Artificial inorganic leafs for efficient photochemical hydrogen production inspired by natural photosynthesis

3D Printing Photonic Crystals: A Review

Living organisms in nature possess diverse and vibrant structural colors generated from their intrinsic surface micro/nanostructures. These intricate micro/nanostructures can be harnessed to develop a new generation of colorful materials for various fields such as photonics, information storage, display, and sensing. Recent advancements in the fabrication of photonic crystals have enabled the preparation of structurally colored materials with customized geometries using 3D printing technologies. Here, a comprehensive review of the historical development of fabrication methods for photonic crystals is provided. Diverse 3D printing approaches along with the underlying mechanisms, as well as the regulation methods adopted to generate photonic crystals with structural color, are discussed. This review aims to offer the readers an overview of the state-of-the-art 3D printing techniques for photonic crystals, present a guide and considerations to fabricate photonic crystals leveraging different 3D printing methods.

Atomically Precise Regulation of the N-Heterocyclic Microenvironment in Triazine Covalent Organic Frameworks for Coenzyme Photocatalytic Regeneration

Artificial photosynthesis represents a sustainable strategy for accessing high-value chemicals; however, the conversion efficiency is significantly limited by its difficulty in the cycle of coenzymes such as NADH. In this study, we report a series of isostructural triazine covalent organic frameworks (COFs) and explore their N-substituted microenvironment-dependent photocatalytic activity for NADH regeneration. We discovered that the rational alteration of N-heterocyclic species, which are linked to the triazine center through an imine linkage, can significantly regulate both the electron band structure and planarity of a COF layer. This results in different separation efficiencies of the photoinduced electron-hole pairs and electron transfer behavior within and between individual layers. The optimal COF catalyst herein achieves an NADH regeneration capacity of 89% within 20 min, outperforming most of the reported nanomaterial photocatalysts. Based on this, an artificial photosynthesis system is constructed for the green synthesis of a high-value compound, L-glutamate, and its conversion efficiency significantly surpasses the enzymatic approach without the NADH photocatalytic cycle. This work offers new insights into the coenzyme regeneration by means of regulating the distal heterocyclic microenvironment of a COF skeleton, holding great potential for the green photosynthesis of important chemicals.

The Need for Smart Materials in an Expanding Smart World: MXene-Based Wearable Electronics and Their Advantageous Applications

As a result of the transformation of inflexible electronic structures into flexible and stretchy devices, wearable electronics now provide great advantages in a variety of fields, including mobile healthcare sensing and monitoring, human-machine interfaces, portable energy storage and harvesting, and more. Because of their enriched surface functionalities, large surface area, and high electrical conductivity, transition metal nitrides and carbides (also known as MXenes) have recently come to be extensively considered as a group of functioning two-dimensional nanomaterials as well as exceptional fundamental elements for forming flexible electronics devices. This Review discusses the most recent advancements that have been made in the field of MXene-enabled flexible electronics for wearable electronics. The emphasis is placed on extensively established nonstructural features in order to highlight some MXene-enabled electrical devices that were constructed on a nanometric scale. These attributes include devices configured in three dimensions: printed materials, bioinspired structures, and textile and planar substrates. In addition, sample applications in electromagnetic interference (EMI) shielding, energy, healthcare, and humanoid control of machinery illustrate the exceptional development of these nanodevices. The increasing potential of MXene nanoparticles as a new area in next-generation wearable electronic technologies is projected in this Review. The design challenges associated with these electronic devices are also discussed, and possible solutions are presented.

Plant Photocatalysts: Photoinduced Oxidation and Reduction Abilities of Plant Leaf Ashes under Solar Light

Plant leaf ashes were obtained via the high temperature calcination of the leaves of various plants, such as sugarcane, couchgrass, bracteata, garlic sprout, and the yellowish leek. Although the photosynthesis systems in plant leaves cannot exist after calcination, minerals in these ashes were found to exhibit photochemical activities. The samples showed solar light photocatalytic oxidation activities sufficient to degrade methylene blue dye. They were also shown to possess intrinsic dehydrogenase-like activities in reducing the colorless electron acceptor 2,3,5-triphenyltetrazolium chloride to a red formazan precipitate under solar light irradiation. The possible reasons behind these two unreported phenomena were also investigated. These ashes were characterized using a combination of physicochemical techniques. Moreover, our findings exemplify how the soluble and insoluble minerals in plant leaf ashes can be synergistically designed to yield next-generation photocatalysts. It may also lead to advances in artificial photosynthesis and photocatalytic dehydrogenase.

Recent advances and progress in biotemplate catalysts for electrochemical energy storage and conversion

Complex structures and morphologies in nature endow materials with unexpected properties and extraordinary functions. Biotemplating is an emerging strategy for replicating nature structures to obtain materials with unique morphologies and improved properties. Recently, efforts have been made to use bio-inspired species as a template for producing morphology-controllable catalysts. Fundamental information, along with recent advances in biotemplate metal-based catalysts are presented in this review through discussions of various structures and biotemplates employed for catalyst preparation. This review also outlines the recent progress on preparation routes of biotemplate catalysts and discusses how the properties and structures of these templates play a crucial role in the final performance of metal-based catalysts. Additionally, the application of bio-based metal and metal oxide catalysts is highlighted for various key energy and environmental technologies, including photocatalysis, fuel cells, and lithium batteries. Biotemplate metal-based catalysts display high efficiency in several energy and environmental systems. Note that this review provides guidance for further research in this direction.

