Solar-to-hydrogen efficiency of more than 9% in photocatalytic water splitting

In situ construction of Mn3O4 cocatalyst on sodium poly(heptazine imides) for enhanced photocatalytic reduction of water and synergetic oxidation of amines

Photocatalytic hydrogen production utilizing solar energy provides a pivotal strategy for realizing a carbon-neutral society. Cocatalyst-modified semiconductor materials have emerged as promising candidates for photocatalytic applications due to their ability to facilitate the spatial separation and directional migration of photogenerated electron-hole pairs. Nevertheless, those systems often face challenges such as intricate preparation procedures and issues with non-compact recombination. Herein, we report a one-pot thermal treatment approach for synthesizing a composite of Mn3O4 nanoparticles and sodium poly(heptazine imides) (Na-PHI). Mn3O4 nanoparticles were in situ generated and embedded within the Na-PHI matrix during the sintering process. The resulted photocatalyst demonstrated significantly enhanced photoinduced charge separation efficiency, exhibiting approximately 6-fold and 3-fold improvements compared to pristine Mn3O4 and Na-PHI, respectively. The photocatalytic hydrogen evolution rate reached 14 μmol h-1, nearly 9 times that of Na-PHI (1.6 μmol h-1) in the aqueous solution of benzylamine (BA) under visible light illumination (780 nm ≥ λ ≥ 420 nm). Furthermore, the optimized Mn3O4-Na-PHI sample (Mn-Na-PHI) displayed a remarkably high photocatalytic hydrogen generation rate alongside the synchronous photo-oxidative coupling of aliphatic and aromatic amine under visible light. This work underscores the potential for rational design and synthesis of novel Na-PHI-based functional composites for sustainable energy applications.

Engineering bidirectional charge transport channels boosts solar driven sulfion oxidation upgrading coupled with hydrogen production

The inefficient charge separation and transport remains a bottleneck in photocatalysis. While various strategies have been explored to improve this process, most focus on single-sided modulation either the conduction-band electrons or valence-band holes, limiting overall improvement. Herein, an innovative coupling modification approach is adopted where Ru and α-Fe2O3 (FO) nanoparticles are integrated onto ZnIn2S4 (ZIS) to prepare Ru/ZnIn2S4/α-Fe2O3, and constructs dual charge transfer pathways for electrons and holes. This bidirectional channel configuration significantly enhances carrier separation and accumulation, enabling Ru as an electron (e-) mediator and FO as a hole (h+) extraction facilitator, driving simultaneous redox reactions, and enabling substantial improvement in the photocatalytic sulfur oxidation process coupled with hydrogen generation. This approach enhances interface charge separation/spatial accumulation and provides valuable guidance for designing and developing advanced high-efficiency photocatalytic systems.

A photothermal-photocatalytic layered aerogel for harvesting water and hydrogen from seawater

Photocatalytic hydrogen production from seawater holds potential to decrease the use of fresh or pre-treated water. However, direct photocatalytic splitting of seawater currently encounters challenges such as corrosion of catalyst and unsatisfied stability. To address these issues, we have integrated seawater desalination with photocatalytic water vapor splitting for in-situ hydrogen production, while also obtaining freshwater. This approach avoids direct contact between photocatalytic materials and seawater solution, effectively mitigating corrosion and enhancing hydrogen production performance. Based on this design, we constructed a layered structure of photothermal-photocatalytic aerogel material via in-situ synthesis method and designed corresponding device for freshwater-hydrogen coproduction, demonstrating notable hydrogen production rate of 17.94 mmol m-2 h-1 with solar-to-hydrogen efficiency of 0.12 ± 0.02 % and freshwater production rate of 0.92 kg m-2 h-1. This work demonstrates significant practical value in photothermal-photocatalysis field, potentially addressing the problem of energy and water scarcity in off-grid region.

Photo-thermal coupling-mediated enhancement in CO2 conversion: Key role of thermal effect and cobalt valence change-regulated electron-transfer orientation

Solar-driven CO2 conversion into fuels using particulate photocatalysts is a promising strategy for mitigating CO2 emissions with minimal environmental impact. However, the efficiency of CO2 photoreduction remains limited by the inherent trade-off between light absorption and charge transfer kinetics in single photocatalysts. Herein, we propose an innovative microtubular photocatalytic system consisting of integrated photothermal-photocatalytic materials. The system is based on hollow microtubular g-C3N4 substrates, which are wrapped with thin layers of graphene oxide (GO) acting as photothermal generators, while CoS2 nanoparticles are embedded between the layers to facilitate charge transfer. The synergistic effects of photon and thermal energy significantly reduce the activation energy by approximately 14 times, thereby promoting oriented electron transfer. Under full spectrum irradiation, the system exhibits superior CO2 reduction performance, achieving CO and CH4 yields of 143.73 and 60.27 μmol g-1, respectively, surpassing the combined contributions from light and heat alone.

Quantum Well Superlattice Heteronanostructures for Efficient Photocatalytic Hydrogen Evolution

In this study, we construct a quantum well effect-based two-dimensional Z-scheme superlattice heteronanostructure photocatalyst constructed from hydrogen-bonded porphyrin organic frameworks (HOFs) and carbon nitride. Porphyrin HOFs extend spectral absorption, while their π-conjugation and electron density variations significantly enhance charge separation and exhibit favorable alignment with the energy levels of carbon nitride, thereby enabling efficient charge transfer. Carboxylic acid channels in the HOFs further promote the decomposition of water molecules, thereby boosting hydrogen production. Experimental results indicate an improvement in carrier separation efficiency from 6.97 to 50.31%, resulting in a 935-fold increase in the hydrogen evolution rate of 187.2 mmol/g/h. Such a rate represents the highest performance among the currently reported porphyrin-based and carbon-based photocatalysts. This work highlights the potential of quantum well-based heterostructure design in optimizing photocarrier dynamics, providing a promising strategy for advancing photocatalytic hydrogen evolution.

A standalone bismuth vanadate-silicon artificial leaf achieving 8.4% efficiency for hydrogen production

The development of scalable photoelectrochemical water splitting with high solar-to-hydrogen efficiency and long-term stability is essential while challenging for practical application. Here, we design a BiVO4 photoanode with gradient distributed oxygen vacancies, which induces strong dipole fields to promote charge separation. Growing sea-urchin-like FeOOH cocatalyst on the photoanode leads to a photocurrent density of 7.0 mA cm-2 at 1.23 V versus the reversible hydrogen electrode and is stable for over 520 h under AM 1.5 G illumination. By integrating with a silicon photovoltaic cell, the standalone artificial leaf achieves a solar-to-hydrogen efficiency of 8.4%. The scale-up of these artificial leaves up to 441 cm2 in size can deliver a solar-to-hydrogen efficiency of 2.7% under natural sunlight. Life cycle assessment analysis shows that solar water splitting has little environmental footprint for hydrogen production. Our study demonstrates the possibility of designing metal oxide-based artificial leaves for scalable solar hydrogen production.

