Fabrication of CaFe2O4/TaON Heterojunction Photoanode for Photoelectrochemical Water Oxidation

Solution chemistry quasi-epitaxial growth of atomic CaTiO3 perovskite layers to stabilize and passivate TiO2 photoelectrodes for efficient water splitting

Perovskite oxides with unique crystal structures and high defect tolerance are promising as atomic surface passivation layers for photoelectrodes for efficient and stable water splitting. However, controllably depositing and crystalizing perovskite-type metal oxides at the atomic level remains challenging, as they usually crystalize at higher temperatures than regular metal oxides. Here, we report a mild solution chemistry approach for the quasi-epitaxial growth of an atomic CaTiO3 perovskite layer on rutile TiO2 nanorod arrays. The high-temperature crystallization of CaTiO3 perovskite is overcome by a sequential hydrothermal conversion of the atomic amorphous TiOx layer to CaTiO3 perovskite. The atomic quasi-epitaxial CaTiO3 layer passivated TiO2 nanorod arrays exhibit more efficient interface charge transfer and high photoelectrochemical performance for water splitting. Such a mild solution-based approach for the quasi-epitaxial growth of atomic metal oxide perovskite layers could be a promising strategy for both fabricating atomic perovskite layers and improving their photoelectrochemical properties.

Quantitatively controlled electrophoretic deposition of nanocrystal films from non-aqueous suspensions

This study presents a novel method to correlate the mass and charge transfer kinetics during the electrophoretic deposition of nanocrystal films by using a purpose-built double quartz crystal microbalance combined with simultaneous current-measurement. Our data support a multistep process for film formation: generation of charged nanocrystal flux, charge transfer at the electrode, and polarization of neutral nanocrystals near the electrode surface. The polarized particles are then subject to dielectrophoretic forces that reduce diffusion away from the interface, generating a sufficiently high neutral particle concentration at the interface to form a film. The correlation of mass and charge transfer enables quantification of the nanocrystal charge, the fraction of charged nanocrystals, and the initial sticking coefficient of the particles. These quantities permit calculation of the film thickness, providing a theoretical basis for using concentration and voltage as process parameters to grow films of targeted thicknesses.

Advances in facet-dependent photocatalytic properties of BiOCl catalyst for environmental remediation

Bismuth chloride oxide (BiOCl) is a typical V-VI-VII ternary oxide material, which is one of the widely studied metal oxides due to its unique surface, electronic and photocatalytic properties. However, the broad bandgap and the large number of photogenerated electron-hole pair complexes of BiOCl limit its photocatalytic efficiency. Since the photocatalytic performance of BiOCl is highly dependent on its exposed crystallographic facets, research attention has increasingly focused on the different structures and properties possessed by different crystallographic facets of BiOCl. This article reviews the basic principles of using different crystalline surfaces of BiOCl materials to enhance photocatalytic activity, summarizes the applications of BiOCl single-crystal catalysts and composite catalysts in the environmental field, and provides an outlook on the challenges and new research directions for future development in this emerging frontier area. It is hoped that the crystalline surface-related photocatalysis of BiOCl can be used to provide new guidance for the rational design of novel catalysts for various energy and environment-related applications.

Porous direct Z-scheme heterostructures of S-deficient CoS/CdS hexagonal nanoplates for robust photocatalytic H2 generation

Unique porous S-deficient CoS/CdS hexagonal nanoplates exhibited an outstanding photocatalytic capability for H2 production, due to excellent visible-light response, efficient Z-scheme charge separation, and abundant H2-evolving active sites.

Robust visible-light photocatalytic H2 evolution on 2D RGO/Cd0.15Zn0.85In2S4–Ni2P hierarchitectures

Unique 2D ternary hierarchitectures constructed from reduced graphene oxide nanosheets grown with ultrathin Cd0.15Zn0.85In2S4 nanosheets and Ni2P nanoparticles exhibited an outstanding capability for visible-light photocatalytic H2 production.