Plant Leaf-Inspired Separators with Hierarchical Structure and Exquisite Fluidic Channels for Dendrite-Free Lithium Metal Batteries

Lithium (Li) metal batteries are among the most promising devices for high energy storage applications but suffer from severe and irregular Li dendrite growth. Here, it is demonstrated that the issue can be well tackled by precisely designing the leaf-like membrane with hierarchical structure and exquisite fluidic channels. As a proof of concept, plant leaf-inspired membrane (PLIM) separators are prepared using natural attapulgite nanorods. The PLIM separators feature super-electrolyte-philicity, high thermal stability and high ion-selectivity. Thus, the separators can guide uniform and directed Li growth on the Li anode. The Li//PLIM//Li cell with limited Li anode shows high Coulombic efficiency and cycling stability over 1500 h with small overpotential and interface impedance. The Li//PLIM//S battery exhibits high initial capacity (1352 mAh g-1 ), cycling stability (0.019% capacity decay per cycle at 1 C over 500 cycles), rate performance (673 mAh g-1 at 4 C), and high operating temperature (65 °C). The separators can also effectively improve reversibility and cycling stability of the Li/Li cell and Li//LFP battery with carbonate-based electrolyte. As such, this work provides fresh insights into the design of bioinspired separators for dendrite-free metal batteries.

A photo-switchable molecular capsule: sequential photoinduced processes

The metastable trilacunary heteropolyoxomolybdate [PMo₉O₃₁(py)₃]^3- - {PMo₉}; py = pyridine) and the ditopic pyridyl bearing diarylethene (DAE) (C₂₅H₁₆N₂F₆S₂) self-assemble via a facile ligand replacement methodology to yield the photo-active molecular capsule [(PMo₉O₃₁)₂(DAE)₃]^6-. The spatial arrangement and conformation of the three DAE ligands are directed by the surface chemistry of the molecular metal oxide precursor with exclusive ligation of the photo-active antiparallel rotamer to the polyoxometalate (POM) while the integrity of the assembly in solution has been verified by a suite of spectroscopic techniques. Electrocyclisation of the three DAEs occurs sequentially and has been investigated using a combination of steady-state and time-resolved spectroscopies with the discovery of a photochemical cascade whereby rapid photoinduced ring closure is followed by electron transfer from the ring-closed DAE to the POM in the latent donor-acceptor system on subsequent excitation. This interpretation is also supported by computational and detailed spectroelectrochemical analysis. Ring-closing quantum yields were also determined using a custom quantum yield determination setup (QYDS), providing insight into the impact of POM coordination on these processes.

CdS-based artificial leaf for photocatalytic hydrogen evolution and simultaneous degradation of biological wastewater

Rational design of all-solid-state Z-scheme heterojunction with advanced structure is essential for boosting photocatalytic efficiency. Herein, we design and fabricate a novel Z-scheme photocatalyst with leaf architecture (named artificial leaf) via a simple dipping-calcination (DC) process followed by a successive ionic layer adsorption and reaction (SILAR) strategy. The prepared artificial leaf, composing of CdS, InVO₄, and BiVO₄, holds advanced leaf-like structure and Z-scheme electron transfer pathway. As a result, this novel artificial leaf exhibits outstanding capability for the harvesting of visible light and superior efficiency for the separation of photogenerated electron-hole pairs, as well as remarkably enhanced photocatalytic performance and stability for H₂ evolution (with the rate of 5033 μm g^-1∙h^-1) and pollution degradation (46% pollution can be degraded within 3 h).

Highly efficient and selective modification of lignin towards optically designable and multifunctional lignocellulose nanopaper for green light-management applications

Transparent lignocellulose nanopaper (LNP) has been demonstrated to be a promising candidate light-management material for next-generation optical engineering applications. Similar to its role in plant cell walls, lignin serves as a vital functional component in LNP matrices. However, its intrinsic light absorption property renders LNP undesirable for a range of optical management systems. Here, a highly efficient, controllable and ecofriendly lignin modification strategy is developed for modulating the optical performance of LNPs by taking advantage of the beneficial synergistic effect of H₂O₂ and UV light in selectively eliminating lignin chromophores. The obtained lignin-modified LNP features not only a high visible light transmittance (89%) but also a high haze (90%) and excellent UV-shielding capacity, owing to the well-preserved lignin aromatic skeleton structures after lignin modification. Furthermore, patterning is easily achieved on hot-pressing-induced densified LNPs through a selective lignin modification approach, which endows LNPs with intriguing optical designability. Benefitting from the multifunctionality of lignin components for nanopaper matrices, patterned LNPs demonstrate outstanding water and thermal stability, barrier properties, durability and biodegradability, which are of great significance for practical applications. Furthermore, we demonstrate the great applicability of this optically designable and multifunctional LNP as a light-management material for energy efficient buildings by highlighting its attractive sun- and indoor- light managing effects, effective thermal insulation, as well as superior durability for long-term use. In combination with its efficient, ecofriendly and controllable production, this novel high-performing LNP holds great potential in many other applications that require light-management structural materials, such as optoelectronic and sensing devices.

Biotemplated CdS Nano-Aggregate Networks for Highly Effective Visible-Light Photocatalytic Hydrogen Production

In the last few decades, many new synthesis techniques have been developed in order to obtain an effective visible-light responsive photocatalyst for hydrogen production by water splitting. Among these new approaches, the biotemplated synthesis method has aroused much attention because of its unique advantages in preparing materials with special morphology and structure. In this work, Hydrilla verticillata (L. f.) Royle was used as a biotemplate to synthesize a CdS photocatalyst. The as-synthesized sample had the microstructure of nano-scaled aggregate networks and its activity for photocatalytic hydrogen production was six times higher than that of CdS synthesized without a template in an Na₂S-Na₂SO₃ sacrificial system. The use of Pt and PdS as cocatalysts further improved the hydrogen production rate to 14.86 mmol/g·h under visible-light (λ ≥ 420 nm) irradiation, so the hydrogen production can be directly observed by the naked eye. The results of characterization showed that the as-synthesized CdS photocatalyst has a high specific surface area and narrow band gap, which is favorable for light absorption and photocatalytic reaction. This work provides a new way to search for efficient visible-light catalysts and confirms the uniqueness of a biotemplated synthesis method in obtaining specially structured materials.