Porous Microreactor Chip for Photocatalytic Seawater Splitting over 300 Hours at Atmospheric Pressure

Photocatalytic seawater splitting is an attractive way for producing green hydrogen. Significant progresses have been made recently in catalytic efficiencies, but the activity of catalysts can only maintain stable for about 10 h. Here, we develop a vacancy-engineered Ag3PO4/CdS porous microreactor chip photocatalyst, operating in seawater with a performance stability exceeding 300 h. This is achieved by the establishment of both catalytic selectivity for impurity ions and tailored interactions between vacancies and sulfur species. Efficient transport of carriers with strong redox ability is ensured by forming a heterojunction within a space charge region, where the visualization of potential distribution confirms the key design concept of our chip. Moreover, the separation of oxidation and reduction reactions in space inhibits the reverse recombination, making the chip capable of working at atmospheric pressure. Consequently, in the presence of Pt co-catalysts, a high solar-to-hydrogen efficiency of 0.81% can be achieved in the whole durability test. When using a fully solar-driven 256 cm2 hydrogen production prototype, a H2 evolution rate of 68.01 mmol h-1 m-2 can be achieved under outdoor insolation. Our findings provide a novel approach to achieve high selectivity, and demonstrate an efficient and scalable prototype suitable for practical solar H2 production.

Enhanced photocatalytic performance in seawater of donor-acceptor type conjugated polymers through introduction of alkoxy groups in the side chain

Previous studies have demonstrated that the donor (D)-acceptor (A) structure enables conjugated polymers (CPs) to effectively inhibit charge recombination, reduce exciton binding energy to a minimum, and broaden the light absorption spectrum, ultimately enhancing photocatalytic activity. Besides, side chain engineering is an effective approach to enhance photocatalytic performance by regulating surface chemistry and energy band structure of CPs. Herein, three D-A type CPs, namely TPD-T, TPD-MOT and TPD-DOT, were designed and synthesized using thieno[3,4-c]pyrrole-4,6-dione (TPD) as A units and thiophene with different alkyl/alkoxy groups side chain (as 3-octylthiophene (T), 3-methoxythiophene (MOT) and 3,4-ethylenedioxythiophene (DOT)) as D units, via an atom- and step-economic CH/CH cross-coupling polycondensation. The photocatalytic hydrogen production performance of these polymers driven by visible light was systematically evaluated in pure water and natural seawater. The results show that the hydrogen evolution rates (HERs) of the as-synthesized CPs in pure water and natural seawater significantly increased by 5 and 7 times, respectively, when the number of alkoxy groups on the side chain of polymers increased from 0 to 2. In particular, HERs of three polymers in natural seawater are distinctly better than that in pure water. Further, the steady-state photoluminescence (PL), time-resolved fluorescence decay, and electrochemical impedance spectroscopy (EIS) studies combined with density functional theory (DFT) simulations were carried out to figure out the possible mechanism of the enhanced photocatalytic performance of CPs by side chain engineering. This work indicates that side chain engineering contributes significantly to determine the photocatalytic activity of D-A polymers-based photocatalysts, and could serve as guidelines for organic photocatalysts with highly efficient hydrogen evolution performance.

Constructing Z-scheme between graphite nitride carbon and supramolecular zinc porphyrin to promote photocatalytic H2 evolution

The separation and transport of charge carriers between heterojunction interfaces are key factors that constrain their photocatalytic activity. In current study, a new binary heterojunction (BCN-N-SA) composed of g-C3N4 nanosheet (BCN-N) and self-assembled supramolecular zinc porphyrin (SA-ZnTCPP) was successfully synthesized for photocatalytic hydrogen evolution (PHE) from water splitting. The optimal PHE rate of BCN-N-SA reaches 23.895 mmol g-1 h-1, which is 38.05, 6.93 and 6.75 times higher than that of unassembled ZnTCPP, SA-ZnTCPP and BCN-N, respectively. It is revealed that a Z-scheme mechanism between BCN-N and SA-ZnTCPP has been constructed in BCN-N-SA, which efficiently promotes the separation and transport of photogenerated charge carriers, thereby greatly improving the PHE efficiency. This work indicates that constructing the Z-scheme mechanism through band regulation is an effective method to improve the PHE efficiency.

Enhanced Charge Transportation in Type II WO3/ZnWO4 Nanoflakes for Boosting Saline Water-splitting Reaction

Photoelectrochemical (PEC) water-splitting is an energy-efficient and eco-friendly technique to produce green hydrogen (H2). Here, WO3 is synthesized for saline water-splitting reaction. Initially, the activity of WO3 is enhanced through morphology tuning. Nanoparticles (NPs), thick nanosheets (TSs), and nanoflakes (NFs) of WO3 are synthesized, and their PEC activity is determined. The NFs show a photocurrent density of 1.53 mA/cm2 at 1.2 V vs. Ag/AgCl, whereas TSs and NPs can generate 1.17 mA/cm2 and 1.07 mA/cm2 at 1.2 V vs. Ag/AgCl, respectively. The low charge transportation rate inhibits the PEC performance of these NFs in water-splitting reactions. To mitigate this problem, the type-II heterojunction is constructed with optimized deposition of ZnWO4 on WO3, which favors the migration of charge-carriers in opposite directions, facilitating the charge-carrier separation and eventually enhancing the PEC activity. The optimized heterojunction shows a photocurrent density 1.5 times greater than bare WO3 and 2.4 times enhanced carrier density, 2.16×1021 cm-3. The heterostructure's rapid OCP decay and higher charge injection efficiency indicate an improved charge transport capability, the primary driving force for enhanced PEC activity. The stability of WO3/ZnWO4 is studied for one hour.

Recent Progress in External-Field Enhanced Photo-Electrochemistry

The ever-growing demands for energy supply have put great stress on environment protections. Photo-electrochemistry (PEC) is a repaid developing technique which can directly transform solar energy into chemical compounds and have been regarded as a promising strategy to solve the energy and environmental problems. However, the biggest restriction is the fast recombination of photo-generated charge carriers which greatly limits the PEC efficiency. In recent years, introducing external-field into PEC system have been proved to be a powerful method to enhance the PEC performance and attracted more and more attentions. In this review, we summarized the remarkable progresses in external-field enhanced PEC reactions including mechanical stress field, thermal field, electrical field, magnetic field and muti-field coupling. The enhancing principles of different external-fields have also been systemically discussed. Furthermore, the challenges and outlook of the external-field enhanced PEC reactions are presented.

Optimizing photocatalysis via electron spin control

Solar-driven photocatalytic technology holds significant potential for addressing energy crisis and mitigating global warming, yet is limited by light absorption, charge separation, and surface reaction kinetics. The past several years has witnessed remarkable progress in optimizing photocatalysis via electron spin control. This approach enhances light absorption through energy band tuning, promotes charge separation by spin polarization, and improves surface reaction kinetics via strengthening surface interaction and increasing product selectivity. Nevertheless, the lack of a comprehensive and critical review on this topic is noteworthy. Herein, we provide a summary of the fundamentals of electron spin control and the techniques employed to scrutinize the electron spin state of active sites in photocatalysts. Subsequently, we highlight advanced strategies for manipulating electron spin, including doping design, defect engineering, magnetic field regulation, metal coordination modulation, chiral-induced spin selectivity, and combined strategies. Additionally, we review electron spin control-optimized photocatalytic processes, including photocatalytic water splitting, CO2 reduction, pollutant degradation, and N2 fixation, providing specific examples and detailed discussion on underlying mechanisms. Finally, we outline perspectives on further enhancing photocatalytic activity through electron spin manipulation. This review seeks to offer valuable insights to guide future research on electron spin control for improving photocatalytic applications.

