Similar results are obtained for NiO/SiOx/Si photoanodes. Photoelectrochemical analysis and impedance spectroscopy (in solution and in the solid state) indicate how the defect annealing modifies the Co3O4/SiOx/Si junction. This work shows that defect annealing at the solid-solid interface in composite photoanodes strongly improves the efficiency of charge transfer through interfaces, which is the basis for effective solar-to-chemical energy conversion.

Making the connections: physical and electric interactions in biohybrid photosynthetic systems

Biohybrid photosynthesis systems, which combine biological and non-biological materials, have attracted recent interest in solar-to-chemical energy conversion. However, the solar efficiencies of such systems remain low, despite advances in both artificial photosynthesis and synthetic biology. Here we discuss the potential of conjugated organic materials as photosensitisers for biological hybrid systems compared to traditional inorganic semiconductors. Organic materials offer the ability to tune both photophysical properties and the specific physicochemical interactions between the photosensitiser and biological cells, thus improving stability and charge transfer. We highlight the state-of-the-art and opportunities for new approaches in designing new biohybrid systems. This perspective also summarises the current understanding of the underlying electron transport process and highlights the research areas that need to be pursued to underpin the development of hybrid photosynthesis systems.