Bio-inspired graphene-based nano-systems for biomedical applications

The increasing demands of environmentally sustainable, affordable, and scalable materials have inspired researchers to explore greener nanosystems of unique properties which can enhance the performance of existing systems. Such nanosystems, extracted from nature, are state-of-art high-performance nanostructures due to intrinsic hierarchical micro/nanoscale architecture and generous interfacial interactions in natural resources. Among several, bio-inspired nanosystems graphene nanosystems have emerged as an essential nano-platform wherein a highly electroactive, scalable, functional, flexible, and adaptable to a living being is a key factor. Preliminary investigation project bio-inspired graphene nanosystems as a multi-functional nano-platform suitable for electronic devices, energy storage, sensors, and medical sciences application. However, a broad understanding of bio-inspired graphene nanosystems and their projection towards applied application is not well-explored yet. Considering this as a motivation, this mini-review highlights the following; the emergence of bio-inspired graphene nanosystems, over time development to make them more efficient, state-of-art technology, and potential applications, mainly biomedical including biosensors, drug delivery, imaging, and biomedical systems. The outcomes of this review will certainly serve as a guideline to motivate scholars to design and develop novel bio-inspired graphene nanosystems to develop greener, affordable, and scalable next-generation biomedical systems.

Titanium Vacancies in TiO2 Nanofibers Enable Highly Efficient Photo-Driven Seawater Splitting

Photo-driven seawater splitting is considered as one of the most promising techniques for sustainable hydrogen production. However, the high salinity of seawater would deactivate catalysts and consumes the photogenerated carriers. Metal vacancies in metal oxide semiconductors are critical to directed electron transfer and high salinity resistance, thus desirable but remains a challenge. We demonstrate a facile controllable calcination approach to synthesize TiO 2 nanofibers with rich Ti-vacancies with excellent photo/electro performances and long-time stability in photo-driven seawater splitting, including photocatalysis and photoelectrocatalysis. Experimental measurements and theoretical calculations reveal the formation of titanium vacancies, as well as its unidirectional electron trap and superior H + adsorption ability for efficient charge transfer and corrosion resistance of seawater. Therefore, the characteristics and mechanism have been proposed at an atomic-/nanoscale to clarify the generation of titanium vacancies and the corresponding interfacial electron transfer.

Remarkable Rate of Water Evaporation through Naked Veins of Natural Tree Leaves

In the form of leaves, nature designs the finest photothermal evaporators, and the tremendous evaporation efficiency of leaves is supported by a precisely designed network of veins. Here, we have demonstrated that the vein network of a natural leaf can be extracted through a simple water-assisted digestion process and exploited for low-energy steam generation. The naked leaf veins exhibit a remarkable flux (evaporation rate, 1.5 kg·m-2·h-1) of capillary evaporation under ambient conditions (25 °C and 30% RH), close to the photothermal material-based evaporators reported in the recent literature. Even inside a dark box, naked veins exhibit an evaporation rate up to 4.5 kg·m-2·h-1 (at 30% relative humidity (RH) and a wind speed of 22 km·h-1). The mechanistic studies performed with variable atmospheric conditions (temperature, humidity, and wind speed) suggest the evaporation process through the naked veins to be a kinetic-limited process. Naked veins with remarkable evaporation efficiency are found to be suitable for applications like water desalination and streaming potential harvesting. Experiments with the naked veins also unveiled that the biofluidic channels in leaves not only exhibit the characteristics of surface charge-governed ionic transport but also support an exceptional water transport velocity of 1444 μm·s-1.

Gated Dissipative Dynamic Artificial Photosynthetic Model Systems

Gated dissipative artificial photosynthetic systems modeling dynamically modulated environmental effects on the photosynthetic apparatus are presented. Two photochemical systems composed of a supramolecular duplex scaffold, a photosensitizer-functionalized strand (photosensitizer is Zn(II)protoporphyrin IX, Zn(II)PPIX, or pyrene), an electron acceptor bipyridinium (V²⁺)-modified strand, and a nicking enzyme (Nt.BbvCI) act as functional assemblies driving transient photosynthetic-like processes. In the presence of a fuel strand, the transient electron transfer quenching of the photosensitizers, in each of the photochemical systems, is activated. In the presence of a sacrificial electron donor (mercaptoethanol) and continuous irradiation, the resulting electron transfer process in the Zn(II)PPIX/V²⁺ photochemical module leads to the transient accumulation and depletion of the bipyridinium radical-cation (V·⁺) product, and in the presence of ferredoxin-NADP⁺ reductase and NADP⁺, to the kinetically modulated photosynthesis of NADPH. By subjecting the mixture of two photochemical modules to one of two inhibitors, the gated transient photoinduced electron transfer in the two modules is demonstrated. Such gated dissipative process highlights its potential as an important pathway to protect artificial photosynthetic module against overdose of irradiance and to minimize photodamage.

Branched In2O3 Mesocrystal of Ordered Architecture Derived from the Oriented Alignment of a Metal-Organic Framework for Accelerated Hydrogen Evolution over In2O3-ZnIn2S4

It is fascinating yet challenging to assemble anisotropic nanowires into ordered architectures of high complexity and intriguing functions. We exploited a facile strategy involving oriented etching of a metal-organic fragment (MOF) to advance the rational design of highly ordered nanostructures. As a proof of concept, a microscale MIL-68(In) single crystal was etched with a K₃[Co(CN)₆] solution to give a microtube composed of aligned MIL-68(In) nanorods. Annealing such a MIL-68(In) microtube readily created an unprecedented branched In₂O₃ mesocrystal by assembly of In₂O₃ nanorods aligned in order. The derived ordered-In₂O₃-ZnIn₂S₄ is more efficient in catalyzing visible-light-driven H₂ evolution (8753 μmol h^-1 g^-1) outperforming the disordered-In₂O₃-ZnIn₂S₄ counterpart (2700 μmol h^-1 g^-1) as well as many other state-of-the-art ZnIn₂S₄-based photocatalysts. The ordered architecture significantly boosts the short-range electron transfer in an In₂O₃-ZnIn₂S₄ heterojunction but has a negligible impact on the long-range electron transfer among In₂O₃ mesocrystals. The density functional theory (DFT) calculation reveals that the oriented etching is achieved by the selective binding of the [Co(CN)₆]^3- etchant on the (110) plane of MIL-68(In), which can drag the In atoms out of the framework in order. Our findings could broaden the technical sense toward advanced photocatalyst design and impose scientific impacts on unveiling how ordered photosystems operate.