Efficient Hole Extraction and *OH Alleviation by Pd Nanoparticles on GaN Nanowires in Seawater for Solar-Driven H2 and H2O2 Generation

Photocatalytic seawater splitting into hydrogen and hydrogen peroxide (2H2O→H2↑ + H2O2) offers an ultimate solution for simultaneously generating green fuel and value-added chemicals by the two most earth-abundant resources i.e., solar energy and natural seawater. In this study, Pd nanoparticles are integrated with one-dimensional gallium nitride nanowires (Pd NPs/GaN NWs) on a silicon wafer to produce H2 and H2O2 from seawater powered by sunlight. In situ spectroscopic characterizations combined with computational investigations reveal that in this nanohybrid, Pd NPs function as an efficient hole extractor and *OH alleviator during photocatalysis. Meanwhile, the chloride ions in seawater facilitate the H2O→ H2 + H2O2 conversion by improving the charge dynamics and lowering the energy barrier of the key *OH self-coupling step over Pd sites in the catalytic system. As a result, the photocatalyst delivers an appreciable hydrogen production rate of 2.5 mmol⋅cm-2⋅h-1 with a light-to-hydrogen (LTH) efficiency of 4.38 % in natural seawater under concentrated light irradiation of 3 W⋅cm-2 without sacrificial agents and external energies. Notably, the water oxidation reaction produces 300 μmol/L of valuable H2O2 over a duration of 2 hours under a light intensity of 3 W/cm2 using a 20 mL water sample, achieving a light-to-chemical efficiency of 0.53 %. The photocatalyst shows excellent stability for up to 60 hours with a considerable turnover number of 1.42×107 moles H2 per mole of Pd. The outdoor test further suggests the great potential for solar-driven seawater splitting into green fuels and chemicals.

Metal Doped Multicomponent Copper-Based Arrays for Formaldehyde Oxidation Assisted Dual Hydrogen Production System

Green hydrogen production technology is an effective strategy for solving energy problems and environmental issues. In this paper, we report a bipolar hydrogen production system: Au-CuxO/CF∥Ru-CuxO/CF, in which the cathode produces hydrogen through the hydrogen evolution reaction (HER) process and the anode produces hydrogen through a formaldehyde oxidation reaction (FOR). It is found that when Au-CuxO/CF is used in FOR, the C-H bond of formaldehyde will be broken at low potential to produce reactive hydrogen H*. H* is recombined through the Tafel step (H* + H* ⇌ H2) to produce H2. At the same time, the formaldehyde is oxidized to a high-value-added product HCOOH. We found that the formation of grain boundary-rich structures on the Au-CuxO surface jointly promotes the oxidation of formaldehyde at low potentials. In addition, we introduced Ru elements into CuxO to enhance the cathodic HER. The FOR-HER system of Au-CuxO/CF∥Ru-CuxO/CF was tested in a flow cell. It produced a current density of 500 mA cm-2 at a potential of only 0.38 V. This work provides system construction and catalyst design ideas for bipolar hydrogen production at low voltages.

Walnut shell-based biochar-assisted Fe sites anchored carbon-rich g-C3N4: Boosting photodegradation of 2-Mercaptobenzothiazole though synergistic enhancement of Fe sites and C substitution

To expand the utilization of discarded walnut shells and enhance the photocatalytic activity of graphitic carbon nitride(g-C3N4), the carbon-rich graphitic carbon nitride anchored with Fe sites (FeW-CN) was synthesized via a walnut shell-based biochar-assisted strategy. Unlike the direct thermal copolymerization of melamine for g-C3N4, the iron-loaded walnut shell-based biochar (FeW) was first synthesized, followed by thermal copolymerization of melamine with FeW to form FeW-CN. The C substitution on the triazine ring enhanced the light absorption and electron migration for FeW-CN. And the Fe sites interacting with N-(C)3 further improved the migration and the utilization rate of photogenerated carriers. During the degradation of 2-Mercaptobenzothiazole, FeW-CN showed excellent photocatalytic performance and stability compared with g-C3N4. Moreover, FeW-CN maintained excellent photocatalytic performance in river water. Combination of electron paramagnetic resonance with active species quenching experiments, the synergistic mechanism of singlet oxygen, holes, and superoxide radicals was confirmed in the FeW-CN system. Compared to g-C3N4, the Fe sites and C substitution enhanced the production of singlet oxygen.

A first-principles study of interfacial vacancies in the β-CsPbI3/1T-MoS2 heterostructure towards photocatalytic applications

Halide perovskite (HP) composites with transition metal dichalcogenides (TMDs) have attracted attention as promising photocatalysts for hydrogen production through solar-driven water splitting but their working mechanism is yet unclear. Here, we propose novel heterostructures composed of all-inorganic HP β-CsPbI3 and metallic TMD 1T-MoS2 and investigate the influence of interfacial vacancies on their interfacial properties using first-principles calculations. Using CsPbI3(001)/MoS2(001) interface slab models with a minimal lattice mismatch, we calculate the interface formation and interlayer binding energies, finding that the PbI2-terminated interfaces have better stability and stronger binding strength than the CsI-terminated ones and iodine vacancy enhances the binding properties. Our calculations demonstrate that photo-generated electrons are transferred from CsPbI3 to MoS2, inducing a dipole moment at the interface that prevents recombination of electrons and holes, and this desirable process for the hydrogen evolution reaction (HER) is enhanced by forming an I vacancy. Through analysis of the electronic density of states, we reveal that the I vacancy reduces the band gap of CsPbI3 by down-shifting its conduction band minimum level and forming a shallow defect state, being favourable for enhancing the HER performance on the MoS2 surface. This work highlights a way to design advanced photocatalysts based on HP/TMD composites for hydrogen production using solar energy.

Decoupling H2 and O2 Release in Particulate Photocatalytic Overall Water Splitting Using a Reversible O2 Binder

H2 and O2 evolutions occur simultaneously for conventional particulate photocatalytic overall water splitting (PPOWS), leading to a significant backward reaction and the formation of an explosive H2/O2 gas mixture. This is an issue that must be addressed prior to industrialization of PPOWS. Here, a convenient, cost-effective, and scalable concept is introduced to uncouple hydrogen and oxygen production for PPOWS. Based on this idea, a three-component photocatalyst, Co(5 %)-HPCN/(rGO/Pt), is constructed, consisting of a photoresponsive chip (HPCN), a H2 evolution cocatalyst (rGO/Pt), and a cobalt complex capable of reversibly binding O2 (Co), to achieve the decoupling of PPOWS under alternating UV and visible light irradiations. The asynchronous O2 and H2 evolution strategy have considerable flexibility regarding the photocatalyst structure and light sources suitable for PPOWS.

Controllable surface carrier type of metal oxide nanocrystals for multifunctional photocatalysis

Selectively harnessing photo-induced carriers to control surface photo-redox reactions can enable currently limited specificity in photocatalytic applications. By using a new approach to switching between dominant electron and hole charge transfer on the surfaces of metal oxide nanocrystals, depending on the optimal carrier for specific application functionality in photocatalytic pollutant degradation, H2 production, CO2 reduction, and gas sensing. The approach is based on the surface redox properties of custom-designed p-n hetero-structured hybrid nanoparticles (NPs) containing copper oxide, and wide-gap metal oxide semiconductors (MOSs). The customized CuxO/ZnO (CXZ) heterostructures ensure effective charge separation and surface reactions driven by UV-vis excited highly reactive holes and show high performance in the photo-oxidative degradation of organic dyes and NO2 gas sensing. By switching the dominant surface carrier type from holes to electrons, the hybrids exhibit excellent performance in photocatalytic H2 evolution and CO2 reduction. This work offers a generic approach to engineering multipurpose photocatalytic materials.

Anti-Kasha's rule for semiconductor photocatalytic reactions: the wavelength dependence of quantum efficiency

We reported the wavelength-dependent quantum efficiency phenomenon for the PCET reactions between alcohol and tBu3ArO˙ photocatalyzed by CdS or In2O3 for the first time. The excess energy beyond the lowest excited state energy level from incident photons can be introduced into the heterogeneous reaction, resulting in a significant impact on the kinetic rate.