Molecular Engineering of Photocathodes based on Polythiophene Organic Semiconductors for Photoelectrochemical Hydrogen Generation

Organic semiconductors provide significant potentials for the construction of photoelectrochemical (PEC) cells for solar hydrogen production because of their highly tunable properties. Herein, on carbon fiber paper (CFP) surface, pyridyl (Py), and 4,4'-bipyridin-1-ium (Py₂⁺) groups were introduced into polythiophene (pTH) semiconductor by electrochemical copolymerization, respectively. After assembly with the Co(dmgBF₂)₂ type catalyst (CoB, dmgBF₂ = difluoroboryldimethylglyoximate), the CoB@Py₂⁺-pTH/CFP photocathode displayed nearly twice the photocurrent enhancement (550 μA cm^-2 at 0.15 V vs reversible hydrogen electrode, RHE) comparing to that generated by the CoB@Py-pTH/CFP photocathode (290 μA cm^-2 at 0.15 V vs RHE) for light-driven H₂ generation under AM 1.5 solar illumination. Investigation of the mechanism revealed that the introduction of the positively charged pyridinium groups could improve the intrinsic Co(dmgBF₂)₂ catalyst activity for the H₂ generation reaction. Meanwhile, the positively charged pyridinium groups serve as p-type dopants to increase the semiconductor bulk charge transfer rate and act as electron transfer mediators to promote the interfacial charge transfer kinetics between the catalyst and the pTH-based organic semiconductor.

Indium Tin-Doped Oxide (ITO) as a High Activity Water Oxidation Photoanode

Photochemical water oxidation was carried out at a mesoporous nanoparticle film composed of indium tin-doped oxide (nanoITO). Annealing nanoITO at temperatures above 250 °C affects both conducting and semiconducting properties. Impressive photoelectrochemical activity was observed at this degenerate n-type semiconductor electrode, outperforming the traditional semiconductor titanium dioxide (TiO₂) under the same conditions. In a 0.1 M HNO₃ solution, the nanoITO electrode sustained photocurrents of 1.0 mA/cm² at an E_applied = 1.5 V vs saturated calomel electrode (SCE) (η = 0.55 V) under a 90 mW/cm² UV illumination (375 nm). This activity is compared to ∼0.3 mA/cm² with a traditional TiO₂ electrode under the same potential and conditions. Evidence for oxygen generation in the photolysis experiments was quantified using the collector-generator method, and >70% photocurrent efficiency for O₂ production was confirmed at this nanoITO photoanode.

Facile construction of 2D g-C3N4 supported nanoflower-like NaBiO3 with direct Z-scheme heterojunctions and insight into its photocatalytic degradation of tetracycline

Photocatalytic oxidation using solar energy is a promising green technology to degrade antibiotic contaminants. Herein, a 2D g-C₃N₄ supported nanoflower-like NaBiO₃ with direct Z-scheme heterojunction was synthesized via a facile hydrothermal approach, and the photocatalytic performance of g-C₃N₄/NaBiO₃ was remarkable better than that of g-C₃N₄ and NaBiO₃ for tetracycline degradation under visible light. Photoinduced electrons accumulated on the conduction band of g-C₃N₄ and holes gathered on the valence band of NaBiO₃, which was more suitable for generating superoxide and hydroxyl radicals. Meanwhile, the built-in electric field between g-C₃N₄ and NaBiO₃ was proved by their different work functions based on DFT calculations, which enhanced the charges separation. The formed radicals were determined by ESR, and their role in the degradation of tetracycline was examined by the active species trapping test. Moreover, the sites attacked by free radicals and degradation pathways for tetracycline were inferred by the results of Gaussian 09 program and HPLC-MS. The effects of water matrix and three other organic contaminants was further studied for actual use evaluation. Importantly, the prepared g-C₃N₄/NaBiO₃ showed stable photodegradation activity for eight cycles. This work not only provides a promising photocatalyst, but also gets insight into the photocatalytic removal of tetracycline.

Covalent SO Bonding Enables Enhanced Photoelectrochemical Performance of Cu2 S/Fe2 O3 Heterojunction for Water Splitting

The severe charge recombination and the sluggish kinetic for oxygen evolution reaction have largely limited the application of hematite (α-Fe₂ O₃ ) for water splitting. Herein, the construction of Cu₂ S/Fe₂ O₃ heterojunction and discover that the formation of covalent SO bonds between Cu₂ S and Fe₂ O₃ can significantly improve the photoelectrochemical performance and stability for water splitting is reported. Compared with bare Fe₂ O₃ , the heterostructure of Cu₂ S/Fe₂ O₃ endows the resulting electrode with enhanced charge separation and transfer, extended range for light absorption, and reduced charge recombination rate. Additionally, due to the photothermal properties of Cu₂ S, the heterostructure exhibits locally a higher temperature under illumination, profitable for increasing the rate of oxygen evolution reaction. Consequently, the photocurrent density of the heterostructure is enhanced by 177% to be 1.19 mA cm^-2 at 1.23 V versus reversible hydrogen electrode. This work may provide guideline for future in the design and fabrication of highly efficient photoelectrodes for various reactions.