Hierarchically structured porous materials: synthesis strategies and applications in energy storage

To address the growing energy demands of sustainable development, it is crucial to develop new materials that can improve the efficiency of energy storage systems. Hierarchically structured porous materials have shown their great potential for energy storage applications owing to their large accessible space, high surface area, low density, excellent accommodation capability with volume and thermal variation, variable chemical compositions and well controlled and interconnected hierarchical porosity at different length scales. Porous hierarchy benefits electron and ion transport, and mass diffusion and exchange. The electrochemical behavior of hierarchically structured porous materials varies with different pore parameters. Understanding their relationship can lead to the defined and accurate design of highly efficient hierarchically structured porous materials to enhance further their energy storage performance. In this review, we take the characteristic parameters of the hierarchical pores as the survey object to summarize the recent progress on hierarchically structured porous materials for energy storage. This is the first of this kind exclusively to survey the performance of hierarchically structured porous materials from different porous characteristics. For those who are not familiar with hierarchically structured porous materials, a series of very significant synthesis strategies of hierarchically structured porous materials are firstly and briefly reviewed. This will be beneficial for those who want to quickly obtain useful reference information about the synthesis strategies of new hierarchically structured porous materials to improve their performance in energy storage. The effect of different organizational, structural and geometric parameters of porous hierarchy on their electrochemical behavior is then deeply discussed. We outline the existing problems and development challenges of hierarchically structured porous materials that need to be addressed in renewable energy applications. We hope that this review can stimulate strong intuition into the design and application of new hierarchically structured porous materials in energy storage and other fields.

Metal-Organic Framework-Plant Nanobiohybrids as Living Sensors for On-Site Environmental Pollutant Detection

Photoluminescent metal-organic frameworks (MOFs) were grown in a living plant (Syngonium podophyllum) via immersing their roots in an aqueous solution of disodium terephthalate and terbium chloride hexahydrate sequentially for 12 h without affecting their viability. Then, app-assisted living MOF-plant nanobiohybrids were used for the detection of various toxic metal ions and organic pollutants. Their performance and sensing mechanism were also evaluated. The results demonstrated that the living plants served as self-powered preconcentrators via their passive fluid transport systems and accumulated the pollutants around the embedded MOFs, resulting in relative changes in fluorescence intensity. Therefore, the living MOF-plant nanobiohybrids initiate superior selectivity and sensitivity (0.05-0.5 μM) in water for Ag⁺, Cd²⁺, and aniline with a "turn-up" fluorescence response and for Fe³⁺ and Cu²⁺ with "turn-down" fluorescence response in the linear range of 0.05-10 μM with excellent precision and accuracy of 5 and 10%, respectively. With the easy-to-read visual signals under ultraviolet light, the app translates plant luminescent signals into digital information on a smartphone for on-site monitoring of environmental pollutants with high sensitivity and specificity. These results suggest that interfacing synthetic and living materials may contribute to the development of smart sensors for on-site environmental pollutant sensing with high accuracy.

Spatial Heterojunction in Nanostructured TiO2 and Its Cascade Effect for Efficient Photocatalysis

A highly efficient photoenergy conversion is strongly dependent on the cumulative cascade efficiency of the photogenerated carriers. Spatial heterojunctions are critical to directed charge transfer and, thus, attractive but still a challenge. Here, a spatially ternary titanium-defected TiO₂@carbon quantum dots@reduced graphene oxide (denoted as V_Ti@CQDs@rGO) in one system is shown to demonstrate a cascade effect of charges and significant performances regarding the photocurrent, the apparent quantum yield, and photocatalysis such as H₂ production from water splitting and CO₂ reduction. A key aspect in the construction is the technologically irrational junction of Ti-vacancies and nanocarbons for the spatially inside-out heterojunction. The new "spatial heterojunctions" concept, characteristics, mechanism, and extension are proposed at an atomic-/nanoscale to clarify the generation of rational heterojunctions as well as the cascade electron transfer.

3D structured materials and devices for artificial photosynthesis

Artificial photosynthesis is an effective way to convert solar energy into fuels, which is of great significance to energy production and reduction of atmospheric CO₂ content. In recent years, 3D structured artificial photosynthetic system has made great progress as an effective design strategy. This review first highlights several typical mechanisms for improved artificial photosynthesis with 3D structures: improved light harvesting, mass transfer and charge separation. Then, we summarize typical examples of 3D structured artificial photosynthetic systems, including bioinspired structures, photonic crystals (PC), designed photonic structures (PC coupling structure, plasmon resonance structure, optical resonance structure, metamaterials), 3D-printed systems, nanowire integrated systems and hierarchical 3D structures. Finally, we discuss the problems and challenges to the application and development of 3D artificial photosynthetic system and the possible trends of future development. We hope this review can inspire more progress in the field of artificial photosynthesis.

Nanobiohybrids: Materials approaches for bioaugmentation

Nanobiohybrids, synthesized by integrating functional nanomaterials with living systems, have emerged as an exciting branch of research at the interface of materials engineering and biological science. Nanobiohybrids use synthetic nanomaterials to impart organisms with emergent properties outside their scope of evolution. Consequently, they endow new or augmented properties that are either innate or exogenous, such as enhanced tolerance against stress, programmed metabolism and proliferation, artificial photosynthesis, or conductivity. Advances in new materials design and processing technologies made it possible to tailor the physicochemical properties of the nanomaterials coupled with the biological systems. To date, many different types of nanomaterials have been integrated with various biological systems from simple biomolecules to complex multicellular organisms. Here, we provide a critical overview of recent developments of nanobiohybrids that enable new or augmented biological functions that show promise in high-tech applications across many disciplines, including energy harvesting, biocatalysis, biosensing, medicine, and robotics.