Dual Regulation of Sensitizers and Cluster Catalysts in Metal-Organic Frameworks to Boost H2 Evolution

Photocatalytic efficiency is closely correlated to visible-light absorption ability, electron transfer efficiency and catalytic center activity of photocatalysts, nevertheless, the concurrent management of these factors to improve photocatalytic efficiency remains underexplored. Herein, we proposed a sensitizer/catalyst dual regulation strategy on the polyoxometalate@Metal-Organic Framework (POM@MOF) molecular platform to construct highly efficient photocatalysts. Impressively, Ni-Sb9@UiO-Ir-C6, obtained by coupling strong sensitizing [Ir(coumarin 6)2(bpy)]+ with Ni-Sb9 POM with extremely exposed nickel site [NiO3(H2O)3], can drive H2 evolution with a turnover number of 326923, representing a record value among all the POM@MOF composite photocatalysts. This performance is over 34 times higher than that of the typical Ni4P2@UiO-Ir constructed from [Ir(ppy)2(bpy)]+ and Ni4P2 POM. Systematical investigations revealed that dual regulation of sensitizing and catalytic centers endowed Ni-Sb9@UiO-Ir-C6 with strong visible-light absorption, efficient inter-component electron transfer and high catalytic activity to concurrently promote H2 evolution. This work opens up a new avenue to develop highly active POM@MOF photocatalysts by dual regulation of sensitizing/catalytic centers at the molecular level.

An integrated photocatalytic redox architecture for simultaneous overall conversion of CO2 and H2O toward CH4 and H2O2

Solar-driven overall conversion of CO2 and H2O into fuels and chemicals shows an ultimate strategy for carbon neutrality yet remains a huge challenge. Herein, an integrated photocatalytic redox architecture of Zn NPs/GaN Nanowires (NWs)/Si is explored for light-driven overall conversion of CO2 and H2O into CH4 and H2O2 simultaneously without any external sacrificial agents and additives. The as-designed architecture affords a benchmark CH4 activity of 189 mmol gcat-1 h-1 with a high selectivity of 93.6%, in the synchronized formation of H2O2 at a considerable rate of 25 m g-1 h-1. Moreover, a considerable turnover number of 27,280 mol CH4 per mol Zn was achieved over a long-term operation of 80 h. By operando spectroscopic characterizations, isotope experiments, and density functional theory calculations, it is unraveled that Zn sites are synergetic with GaN to drive CO2-to-CH4 conversion with a lowered energy barrier of 0.27 eV while inhibiting hydrogen evolution reaction with a relatively high energy barrier of 0.93 eV. Notably, owing to the unique surface properties of GaN, water is split into *OH and *H, followed by the formation of H2O2 because of the alleviated adsorption strength of *OH by Zn NPs. Together, the hierarchical architecture enables the achievement of high activity and high selectivity of CH4 from CO2 reduction in distilled water along with the generation of H2O2. This work provides an integrated photocatalytic redox architecture for the synchronized production of CH4 and H2O2 with the only inputs of CO2, distilled water, and light.

Spectroscopic Kinetic Insights into the Critical Role of Metal-Oxide Interfaces in Enhancing the Concentration of Surface-Reaching Photoexcited Charges

Surface modification of semiconductors with noble metals has been shown to effectively tune their photocatalytic activity. However, the photoinduced charge transfer processes at the metal/semiconductor interface and their impact on the concentration of surface-reaching photoexcited charges remain subjects of ongoing debate. In this study, we used time-resolved spectroscopy and kinetic analysis to investigate the behavior of surface-reaching photoholes in metal-loaded TiO2 nanoparticles. Our results reveal that the concentration of surface-reaching photoholes (Ch+(surf)) is highly dependent upon the type of metal and the resulting metal-oxide interface. Among the noble metals studied (Pt, Au, and Ag), Pt loading led to the most significant increase in Ch+(surf), with a nearly 3-fold enhancement compared to pristine TiO2. This enhancement was attributed to the generation of more abundant Ti3+ defects at the metal-oxide interface, which serve as hole trap states, thereby accelerating interfacial charge transfer, improving charge separation, and enriching Ch+(surf). These findings underscore the critical role of the metal-oxide interface in enhancing surface-reaching photoexcited charges, offering valuable insights for the design of advanced materials for solar energy conversion.

HydE Catalytic Mechanism Is Powered by a Radical Relay with Redox-Active Fe(I)-Containing Intermediates

[FeFe]-hydrogenases are enzymes that catalyze the redox interconversion of H+ and H2 using a six-iron active site, known as the H-cluster, which consists of a structurally unique [2Fe]H subcluster linked to a [4Fe-4S]H subcluster. A set of enzymes, HydG, HydE, and HydF, are responsible for the biosynthesis of the [2Fe]H subcluster. Among them, it is well established that HydG cleaves tyrosine into CO and CN- and forms a mononuclear [Fe(II)(Cys)(CO)2(CN)] complex. Recent work using EPR spectroscopy and X-ray crystallography show that HydE uses this organometallic Fe complex as its native substrate. The low spin Fe(II) center is reduced into an adenosylated Fe(I) species, which is proposed to form an Fe(I)Fe(I) dimer within HydE. The highly unusual transformation catalyzed by HydE draws interest in both biochemistry and organometallic chemistry. Due to the instability of the substrate, the intermediates, and the proposed product, experimental characterization of the detailed HydE mechanism and its final product is challenging. Herein, the catalytic mechanism of HydE is studied using hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations. A radical relay mechanism was found for the cleavage of the cysteine S-Cβ bond that is energetically favored with respect to a closed-shell mechanism involving unconventional proton transfer. In addition, we propose a pathway for the dimerization of two Fe(I) complexes within the HydE hydrophobic cavity, which is consistent with the recent experimental result that HydF can perform [FeFe]-hydrogenase maturation with a synthetic dimer complex as the substrate. These simulation results take us further down the path to a more complete understanding of these enzymes that synthesize one of Nature's most efficient energy conversion catalysts.

Template-free synthesis of single-crystal SrTiO3 nanocages for photocatalytic overall water splitting

In this study, we present a novel approach to achieve the template-free fabrication of nanocage-shaped SrTiO3 (N-STO) single crystals via molten salt flux treatment. Systematic characterizations demonstrate the high crystallinity and low defect density of N-STO. The N-STO single crystals enable overall water splitting (OWS) with hydrogen and oxygen evolution rates of 100.86 μmol h-1 g-1 and 44.2 μmol h-1 g-1, respectively, which is 5.7-fold higher than the porous SrTiO3 (P-STO) control.

Precisely Tuning Band Gaps of Hexabenzocoronene-Based MOFs Toward Enhanced Photocatalysis

Precise adjusting the band gaps in metal-organic frameworks (MOFs) is crucial for improving their visible-light absorption capacity during photocatalysis, presenting both a formidable challenge and a charming opportunity. This present study employed a symmetry-reduction strategy to pre-design six novel 4-connected ligands with systematic substituents (-NO2, -H, -tBu, -OCH3, -OH and -NH2) and synthesized the corresponding pillared-layer Zr-MOFs (NKM-668) retaining the hexaphenylbenzene fragment. Subsequently, the NKM-668 MOFs were transformed into large-π-conjugated hexabenzocoronene-based MOFs (pNKM-668) via the Scholl reaction. These twelve MOFs exhibited broad and tunable band gaps over 1.41 eV (ranging from 3.25 eV to 1.84 eV), and the photocatalytic CO2 conversion rate raised by 33.2-fold. This study not only enriches the type of hexaphenylbenzene-based MOFs, but also paves the way for nanographene-containing MOFs in the further application of photocatalysis.