Conformal Macroporous Inverse Opal Oxynitride-Based Photoanode for Robust Photoelectrochemical Water Splitting

Direct photoelectrochemical (PEC) water splitting is of prime importance in sustainable energy conversion systems; however, it is a big challenge to simultaneously control light harvesting and charge transport for the improvement of PEC performance. Herein, we report a three-dimensional ordered macroporous (3DOM) CsTaWO_6-xN_x inverse opal array as a promising candidate for the first time. To address the critical challenge, an ultrathin carbon-nitride-based layer-intercalated 3DOM CsTaWO_6-xN_x architecture as a conformal heterojunction photoanode was assembled. This state-of-the-art conformal heterojunction photoanode with carrier-separation efficiency up to 88% achieves a high current density of 4.59 mA cm^-2 at 1.6 V versus a reversible hydrogen electrode (vs RHE) under simulated AM 1.5G illumination, which is approximately 3.4 and 17 times larger than that of pristine CsTaWO_6-xN_x inverse opals and powers photoelectrodes in alkaline media, corresponding to an incident photon-to-current efficiency of 32% at 400 nm and outstanding stability for PEC water splitting. Density functional theory calculations propose that the intimate interface of a conformal photoanode optimizes the charge separation and transfer, thus enhancing the intrinsic water oxidation performance. This work enables us to elucidate the pivotal importance of 3DOM architectures and conformal heterostructures and the promising contributions to excellent PEC water-splitting applications.

A High-Efficiency Hematite Photoanode with Enhanced Bonding Energy Around Fe Atoms

Hematite nanoarrays are important photoanode materials. However, they suffer from serious problems of charge transfer and surface states; in particular, the surface states hinder the increase in photocurrent. A previous strategy to suppress the surface state is the deposition of an Fe-free metal oxide overlayer. Herein, from the viewpoint of atomic bonding energy, it is found that the strength of bonding around Fe atoms in the hematite is the key to suppressing the surface states. By treating the surface of hematite with Se and NaBH₄ , the Fe₂ O₃ transforms to a double-layer nanostructure. In the outer layer, the Fe-O bonding is reinforced and the Fe-Se bonding is even stronger. Therefore, the surface states are inhibited and the increase in the photocurrent density becomes much faster. Besides, the treatment constructs a nanoscale p-n junction to promote the charge transfer. Improvements are achieved in onset potential (0.25 V shift) and in photocurrent density (5.8 times). This work pinpoints the key to suppressing the surface states and preparing a high-efficiency hematite nanoarray, and deepens our understanding of hematite photoanodes.

Solar water oxidation using TaON–BiVO4 photoanodes functionalized with WO3

Enhancements in the water oxidation photocurrent densities at 1.23 V (vs. RHE) by 9.2-fold compared to unmodified TaON–BiVO₄ were achieved with the use of the WO₃/TaON–BiVO₄ photoanodes under visible-light irradiation in this work.

The interplay of Ag and ferromagnetic MgFe2O4 for optimized oxygen-promoted hydrogen evolution via formaldehyde reforming

The interplay of Ag and ferromagnetic MgFe2O4 for optimized oxygen-promoted hydrogen evolution via formaldehyde reforming.

Core-Shell Structured MXene@Carbon Nanodots as Bifunctional Catalysts for Solar-Assisted Water Splitting

The design of nonprecious bifunctional electrocatalysts with high activity and prolonged durability in a wide pH range is essential for the development of the highly efficient, cost-effective, and simplified overall water splitting systems. Here, we report core-shell structured MXene@carbon (MX@C) nanodot hybrids with high bifunctional activity, where N-doped carbon shells are grown in a heteroepitaxial manner strongly interacting with the MXene core. The resulting MX@C nanodot hybrids show enhanced catalytic activity for electrochemical hydrogen evolution reaction (HER) in various pH media from 0 to 14. At pH 14, MX@C achieves the low onset potential of 134 mV at 10 mA/cm² and reduced Tafel slope of 32 mV/dec due to the facilitated charge transfer along the recombination reaction. For the oxygen evolution reaction (OER), MX@C nanodots are incorporated onto the surface of molybdenum-doped bismuth vanadate (Mo:BiVO₄) as a cocatalyst of the photoanode, thereby achieving 1.5 times higher photocurrent density than pristine Mo:BiVO₄ at 1.23 V (vs reversible hydrogen electrode) due to the enhanced light absorption and charge transfer efficiency. The superiority of this hybrid catalyst is demonstrated implementing the solar-assisted overall water splitting cells based on the MX@C cathode and MX@C/Mo:BiVO₄ photoanode. These cells show the enhancement of current density from 0.78 to 1.23 mA/cm² with long-term durability over 8 h. These results are attributed to the facile surface catalytic kinetics of the chemically and electronically coupled MX@C hybrid at the heterointerface for both OER and HER.