Au nanozyme-driven antioxidation for preventing frailty

From senescence and frailty that may result from various biological, mechanical, nutritional, and metabolic processes, the human body has its own antioxidant defense enzymes to remove by-products of oxygen metabolism, and if unregulated, can cause several types of cell damage. Herein, an antioxidant, artificial nanoscale enzyme, called nanozyme (NZs), is introduced that is composed of Au nanoparticles (NPs) synthesized with a mixture of two representative phytochemicals, namely, gallic acid (GA) and isoflavone (IF), referred to as GI-Au NZs. Their unique antioxidant and anti-aging effects are monitored using Cell Counting Kit-8 and senescence-associated β-galactosidase assays on neonatal human dermal fibroblasts (nHDFs). Furthermore, alterations in epidermal thickness and SOD activity are measured under ultraviolet light to investigate the effects of the topical application of NZs on the histological structure and antioxidant activity in hairless mice skin. Then, hepatotoxicity and nephrotoxicity in the hairless mice are monitored. It is concluded that the NZs can effectively prevent serial passage-induced senescence in nHDFs, as well as oxidative stress in mice skin, suggesting a range of strategies to further develop novel therapeutics for acute frailty.

Sunlight-Mediated Thiol-Ene/Yne Click Reaction: Synthesis and DNA Transfection Efficiency of New Cationic Lipids

The design of green synthetic reaction conditions is very challenging, especially for biomaterials, but worthwhile if the compounds can be easily synthesized in the aqueous medium. Herein, we report the development of sunlight-mediated thiol-ene/yne click reaction in the presence of a catalytic amount of tert-butyl hydroperoxide (TBHP) in an aqueous medium. The optimized reaction conditions were successfully applied to synthesize a series of small molecules and lipids in a single step in the aqueous medium. The synthetic cationic lipid/co-lipid formed positively charged stable nanosized liposomes that effectually bind with the genetic materials. The in vitro DNA transfection and cellular uptake assays showed that the synthesized cationic lipids have comparable efficiency to commercially available Lipofectamine 2000. This mild synthetic strategy can also be used for smart design of novel or improvement of prevailing lipid-based nonviral gene delivery systems. Such chemical transformations in the aqueous medium are more environment-friendly than other reported thiol-ene/yne click reactions performed in an organic solvent medium.

Construction of MnO2 Artificial Leaf with Atomic Thickness as Highly Stable Battery Anodes

The leaf-like structure is a classic and robust structure and its unique vein support can reduce structural instability. However, biomimetic leaf structures on the atomic scale are rarely reported due to the difficulty in achieving a stable vein-like support in a mesophyll-like substrate. A breathable 2D MnO₂ artificial leaf is first reported with atomic thickness by using a simple and mild one-step wet chemical method. This homogeneous ultrathin leaf-like structure comprises of vein-like crystalline skeleton as support and amorphous microporous mesophyll-like nanosheet as substrate. When used as an anode material for lithium ion batteries, it first solves the irreversible capacity loss and poor cycling issue of pure MnO₂ , which delivers high capacity of 1210 mAh g^-1 at 0.1 A g^-1 and extremely stable cycle life over 2500 cycles at 1.0 A g^-1 . It exhibits the most outstanding cycle life of pure MnO₂ and even comparable to the most MnO₂ -based composite electrode materials. This biomimetic design provides important guidelines for precise control of 2D artificial systems and gives a new idea for solving poor electrochemical stability of pure metal oxide electrode materials.

Photosensitized H2 Evolution and NADPH Formation by Photosensitizer/Carbon Nitride Hybrid Nanoparticles

The broadband C₃N₄ semiconductor absorbs in the UV region, λ = 330-380 nm, a feature limiting its application for light-to-energy conversion. The unique surface adsorption properties of C₃N₄ allow, however, the binding of a photosensitizer, operating in the visible-solar spectrum to the surface of C₃N₄. Coupling of the energy levels of the photosensitizer with the energy levels of C₃N₄ allows effective photoinduced electron-transfer quenching and subsequent charge separation in the hybrid structures. Two methods to adsorb a photosensitizer on the C₃N₄ nanoparticles are described. One is exemplified by the adsorption of Zn(II)-protoporphyrin IX on C₃N₄ using π-π interactions. The second method utilizes the specific binding interactions of single-stranded nucleic acids on C₃N₄ and involves the binding of a Ru(II)-tris-bipyridine-modified nucleic acid on the C₃N₄ nanoparticles. Effective electron-transfer quenching of the photoexcited photosensitizers by C₃N₄ proceeds in the two hybrid systems. The two hybrid photosystems induce the effective photosensitized reduction of N,N'-dimethyl-4,4'-bipyridinium, MV²⁺, to MV^+•, in the presence of Na₂EDTA as a sacrificial electron donor. The generation of MV^+• is ca. 5-fold higher as compared to the formation of MV^+• in the presence of the photosensitizer alone (in the absence of C₃N₄). The effective generation of MV^+• in the photosystems is attributed to the efficient quenching of the photosensitizers, followed by effective charge separation of the electrons in the conduction band of C₃N₄ and the holes in the oxidized photosensitizer. The subsequent transfer of the conduction-band electrons to MV²⁺ and the oxidation of Na₂EDTA by the oxidized photosensitizers lead to the effective formation of MV^+•. The photogenerated MV^+• by the two hybrid photosystems is used to catalyze H₂ evolution in the presence of Pt nanoparticle catalysts and to mediate the reduction of NADP⁺ to NADPH, in the presence of ferredoxin-NADP⁺ reductase, FNR. The ability to couple the photogenerated NADPH to drive NADP⁺-dependent biocatalytic transformations is demonstrated.