Construction of Full-Spectrum-Response Bi3O4Br:Er3+@Bi2O3- x S-Scheme Heterojunction With [Bi─O] Tetrahedral Sharing by Integrated Upconversion and Photothermal Effect Toward Optimized Photocatalytic Performance

Designing and optimizing photocatalysts to maximize the use of sunlight and achieve fast charge transport remains a goal of photocatalysis technology. Herein, a full-spectrum-response Bi3O4Br:Er3+@Bi2O3- x core-shell S-scheme heterojunction is designed with [Bi─O] tetrahedral sharing using upconversion (UC) functionality, photothermal effects, and interfacial engineering. The UC function of Er3+ and plasmon resonance effect of Bi2O3- x greatly improves the utilization of sunlight. The equivalent layer structure of Bi3O4Br and Bi2O3- x facilitates the construction of high-quality S-scheme heterojunction interfaces with close atomic-level contact obtained from the [Bi─O] tetrahedral sharing and the resulting Bi3O4Br:Er3+@Bi2O3- x core-shell morphology, enabled efficient charge transfer. Furthermore, localized temperature increase, induced by photothermal effects, enhanced the chemical reaction kinetics. Benefiting from the distinctive construction, the Bi3O4Br:Er3+@Bi2O3- x heterojunctions exhibit excellent performance in the photocatalytic degradation of bisphenol A that is 2.40 times and 4.98 times greater than that of Bi3O4Br:Er3+ alone under full-spectrum light irradiation and near-infrared light irradiation, respectively. This work offers an innovative perspective for the design and fabrication of full-spectrum-response S-scheme heterojunction photocatalysts with efficient solar energy utilization based on high quality interfaces, UC functionality, and the photothermal effect.

Direct Partial Transformation of 2D Antimony Oxybromide to Halide Perovskite Heterostructure for Efficient CO2 Photoreduction

The photocatalytic activity of lead-free perovskite heterostructures currently suffers from low efficiency due to the lack of active sites and the inadequate photogenerated carrier separation, the latter of which is hindered by slow charge transfer at the heterostructure interfaces. Herein, a facile strategy is reported for the construction of lead-free halide-perovskite-based heterostructure with swift interfacial charge transfer, achieved through direct partial conversion of 2D antimony oxybromide Sb4O5Br2 to generate Cs3Sb2Br9/Sb4O5Br2 heterostructure. Compared to the traditional electrostatic self-assembly method, this approach endows the Cs3Sb2Br9/Sb4O5Br2 heterostructure with a tightly interconnected interface through in situ partial conversion, significantly accelerating interfacial charge transfer and thereby enhancing the separation efficiency of photogenerated carriers. The cobalt-doped Cs3Sb2Br9/Sb4O5Br2 heterostructure demonstrates a record-high electron consumption rate of 840 µmol g-1 h-1 for photocatalytic CO2 reduction to CO coupled with H2O oxidation to O2, which is over 74- and 16-fold higher than that of individual Sb4O5Br2 and Cs3Sb2Br9, respectively. This work provides an effective strategy for promoting charge separation in photocatalysts to improve the performance of artificial photosynthesis.

Synchronous Regulation of Ferroelectric and Spin Polarization for High-Efficiency Photocatalytic Water Splitting

Enhancing the ferroelectric polarization field and tuning the electron spin polarization as novel approaches to improve photocatalytic performance have sparked considerable research interest. Obviously, a straightforward strategy to simultaneously regulate ferroelectric and spin polarization will have a very attractive application prospect. In this study, a series of Bi4NbO8Cl-Ni photocatalysts are synthesized by doping different concentrations of magnetic element Ni into ferroelectric semiconductor Bi4NbO8Cl. Due to the significant difference in atomic radius, Ni doping induces greater structural distortion and enhances the deviation of positive and negative charge centers in the crystal, thereby resulting in a stronger ferroelectric polarization field. Moreover, spin polarization is induced in the electrons, and photogenerated carriers exhibit higher spatial separation efficiency under magnetic field. Thanks to the synchronous regulation of ferroelectric and spin polarization by Ni doping, the average rates of H2 and O2 production from photocatalytic water splitting over Bi4NbO8Cl-Ni under visible light are 342.6 and 207.1 µmol g-1 h-1, respectively, which are 10.6 and 2.7 times those of pure Bi4NbO8Cl. Notably, under an applied magnetic field of 300 mT, the average production rates are further promoted up to 616.7 and 331.4 µmol g-1 h-1. This study offers a novel strategy to significantly improve photocatalytic performance.

Surface-hydrogenated CrMnOx coupled with GaN nanowires for light-driven bioethanol dehydration to ethylene

Light-driven bioethanol dehydration offers attractive outlooks for the sustainable production of ethylene. Herein, a surface-hydrogenated CrMnOx is coupled with GaN nanowires (GaN@CMO-H) for light-driven ethanol dehydration to ethylene. Through combined experimental and computational investigations, a surface hydrogen-replenishment mechanism is proposed to disclose the ethanol dehydration pathway over GaN@CMO-H. Moreover, the surface-hydrogenated GaN@CMO-H can significantly lower the reaction energy barrier of the C2H5OH-to-C2H4 conversion by switching the rate-determining reaction step compared to both GaN and GaN@CMO. Consequently, the surface-hydrogenated GaN@CMO-H illustrates a considerable ethylene production activity of 1.78 mol·gcat-1·h-1 with a high turnover number of 94,769 mole ethylene per mole CrMnOx. This work illustrates a new route for sustainable ethylene production with the only use of bioethanol and sunlight beyond fossil fuels.

A scalable solar-driven photocatalytic system for separated H2 and O2 production from water

Solar-driven photocatalytic water splitting offers a sustainable pathway to produce green hydrogen, yet its practical application encounters several challenges including inefficient photocatalysts, sluggish water oxidation, severe reverse reactions and the necessity of separating produced hydrogen and oxygen gases. Herein, we design and develop a photocatalytic system composed of two separate reaction parts: a hydrogen evolution cell containing halide perovskite photocatalysts (MoSe2-loaded CH(NH2)2PbBr3-xIx) and an oxygen evolution cell containing NiFe-layered double hydroxide modified BiVO4 photocatalysts. These components are bridged by a I3-/I- redox couple to facilitate electron transfer, realizing efficient overall water splitting with a solar-to-hydrogen conversion efficiency of 2.47 ± 0.03%. Additionally, an outdoor scaled-up setup of 692.5 cm2 achieves an average solar-to-hydrogen conversion efficiency of 1.21% during a week-long test under natural sunlight. By addressing major limitations inherent in conventional photocatalytic systems, such as the cooccurrence of hydrogen and oxygen in a single cell and the resultant severe reverse reactions from hydrogen and oxygen recombination, this work introduces an alternative concept for photocatalytic system design, which enhances both efficiency and practicality.