A Selective Synthesis of TaON Nanoparticles and Their Comparative Study of Photoelectrochemical Properties

A simplified ammonolysis method for synthesizing single phase TaON nanoparticles is presented and the resulting photoelectrochemical properties are compared and contrasted with as-synthesized Ta2O5 and Ta3N5. The protocol for partial nitridation of Ta2O5 (synthesis of TaON) offers a straightforward simplification over existing methods. Moreover, the present protocol offers extreme reproducibility and enhanced chemical safety. The morphological characterization of the as-synthesized photocatalysts indicate spherical nanoparticles with sizes 30, 40, and 30 nm Ta2O5, TaON, and Ta3N5 with the absorbance onset at ~320 nm, 580 nm, and 630 nm respectively. The photoactivity of the catalysts has been examined for the degradation of a representative cationic dye methylene blue (MB) using xenon light. Subsequent nitridation of Ta2O5 yields significant increment in the conversion (ζ: Ta2O5 < TaON < Ta3N5) mainly attributable to the defect-facilitated adsorption of MB on the catalyst surface and bandgap lowering of catalysts with Ta3N5 showing > 95% ζ for a lower (0.1 g) loading and with a lamp with lower Ultraviolet (UV) content. Improved Photoelectrochemical performance is noted after a series of chronoamperometry (J/t), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) measurements. Finally, stability experiments performed using recovered and treated photocatalyst show no loss of photoactivity, suggesting the photocatalysts can be successfully recycled.

A visible-light-responsive TaON/CdS photocatalytic film with a ZnS passivation layer for highly extraordinary NO2 photodegradation

Recently, TaON has become a promising photoelectrode material in the photocatalytic field owing to its suitable band gap and superior charge carrier transfer ability. In this work, we prepared a TaON/CdS photocatalytic film using a CdS nanoparticle-modified TaON film by the successive ionic layer adsorption and reaction (SILAR) method. For the first time, the ZnS nanoparticles were deposited on the TaON/CdS film using the same method. We found that pure TaON had a nanoporous morphology, thus resulting in high specific surface area and better gas adsorption capacity. Furthermore, the TaON/CdS/ZnS film displayed a highly efficient NO2 photodegradation rate under visible light irradiation owing to its stronger visible light response, photocorrosion preventive capacity, and the high separation efficiency of photo-induced electrons and holes. Interestingly, the promising TaON/CdS/ZnS film also possessed remarkable recyclability for NO2 degradation. Therefore, we suggest that the TaON/CdS/ZnS photocatalytic film might be used for the photocatalytic degradation of other pollutants or in other applications. We also put forward the feasible NO2 photocatalytic degradation mechanism for the TaON/CdS/ZnS film. From the schematic diagram, we could further obtain the photo-generated carrier transport process and NO2 photodegradation principle in detail over the ternary photocatalytic film. Moreover, the trapping experiment demonstrates that ·O2 - and h+ all play significant roles in NO2 degradation under visible light irradiation.

Highly active deficient ternary sulfide photoanode for photoelectrochemical water splitting

The exploration of photoanode materials with high efficiency and stability is the eternal pursuit for the realization of practically solar-driven photoelectrochemical (PEC) water splitting. Here we develop a deficient ternary metal sulfide (CdIn2S4) photoanode, and its PEC performance is significantly enhanced by introducing surface sulfur vacancies, achieving a photocurrent density of 5.73 mA cm-2 at 1.23 V vs. RHE and 1 Sun with an applied bias photon-to-current efficiency of 2.49% at 0.477 V vs. RHE. The experimental characterizations and theoretical calculations highlight the enhanced effect of surface sulfur vacancies on the interfacial charge separation and transfer kinetics, which also demonstrate the restrained surface states distribution and the transformation of active sites after introducing surface sulfur vacancies. This work may inspire more excellent work on developing sulfide-based photoanodes.