Tungsten oxide nanostructures and nanocomposites for photoelectrochemical water splitting

Hydrogen production from photoelectrochemical (PEC) water splitting using semiconductor photocatalysts has attracted great attention to realize clean and renewable energy from solar energy. The visible light response of WO3 with a long hole diffusion length (∼150 nm) and good electron mobility (∼12 cm2 V-1 s-1) makes it suitable as the photoanode. However, WO3 suffers from issues including rapid recombination of photoexcited electron-hole pairs, photo-corrosion during the photocatalytic process due to the formation of peroxo-species, sluggish kinetics of photogenerated holes, and slow charge transfer at the semiconductor/electrolyte interface. This work highlights the approaches to overcome these drawbacks of WO3 photoanodes, including: (i) the manipulation of nanostructured WO3 photoanodes to decrease the nanoparticle size to promote hole migration to the WO3/electrolyte interface which benefits the charge separation; (ii) doping or introducing oxygen vacancies to improve electrical conductivity; exposing high energy crystal surfaces to promote the consumption of photogenerated holes on the high-active crystal face, thereby suppressing the recombination of photogenerated electrons and holes; (iii) decorating with co-catalysts to reduce the overpotential which inhibits the formation of peroxo-species; (iv) other methods such as coupling with narrow band semiconductors to accelerate the charge separation and controlling the crystal phase via annealing to reduce defects. These approaches are reviewed with detailed examples.

Electronic Integration and Thin Film Aspects of Au-Pd/rGO/TiO2 for Improved Solar Hydrogen Generation

In the present work, we have synthesized noble bimetallic nanoparticles (Au-Pd NPs) on a carbon-based support and integrated with titania to obtain Au-Pd/C/TiO₂ and Au-Pd/rGO/TiO₂ nanocomposites using an ecofriendly hydrothermal method. Here, a 1:1 (w/w) Au-Pd bimetallic composition was dispersed on (a) high-surface-area (3000 m² g^-1) activated carbon (Au-Pd/C), prepared from a locally available plant source (in Assam, India), and (b) reduced graphene oxide (rGO) (Au-Pd/rGO); subsequently, they were integrated with TiO₂. The shift observed in Raman spectroscopy demonstrates the electronic integration of the bimetal with titania. The photocatalytic activity of the above materials for the hydrogen evolution reaction was studied under 1 sun conditions using methanol as a sacrificial agent in a powder form. The photocatalysts were also employed to prepare a thin film by the drop-casting method. Au-Pd/rGO/TiO₂ exhibits 43 times higher hydrogen (H₂) yield in the thin film form (21.50 mmol h^-1 g^-1) compared to the powder form (0.50 mmol h^-1 g^-1). On the other hand, Au-Pd/C/TiO₂ shows 13 times higher hydrogen (H₂) yield in the thin film form (6.42 mmol h^-1 g^-1) compared to the powder form (0.48 mmol h^-1 g^-1). While powder forms of both catalysts show comparable activity, the Au-Pd/rGO/TiO₂ thin film shows 3.4 times higher activity than that of Au-Pd/C/TiO₂. This can be ascribed to (a) an effective separation of photogenerated electron-hole pairs at the interface of Au-Pd/rGO/TiO₂ and (b) the better field effect due to plasmon resonance of the bimetal in the thin film form. The catalytic influence of the carbon-based support is highly pronounced due to synergistic binding interaction of bimetallic nanoparticles. Further, a large amount of hydrogen evolution in the film form with both catalysts (Au-Pd/C/TiO₂ and Au-Pd/rGO/TiO₂) reiterates that charge utilization should be better compared to that in powder catalysts.

Artificial Photosynthesis with Electron Acceptor/Photosensitizer-Aptamer Conjugates

Sequence-specific aptamers act as functional scaffolds for the assembly of photosynthetic model systems. The Ru(II)-tris-bipyridine photosensitizer is conjugated by different binding modes to the antityrosinamide aptamer to yield a set of photosensitizer-aptamer binding scaffolds. The N-methyl-N'-(3-aminopropane)-4,4'-bipyridinium electron acceptor, MV²⁺, is covalently linked to tyrosinamide, TA, to yield the conjugate TA-MV²⁺. The tyrosinamide unit in TA-MV²⁺ acts as a ligand for anchoring TA-MV²⁺ to the Ru(II)-tris-bipyridine-aptamer scaffold, generating the diversity of photosensitizer-aptamer/electron acceptor supramolecular conjugates. Effective electron transfer quenching in the photosynthetic model systems is demonstrated, and the quenching efficiencies are controlled by the structural features of the conjugates. The redox species generated by the photosensitizer-aptamer/electron acceptor supramolecular systems mediate the ferredoxin-NADP⁺ reductase, FNR, catalyzed synthesis of NADPH, and the Pt-nanoparticle-catalyzed evolution of hydrogen (H₂). The novelty of the study rests on the unprecedented use of aptamer scaffolds as functional units for organizing photosynthetic model systems.

Leaf-inspired multiresponsive MXene-based actuator for programmable smart devices

Natural leaves, with elaborate architectures and functional components, harvest and convert solar energy into chemical fuels that can be converted into energy based on photosynthesis. The energy produced leads to work done that inspired many autonomous systems such as light-triggered motion. On the basis of this nature-inspired phenomenon, we report an unprecedented bilayer-structured actuator based on MXene (Ti3C2T x )-cellulose composites (MXCC) and polycarbonate membrane, which mimic not only the sophisticated leaf structure but also the energy-harvesting and conversion capabilities. The bilayer actuator features multiresponsiveness, low-power actuation, fast actuation speed, large-shape deformation, programmable adaptability, robust stability, and low-cost facile fabrication, which are highly desirable for modern soft actuator systems. We believe that these adaptive soft systems are attractive in a wide range of revolutionary technologies such as soft robots, smart switch, information encryption, infrared dynamic display, camouflage, and temperature regulation, as well as human-machine interface such as haptics.