Concentrated Solar-Driven Catalytic CO2 Reduction: From Fundamental Research to Practical Applications

Concentrated solar-driven CO2 reduction is a breakthrough approach to combat climate crisis. Harnessing the in-situ coupling of high photon flux density and high thermal energy flow initiates multiple energy conversion pathways, such as photothermal, photoelectric, and thermoelectric processes, thereby enhancing the efficient activation of CO2. This review systematically presents the fundamental principles of concentrated solar systems, the design and classification of solar-concentrating devices, and industrial application case studies. Meanwhile, key technological advances-from theoretical foundations to practical applications-are also discussed. At the microscopic level, a comprehensive analysis of multiscale reaction kinetics within the domain of photothermal synergistic catalysis has been conducted. This analysis elucidates the significance of catalyst design, further detailing the intricate regulatory mechanisms governing reaction pathways and active sites through nanostructured catalysts, single-atom catalysts, and metal-support interactions. However, the transition from laboratory research to industrial-scale application still faces challenges, including the complexity of system integration, energy density optimization, and economic feasibility. This review provides a theoretical framework and practical guidance through a complete investigation of current technological bottlenecks and future development directions, with the aim of driving key advances in concentrated solar-driven CO2 reduction catalysis.

Scandium-III-nitrides: A New Material Platform for Semiconductor Photocatalysts with High Reducing Power

Semiconductor nanowires have become emerging photocatalysts in artificial photosynthesis processes for solar fuel production. For reduction reactions, semiconductor photocatalysts with high reducing powers are highly desirable, especially for chemicals that are extremely difficult to reduce. This study introduces a new semiconductor photocatalyst, scandium (Sc)-III-nitrides, which have higher reducing powers than all conventional semiconductor photocatalysts. In specific, we focus on ScxGa1-xN (ScGaN) nanowires. The detailed material synthesis and characterization of such nanowires are explored, and the photocatalytic reduction of carbon dioxide (CO2), as an example of chemicals that are difficult to reduce, is also performed. The photocatalytic CO2 reduction using GaN, a well-known high-performance semiconductor photocatalyst, is conducted as well as a reference. It is found that compared to using GaN nanowires, using ScGaN nanowires can significantly increase the production rate of formic acid (HCOOH). Moreover, ScGaN nanowires can further reduce HCOOH to methanol (CH3OH).

Insight into the unique role of silver single-atom in atomic-thickness ZnIn2S4/g-C3N4 Van der Waals heterojunction for photocatalytic hydrogen evolution

The construction of ultra-close 2D atomic-thickness Van der Waals heterojunctions with high-speed charge transfer still faces challenges. Here, we synthesized single-layer ZnIn2S4 and g-C3N4, and introduced silver single atoms to regulate Van der Waals heterojunctions at the atomic level to optimize charge transfer and catalytic activity. At the atomic scale, the impact of detailed structural differences between the two characteristic surfaces of ZnIn2S4 ([Zn-S4] and [In-S4]) on catalytic performance has been first proposed. Experiments combined with the DFT study demonstrate that single atom Ag not only acts as a charge transfer bridge but also regulates the energy band and intrinsic catalytic activity. Benefiting from the enhanced electron delocalization, the synthesized catalyst ZIS/Ag@CN exhibits excellent photocatalytic performance, with a hydrogen production rate of 5.50 mmol·g-1·h-1, which is much higher than the reported Ag-based single-atom catalysts so far. This work provides a new understanding of atomic-level heterojunction interface regulation and modification.

Creating Spin Channels in SrCoO3 through Trigonal-to-Cubic Structural Transformation for Enhanced Oxygen Evolution/Reduction Reactions

Oxygen evolution and reduction reactions (OER and ORR) play crucial roles in energy conversion processes such as water splitting and air batteries, where spin dynamics inherently influence their efficiency. However, the specific contribution of spin has yet to be fully understood. In this study, we intentionally introduce a spin channel through the transformation of trigonal antiferromagnetic SrCoO2.5 into cubic ferromagnetic SrCoO3, aiming to deepen our understanding of spin dynamics in catalytic reactions. Based on the results from spherical-aberration-corrected microscopy, synchrotron absorption spectra, magnetic characterizations, and density functional theory calculations, it is revealed that surface electron transfer is predominantly governed by local geometric structures, while the presence of the spin channel significantly enhances the bulk transport of spin-polarized electrons, particularly under high current densities where surface electron transfer is no longer the limiting factor. The overpotential for OER is reduced by at least 70 mV at 150 mA cm-2 due to the enhanced conductivity from spin-polarized electrons facilitated by spin channels, with an expectation of even more significant reductions at higher current densities. This work provides a clearer picture of the role of spin in oxygen-involved electrocatalysis, providing critical insights for the design of more efficient catalytic systems in practical applications.

Integrated Carbon Layer and CoNiP Cocatalyst on SnWO4 Film for Enhanced Photoelectrochemical Water Splitting

α-SnWO4 is a promising semiconductor for solar water splitting, however, its performance is limited by weak water oxidation and poor charge transfer. In this study, we employ a vapor deposition method to uniformly implement a carbon layer onto the surface of SnWO4 coupled with a CoNiP cocatalyst, successfully constructing the integrated CoNiP/C/SnWO4 film photoanode and alleviating the oxidation of Sn2+ when loading electrocatalyst. Incorporating the carbon layer enhances the interface charge conduction behavior between the SnWO4 substrate and the CoNiP cocatalyst, thereby mitigating charge recombination. The synergistic interplay between the carbon layer and CoNiP leads to a remarkable achievement, as evidenced by the photocurrent of 1.72 mA cm-2 (1.23 V vs. RHE) observed for SnWO4 film measured in 0.2 M potassium phosphate buffer solution. In this work, we demonstrate the viability of tailoring SnWO4 photoanode and provide valuable insights for prospective advancements in modifying SnWO4 photoanode.

Recent advances in irradiation-mediated synthesis and tailoring of inorganic nanomaterials for photo-/electrocatalysis

Photo-/electrocatalysis serves as a cornerstone in addressing global energy shortages and environmental pollution, where the development of efficient and stable catalysts is essential yet challenging. Despite extensive efforts, it's still a formidable task to develop catalysts with excellent catalytic behaviours, stability, and low cost. Because of its high precision, favorable controllability and repeatability, radiation technology has emerged as a potent and versatile strategy for the synthesis and modification of nanomaterials. Through meticulous control of irradiation parameters, including energy, fluence and ion species, various inorganic photo-/electrocatalysts can be effectively synthesized with tailored properties. It also enables the efficient adjustment of physicochemical characteristics, such as heteroatom-doping, defect generation, heterostructure construction, micro/nanostructure control, and so on, all of which are beneficial for lowering reaction energy barriers and enhancing energy conversion efficiency. This review comprehensively outlines the principles governing radiation effects on inorganic catalysts, followed by an in-depth discussion of recent advancements in irradiation-enhanced catalysts for various photo-/electrocatalytic applications, such as hydrogen and oxygen evolution reactions, oxygen reduction reactions, and photocatalytic applications. Furthermore, the challenges associated with ionizing and non-ionizing radiation are discussed and potential avenues for future development are outlined. By summarizing and articulating these innovative strategies, we aim to inspire further development of sustainable energy and environmental solutions to drive a greener future.

Floating Photothermal Hydrogen Production

Solar-to-hydrogen (STH) is emerging as a promising approach for energy storage and conversion to contribute to carbon neutrality. The lack of efficient catalysts and sustainable reaction systems is stimulating the fast development of photothermal hydrogen production based on floating carriers to achieve unprecedented STH efficiency. This technology involves three major components: floating carriers with hierarchically porous structures, photothermal materials for solar-to-heat conversion and photocatalysts for hydrogen production. Under solar irradiation, the floating photothermal system realizes steam generation which quickly diffuses to the active site for sustainable hydrogen generation with the assistance of a hierarchically porous structure. Additionally, this technology is endowed with advantages in the high utilization of solar energy and catalyst retention, making it suitable for various scenarios, including domestic water supply, wastewater treatment, and desalination. A comprehensive overview of the photothermal hydrogen production system is present due to the economic feasibility for industrial application. The in-depth mechanism of a floating photothermal system, including the solar-to-heat effect, steam diffusion, and triple-phase interaction are highlighted by elucidating the logical relationship among buoyant carriers, photothermal materials, and catalysts for hydrogen production. Finally, the challenges and new opportunities facing current photothermal catalytic hydrogen production systems are analyzed.