Efficient Separation of Ethanol-Methanol and Ethanol-Water Mixtures Using ZIF-8 Supported on a Hierarchical Porous Mixed-Oxide Substrate

This work reports a new approach for the synthesis of a zeolitic imidazolate framework (ZIF-8) composite. It employs the direct growth of the crystalline ZIF-8 on a mixed-metal oxide support TiO₂-SiO₂ (TSO), which mimics the porous structure of Populus nigra. Using the natural leaf as a template, the TSO support was prepared using a sol-gel method. The growth of the ZIF-8 layer on the TSO support was carried out by the seeds and second growth method. This method facilitates the homogeneous dispersion of ZIF-8 crystals at the surface of the TSO composite. The ZIF-8@TSO composite adsorbs methanol selectively, mainly due to the hierarchical porous structure of the mixed oxide support. As compared with the as-synthesized ZIF-8, a 50% methanol uptake is achieved in the ZIF-8@TSO composite, with only 25 wt % ZIF-8 loading. IAST simulations show that the ZIF-8@TSO composite has a preferential adsorption toward methanol when using an equimolar methanol-ethanol mixture. An opposite behavior is observed for the as-synthesized ZIF-8. The results show that combining MOFs and mixed-oxide supports with bioinspired structures opens opportunities for synthesizing new materials with unique and enhanced adsorption and separation properties.

Core-shell nanomaterials: Applications in energy storage and conversion

Materials with core-shell structures have attracted increasing attention in recent years due to their unique properties and wide applications in energy storage and conversion systems. Through reasonable adjustments of their shells and cores, various types of core-shell structured materials can be fabricated with favorable properties that play significant roles in energy storage and conversion processes. The core-shell material can provide an effective solution to the current energy crisis. Various synthetic strategies used to fabricate core-shell materials, including the atomic layer deposition, chemical vapor deposition and solvothermal method, are briefly mentioned here. A state-of-the -art review of their applications in energy storage and conversion is summarized. The involved energy storage includes supercapacitors, li-ions batteries and hydrogen storage, and the corresponding energy conversion technologies contain quantum dot solar cells, dye-sensitized solar cells, silicon/organic solar cells and fuel cells. In addition, the correlation between the core-shell structures and their performance in energy storage and conversion is introduced, and this finding can provide guidance in designing original core-shell structures with advanced properties.

Microemulsion-Assisted Self-Assembly and Synthesis of Size-Controlled Porphyrin Nanocrystals with Enhanced Photocatalytic Hydrogen Evolution

Design and engineering of highly efficient light-harvesting nanomaterial systems to emulate natural photosynthesis for maximizing energy conversion have stimulated extensive efforts. Here we present a new class of photoactive semiconductor nanocrystals that exhibit high-efficiency energy transfer for enhanced photocatalytic hydrogen production under visible light. These nanocrystals are formed through noncovalent self-assembly of In(III) meso-tetraphenylporphine chloride (InTPP) during microemulsion assisted nucleation and growth process. Through kinetic control, a series of uniform nanorods with controlled aspect ratio and high crystallinity have been fabricated. Self-assembly of InTPP porphyrins results in extensive optical coupling and broader coverage of the visible spectrum for efficient light harvesting. As a result, these nanocrystals display excellent photocatalytic hydrogen production and photostability under the visible light in comparison with the commercial InTPP porphyrin powders.

Thiol-ene polymerization for hierarchically porous hybrid materials by adding degradable polycaprolactone for adsorption of bisphenol A

Hierarchically porous materials with multiple pore structures have the potential application in catalysis, separation or bioengineering. A concept was introduced to design and fabricate hierarchically porous hybrid materials (HPHMs) simultaneously containing mesopores and macropores. The proof-of-concept design was demonstrated by fabrication of several kinds of hybrid materials by adding degradable polycaprolactone (PCL) additive, which was simple and easy-operating. The specific surface areas of HPHMs prepared with polyhedral oligomeric vinylsilsesquioxanes (vinylPOSS) and 1,4-dithiothreitol (DTT) could reach 727 m²/g by adding 25% PCL additive, while the HPHMs were imperforate prior to degradation of PCL. The characterization further indicated that the macropores could be controlled by the amount of PCL additive. Moreover, the porous properties of HPHMs were influenced by the molecular weight of PCL. Other dithiols compounds were also successful in preparing HPHMs with high specific surface areas over 400 m²/g. Due to hydrophobic interaction and hydrogen bond interaction, the HPHM exhibited good adsorption ability for bisphenol A (BPA) in aqueous solution. Adsorption equilibrium could be achieved within 30 min, and the adsorption capacity was up to 157.4 mg/g. Meanwhile, the removal efficiency was found to be 95.37% for BPA.

Construction of an artificial inorganic leaf CdS–BiVO4 Z-scheme and its enhancement activities for pollutant degradation and hydrogen evolution

An artificial inorganic leaf CdS–BiVO₄ micro-nano Z-scheme photocatalytic system was synthesized by the BT–DC–SILAR method taking a leaf as a template.

Hierarchical structured Mn2O3 nanomaterials with excellent electrochemical properties for lithium ion batteries

A series of Mn₂O₃ nanomaterials with hierarchical porous structures was synthesized using three types of leaves as templates. In addition to their different morphologies, different porous nanostructures were achieved by choosing different leaves. The Mn₂O₃ nanomaterial prepared by using gingko leaves as a template provides a larger pore volume and a higher Brunauer–Emmett–Teller (BET) surface area. At the same time, this material also displays excellent electrochemical performance, that is, the specific capacities are 1274.6 mA h g⁻¹ after 300 cycles and 381.5 mA h g⁻¹ at current densities of 300 and 3000 mA g⁻¹, respectively.

A series of Mn₂O₃ nanomaterials with hierarchical porous structures was synthesized using three types of leaves as templates.

Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

With an increased focus on light energy to facilitate catalytic processes, photocatalysts have been intensively studied for a wide range of energy and environmental applications. In this report, we describe the use of chemically dehydrated leaves as sacrificial foam-like templates for the growth of monolithic macrostructured semiconducting zinc oxide and nickel or cobalt doped zinc oxide materials. The composition and structure of these templated zinc oxides were characterized using X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. Optical properties were examined using solid-state UV–vis diffuse reflectance spectroscopy. The metal-doped ZnO materials have enhanced visible absorption and lower band gaps as compared to ZnO. The botanically templated ZnO materials retain the macroscopic cellular form of the leaf template with fused nanoparticle walls. Their UV photocatalytic oxidative abilities were investigated using methylene blue dye degradation in air. The leaf templated zinc oxides degrade ~85% of methylene blue dye with 30 min of UV illumination. Nickel and cobalt doped zinc oxides showed varying degrees of decreased UV and visible light photocatalytic activity, possibly due to metal-mediated charge recombination. The mild chemical dehydration process here allows complex soft botanical structures to be easily utilized for templating materials.

Mesoporous Metal-Organic Frameworks: Synthetic Strategies and Emerging Applications

Metal-organic frameworks (MOFs) have attracted much attention over the past two decades due to their highly promising applications not only in the fields of gas storage, separation, catalysis, drug delivery, and sensors, but also in relatively new fields such as electric, magnetic, and optical materials resulting from their extremely high surface areas, open channels and large pore cavities compared with traditional porous materials like carbon and inorganic zeolites. Particularly, MOFs involving pores within the mesoscopic scale possess unique textural properties, leading to a series of research in the design and applications of mesoporous MOFs. Unlike previous Reviews, apart from focusing on recent advances in the synthetic routes, unique characteristics and applications of mesoporous MOFs, this Review also mentions the derivatives, composites, and hierarchical MOF-based systems that contain mesoporosity, and technical boundaries and challenges brought by the drawbacks of mesoporosity. Moreover, this Review subsequently reveals promising perspectives of how recently discovered approaches to different morphologies of MOFs (not necessarily entirely mesoporous) and their corresponding performances can be extended to minimize the shortcomings of mesoporosity, thus providing a wider and brighter scope of future research into mesoporous MOFs, but not just limited to the finite progress in the target substances alone.

Excited state dynamics and conformations of a Cu(ii)-phthalocyanine-perylenebisimide dyad

We investigate the excited state dynamics and the conformations of a new molecular donor-bridge-acceptor system, a Cu(ii)-phthalocyanine (CuPc) covalently linked via a flexible aliphatic spacer to a perylenebisimide (PBI). We performed time-resolved polarization anisotropy and pump-probe measurements in combination with molecular dynamics simulations. Our data suggest the existence of three conformations of the dyad: two more extended, metastable conformations with centre-of-mass distances >1 nm between the PBI and CuPc units of the dyad, and a highly stable folded structure, in which the PBI and CuPc units are stacked on top of each other with a centre-of-mass distance of 0.4 nm. In the extended conformations the dyad shows emission predominantly from the PBI unit with a very weak contribution from the CuPc unit. In contrast, for the folded conformation the PBI emission of the dyad is strongly quenched due to fast energy transfer from the PBI to the CuPc unit (3 ps) and subsequent intersystem-crossing (300 fs) from the first excited singlet state of CuPc unit into its triplet state. Finally, the CuPc triplet state is deactivated non-radiatively with a time constant of 25 ns.

Facile morphology control of 3D porous CeO2 for CO oxidation

3D porous CeO₂ with various morphologies was successfully synthesized via a facile precipitation using glycine as the soft bio-template. During the synthesis, it was demonstrated that the morphology of CeO₂ depended on the molar ratio of reactants. Furthermore, the catalytic performance towards CO oxidation of the as-synthesized CeO₂ with different morphologies was investigated. CeO₂ with a bowknot shape showed excellent catalytic performance, giving complete CO conversion at 370 °C, due to its properties of much higher oxygen vacancies, loosely packed pore structure and larger specific surface area.

Different morphologies of CeO₂ were obtained via a green and facial method, which realized CO complete conversion at 370 °C.

The highly efficient photocatalytic and light harvesting property of Ag-TiO2 with negative nano-holes structure inspired from cicada wings

The negative replica of biomorphic TiO₂ with nano-holes structure has been effectively fabricated directly from nano-nipple arrays structure of cicada wings by using a simple, low-cost and highly effective sol-gel ultrasonic method. The nano-holes array structure was well maintained after calcination in air at 500 °C. The Ag nanoparticles (10 nm–25 nm) were homogeneously decorated on the surface and to the side wall of nano-holes structure. It was observed that the biomorphic Ag-TiO₂ showed remarkable photocatalytic activity by degradation of methyl blue (MB) under UV-vis light irradiation. The biomorphic Ag-TiO₂ with nano-holes structure showed superior photocatalytic activity compared to the biomorphic TiO₂ and commercial Degussa P25. This high-performance photocatalytic activity of the biomorphic Ag-TiO₂ may be attributed to the nano-holes structure, localized surface plasmon resonance (LSPR) property of the Ag nanoparticles, and enhanced electron-hole separation. Moreover, the biomorphic Ag-TiO₂ showed more absorption capability in the visible wavelength range. This work provides a new insight to design such a structure which may lead to a range of novel applications.

Quantum chemical approaches to [NiFe] hydrogenase

The mechanism by which [NiFe] hydrogenase catalyses the oxidation of molecular hydrogen is a significant yet challenging topic in bioinorganic chemistry. With far-reaching applications in renewable energy and carbon mitigation, significant effort has been invested in the study of these complexes. In particular, computational approaches offer a unique perspective on how this enzyme functions at an electronic and atomistic level. In this article, we discuss state-of-the art quantum chemical methods and how they have helped deepen our comprehension of [NiFe] hydrogenase. We outline the key strategies that can be used to compute the (i) geometry, (ii) electronic structure, (iii) thermodynamics and (iv) kinetic properties associated with the enzymatic activity of [NiFe] hydrogenase and other bioinorganic complexes.

Hierarchically porous materials: synthesis strategies and structure design

This review addresses recent advances in synthesis strategies of hierarchically porous materials and their structural design from micro-, meso- to macro-length scale.