Binary Iron-Manganese Cocatalyst for Simultaneous Activation of C-C and C-O Bonds to Maximally Utilize Lignin for Syngas Generation over InGaN

Solar-powered lignin reforming offers a carbon-neutral route for syngas production. This study explores a dual non-precious iron-manganese cocatalyst to simultaneously activate both C-C and C-O bonds for maximizing the utilization of various substituents of native lignin to yield syngas. The cocatalyst, integrated with InGaN nanowires on a Si wafer, affords a measurable syngas evolution rate of 42.4 mol gcat -1 h-1 from native lignin in distilled water with a high selectivity of 93 % and tunable H2/CO ratios under concentrated light, leading to a considerable light-to-fuel efficiency of 11.8 %. The high FeMn atom efficiency arising from the 1-dimensional nanostructure of InGaN enables the achievement of a high turnover frequency (TOF) of 220896 mol syngas per mol FeMn per hour. Combined experimental and theoretical investigations reveal that the synergetic iron-manganese cocatalyst supported by InGaN nanowires enables simultaneous activation of C-C and C-O bonds with comparable minimized dissociation energies, thus promising to maximally utilize different substituents of -OCH3, and -CH2CH2CH3 in lignin for syngas production. Moreover, the dual Fe-Mn cocatalyst demonstrates a most energetically favorable route for the consecutive release of hydrogen from •CH3 and •OH by the oxidative holes while inhibiting the reversion of hydrogen and hydroxyl into water.

Multi-Scale Hierarchical Organic Photocatalytic Platform for Self-Suspending Sacrificial Hydrogen Production from Seawater

The widespread application of photocatalysis for converting solar energy and seawater into hydrogen is generally hindered by limited catalyst activity and the lack of sustainable large-scale platforms. Here, a multi-scale hierarchical organic photocatalytic platform was developed, combining a photosensitive molecular heterojunction with a molecular-scale gradient energy level alignment and micro-nanoscale hierarchical pore structures. The ternary system facilitates efficient charge transfer and enhances photocatalytic activity compared to conventional donor-acceptor pairs. Meanwhile, the super-wetted hierarchical interfaces of the platform endow it with the ability to repeatedly capture light and self-suspend below the water surface, which simultaneously improves the light utilization efficiency, and reduces the adverse effects of salt deposition. Under a Xe lamp illumination, the hydrogen evolution rate of this organic platform utilizing a sacrificial agent can reach 165.8 mmol h-1 m-2, exceeding that of mostly inorganic systems as reported. And upon constructing a scalable system, the platform produced 80.6 ml m-2 of hydrogen from seawater within five hours at noon. More importantly, the outcomes suggest an innovative multi-scale approach that bridges disciplines, advancing the frontier of sustainable seawater hydrogen production driven by solar energy.

Suppressing Se Vacancies in Sb2Se3 Photocathode by In Situ Annealing with Moderate Se Vapor Pressure for Efficient Photoelectrochemical Water Splitting

Sb2Se3 emerges as a promising material for solar energy conversion devices. Unfortunately, the common deep-level defect VSe (selenium vacancy) in Sb2Se3 results in a low solar conversion efficiency. The post selenization process has been widely adopted for suppressing VSe. However, the effect of selenization on suppressing VSe is often compromised and even more VSe are induced due to defect-correlation. Herein, high-quality Sb2Se3 films are prepared using an unconventional selenization process, with precisely regulating in situ annealing Se vapor pressure. It is found that moderate Se vapor pressure annealing can efficiently suppress VSe by overcoming defect-correlation, as well as promotes grain growth and forms a better heterojunction band alignment. Consequently, the Sb2Se3 photocathode shows a high-level photocurrent of 19.5 mA cm-2 at 0 VRHE, an onset potential of 0.40 VRHE and a half-cell solar-to-hydrogen conversion efficiency of 1.9%, owing to the inhibited charge recombination, excellent charge transport and interface charge extraction. This work provides a significant insight to suppress deep-level defect VSe by adjusting Se vapor pressure for efficient Sb2Se3 photocathode.

Balancing the Charge Separation and Surface Reaction Dynamics in Twin-Interface Photocatalysts for Solar-to-Hydrogen Production

Solar-driven photocatalytic green hydrogen (H2) evolution reaction presents a promising route toward solar-to-chemical fuel conversion. However, its efficiency has been hindered by the desynchronization of fast photogenerated charge carriers and slow surface reaction kinetics. This work introduces a paradigm shift in photocatalyst design by focusing on the synchronization of charge transport and surface reactions through the use of twin structures as a unique platform. With CdS twin structure (CdS-T) as a model, the role of twin boundaries in modulating surface reactions and facilitating charge migration is systematically investigated. Utilizing transient absorption (TA) and time-resolved infrared (TRIR) spectroscopies, it is revealed that CdS-T achieves charge separation on a picosecond timescale and, importantly, the surface reaction at the twin boundary with the involvement of holes also occurs within 100 ps to 3 ns. This synchronization of charge donation and surface regeneration significantly enhances the hydrogen evolution process. Accordingly, CdS-T exhibits superior activity for visible light photocatalytic H2 production, withthe H2 production rate of 55.61 mmol h-1 g-1 and remarkable stability (>30 h), outperforming pristine CdS significantly. This study underscores the transformative potential of twin structures in photocatalysis, offering a new avenue to synchronize charge transport and surface reactions.

Synergistic manipulation of sulfur vacancies and palladium doping of In2S3 for enhanced photocatalytic H2 production

In this study, a simple one-pot synthesis process is employed to introduce Pd dopant and abundant S vacancies into In2S3 nanosheets. The optimized Pd-doped In2S3 photocatalyst, with abundant S vacancies, demonstrates a significant enhancement in photocatalytic hydrogen evolution. The joint modification of Pd doping and rich S vacancies on the band structure of In2S3 result in an improvement in both the light absorption capacity and proton reduction ability. It is worth noting that photogenerated electrons enriched by S vacancies can rapidly migrate to adjacent Pd atoms through an efficient transfer path constructed by Pd-S bond, effectively suppressing the charge recombination. Consequently, the dual-defective In2S3 shows an efficient photocatalytic H2 production rate of 58.4 ± 2.0 μmol·h-1. Additionally, further work has been conducted on other ternary metal sulfide, ZnIn2S4. Our findings provide a new insight into the development of highly efficient photocatalysts through synergistic defect engineering.

Photothermal Synergistic Hydrogen Production via a Fly-Ash-made Interfacial Vaporific System

Employing UV-vis spectrum for hydrogen generation and vis-IR spectrum to elevate reaction temperatures and induce phase transitions effectively enhances yield and purifies water, demonstrating a judicious strategy for solar energy utilization. This study presents an interfacial photothermal water splitting system that utilizes all-inorganic, economical industrial by-products known as fly ash cenospheres (FAC) for solar-driven hydrogen generation. In this system, the yield reaches 254.8 µmol h-1 cm-1, representing an 89% augmentation compared to that of the three-phase system. In situ experiments, combined with theoretical calculation, reveal the system's robust light absorption capacity, facilitating rapid gas separation, thus improves the solar-to-hydrogen (STH) efficiency. Furthermore, the system demonstrates strong performance in turbid water and scalability for expansive applications, achieving a hydrogen yield exceeding 50 L h-1 m-2 from various water sources. Facilitating large-scale hydrogen production and water purification, it thereby establishing its potential as a viable solution for sustainable energy generation.

Efficient CO2 Electrocarboxylation Using Dye-Sensitized Photovoltaics

This paper presents the solar-driven electrocarboxylation of 2-bromopyridine (2-BP) with CO2 into high-value-added chemicals 2-picolinic acid (2-PA) using dye-sensitized photovoltaics under simulated sunlight. Using three series-connected photovoltaic modules and an Ag electrode with excellent catalytic performance, a Faraday efficiency (FE) of 33.3% is obtained for 2-PA under mild conditions. The experimental results show that photovoltaics-driven systems for electrocarboxylation conversion of CO2 with heterocyclic halide to afford value-added heterocyclic carboxylic acid are feasible and effective.

What Up with MOFs in Photocatalysis (?): Exploring the Influence of Experimental Conditions on the Reproducibility of Hydrogen Evolution Rates

Metal-organic frameworks (MOFs) are regarded as promising materials for energy applications, particularly in photocatalytic hydrogen (H2) production. This is due to their structural architectures that facilitate charge transfer, and tunable porous and light absorption properties. However, the many characteristics of MOFs including crystal morphology and sizes, surface facets, porosity, light absorption properties, and optical band gaps, can significantly influence their photocatalytic activity, presenting challenges in achieving reproducibility. In this study, we describe the synthesis of five distinct batches of the photoactive MOF, MIL-125-NH2, utilizing different synthetic conditions. Solid-state characterization confirmed the purity, porosity, and light absorption properties of each MOF batch. Each material was then combined with nano sized Ni2P as a cocatalyst, and their photocatalytic activity for H2 evolution was evaluated. We observed variations in their photocatalytic H2 evolution rates, which depended on the batch of MIL-125-NH2 utilized, ranging from the lowest rate of 2980 μmol·h-1·g-1 to the highest of 4327 μmol·h-1·g-1. Notably, different H2 evolution rates were also observed even when MIL-125-NH2 was synthesized under identical synthetic conditions but by different students. Our research highlights the critical relationship between MOF synthesis parameters─such as reaction time, temperature, and precursor concentration─and resulting properties, including particle size, morphology, surface facets, and light absorption characteristics. These factors significantly influence their photocatalytic activity, as evidenced by varying H2 evolution rates. This underscores the importance of optimizing materials synthesis conditions to improve reproducibility and efficiency in photocatalytic applications.

Bifunctional Bi0.98Sm0.02FeO3/g-C3N4 Piezocatalyst for Simultaneous H2 and H2O2 Production

Piezocatalysis portrays a promising alternative for producing hydrogen (H2) and hydrogen peroxide (H2O2) in a clean and safe way, but the simultaneous enhancement of both properties remains challenging. In this study, a BiFeO3-based bifunctional piezocatalytic strategy via Sm doping and g-C3N4 compositing (Bi0.98Sm0.02FeO3/g-C3N4) was proposed for efficient simultaneous H2 and H2O2 production. Benefiting from the synergistic effect between the optimized energy band structure and piezo-generated charges, the performances of hydrogen evolution reaction (HER) and water oxidation reaction (WOR) are both enhanced remarkably. As a result, the evolution rates of BSFO/g-C3N4 for pure water splitting into H2 and H2O2 simultaneously reach 988 and 214 μmol g-1 h-1 without any sacrificial agent, which is 4.6 and 7.6 times higher than those of pure BiFeO3. Theoretical calculations reveal the critical role of this optimization in reducing the adsorption energy barriers of HER and WOR intermediates by factors of 10.83 and 12.38, respectively. This study broadens new insight into the design of efficient piezocatalysts for water splitting.

Toward Spatial Control of Reaction Selectivity on Photocatalysts Using Area-Selective Atomic Layer Deposition on the Model Dual Site Electrocatalyst Platform

Photocatalytic water splitting is a promising route to low-cost, green H2. However, this approach is currently limited in its solar-to-hydrogen conversion efficiency. One major source of efficiency loss is attributed to the high rates of undesired side and back reactions, which are exacerbated by the proximity of neighboring oxidation and reduction sites. Nanoscopic oxide coatings have previously been used to selectively block undesired reactants from reaching active sites; however, a coating encapsulating the entire photocatalyst particle limits activity as it cannot facilitate both half-reactions. In this work, area selective atomic layer deposition (AS-ALD) was used to selectively deposit semipermeable TiO2 films onto model metallic cocatalysts for enhancing reaction selectivity while maintaining a high overall activity. Pt and Au were used as exemplary reduction and oxidation cocatalyst sites, respectively, where Au was deactivated toward ALD growth through self-assembled thiol monolayers while TiO2 was coated onto Pt sites. Electroanalytical measurements of monometallic thin film electrodes showed that the TiO2-encapsulated Pt effectively suppressed undesired H2 oxidation and Fe(II)/Fe(III) redox reactions while still permitting the desired hydrogen evolution reaction (HER). A planar model photocatalyst platform containing patterned interdigitated arrays of Au and Pt microelectrodes was further assessed using scanning electrochemical microscopy (SECM), demonstrating the successful use of AS-ALD to enable local reaction selectivity in a dual-reaction-site (photo)electrocatalytic system. Finally, interdigitated microelectrodes having independent potential control were used to show that selectively deposited TiO2 coatings can suppress the rate of back reactions on neighboring active sites by an order of magnitude compared with uncoated control samples.

Recent Research Progresses and Challenges for Practical Application of Large-Scale Solar Hydrogen Production

Solar hydrogen production is a promising pathway for sustainable CO2-free hydrogen production. It is mainly classified into three systems: photovoltaic electrolysis (PV-EC), photoelectrochemical (PEC) system, and particulate photocatalytic (PC) system. However, it still has trouble in commercialization due to the limitation of performance and economic feasibility in the large-scale system. In this review, the challenges of each large-scale system are, respectively, summarized. Based on this summary, recent approaches to solving these challenges are introduced, focusing on core components, fabrication processes, and systematic designs. In addition, several demonstrations of large-scale systems under outdoor conditions and performances of upscaled systems are introduced to understand the current technical level of solar-driven hydrogen production systems for commercialization. Finally, the future outlooks and perspectives on the practical application of large-scale solar-driven hydrogen production are discussed.

Development and application of ordered membrane electrode assemblies for water electrolysis

With the development of hydrogen energy, there has been increasing attention toward fuel cells and water electrolysis. Among them, the zero-gap membrane electrode assembly (MEA) serves as an important triple-phase reaction site that determines the performance and efficiency of the reaction system. The development of efficient and durable MEAs plays a crucial role in the development of hydrogen energy. Consequently, a great deal of effort has been devoted to developing ordered MEAs that can effectively increase catalyst utilization, maximize triple-phase boundaries, enhance mass transfer and improve stability. The research progress of ordered MEAs in recent advances is highlighted, involving hydrogen fuel cells and low temperature water electrolysis technology. Firstly, the fundamental scientific understanding and structural characteristics of MEAs based on one-dimensional nanostructures such as nanowires, nanotubes and nanofibers are summarized. Then, the classification, preparation and development of ordered MEAs based on three-dimensional structures are summarized. Finally, this review presents current challenges and proposes future research on ordered MEAs and offers potential solutions to overcome these obstacles.