A TiO2/Nb2O5·nH2O heterojunction catalyst for conversion of glucose into 5-hydroxymethylfurfural in water

A series of water-tolerant Lewis acidic TiO₂/Nb₂O₅·nH₂O heterojunction catalysts with different Ti : Nb ratios have been prepared and investigated in the conversion of glucose into HMF in water.

Accelerated charge transfer of Cd0.5Zn0.5S@ZnS core–shell nano-spheres via decoration of Ni2P and g-C3N4 toward efficient visible-light-driven H2 production

Unique Cd_0.5Zn_0.5S@ZnS-Ni₂P/g-C₃N₄ hybrid nano-spheres demonstrate enhanced photostability, improved light-harvesting and facilitated charge separation toward efficient H₂ evolution from visible-light-driven water-splitting.

Photocatalytic Oxygen Evolution from Water Splitting

Photocatalytic water splitting has attracted a lot of attention in recent years, and O2 evolution is the decisive step owing to the complex four-electrons reaction process. Though many studies have been conducted, it is necessary to systematically summarize and introduce the research on photocatalytic O2 evolution, and thus a systematic review is needed. First, the corresponding principles about O2 evolution and some urgently encountered issues based on the fundamentals of photocatalytic water splitting are introduced. Then, several types of classical water oxidation photocatalysts, including TiO2, BiVO4, WO3, α-Fe2O3, and some newly developed ones, such as Sillén-Aurivillius perovskites, porphyrins, metal-organic frameworks, etc., are highlighted in detail, in terms of their crystal structures, synthetic approaches, and morphologies. Third, diverse strategies for O2 evolution activity improvement via enhancing photoabsorption and charge separation are presented, including the cocatalysts loading, heterojunction construction, doping and vacancy formation, and other strategies. Finally, the key challenges and future prospects with regard to photocatalytic O2 evolution are proposed. The purpose of this review is to provide a timely summary and guideline for the future research works for O2 evolution.

Designed synthesis of unique ZnS@CdS@Cd0.5Zn0.5S-MoS2 hollow nanospheres for efficient visible-light-driven H2 evolution

Unique ZnS@CdS@Cd_0.5Zn_0.5S-MoS₂ hollow nanospheres with abundant active sites and enhanced light-harvesting and charge separation demonstrate efficient H₂ evolution from visible-light-driven water-splitting.

Tri-functional molecular relay to fabricate size-controlled CoOx nanoparticles and WO3 photoanode for an efficient photoelectrochemical water oxidation

Heterojunction and element doping to couple light-harvesting semiconductors with catalytic materials have been widely employed for photoelectrochemical (PEC) water splitting.

Interfacial Coupling Effect on Electron Transport in Hierarchical TaON/Au/ZnCo-LDH Photoanode with Enhanced Photoelectrochemical Water Oxidation

Rational design and construction of interface heterostructures, which can simultaneously accelerate the photoinduced carrier separation and enhance the surface water oxidation kinetics, is of great necessity for photoelectrochemical (PEC) water oxidation. Herein, we report a new strategy for boosting the PEC water oxidation by introducing Schottky junction and semiconductor/water oxidation cocatalysts (SC/WOCs) junction into the TaON photocatalyst. Compared with pristine TaON photoanode, the hierarchical TaON/Au/ZnCo-LDH (LDH = layered double hydroxide) photoanode reveals a cathodic shift of 156 mV for the onset potential and 17.3-fold photocurrent density enhancement at 1.23 V vs RHE, as well as improved long-term stability. Diagnostic efficiencies of the TaON/Au/ZnCo-LDH photoanode demonstrate that the enhanced PEC performance is not dominated by surface electrochemical water oxidation kinetics but largely contributed by the improved charge separation and transfer, indicative of synergistic effects of Au and ZnCo-LDH. Theoretical calculations further reveal that the midgap states introduced by Au and ZnCo-LDH in TaON electronic structures bring about photoexcited electrons concentrated on TaON, while holes accumulated on ZnCo-LDH to achieve efficiently spatial charge separation, which is responsible for the boosted PEC water oxidation performance. The present work highlights the importance and elucidates the mechanism of interface heterojunction in PEC water oxidation, which can provide an efficient approach to design and fabricate a new structural photoanode.

Unique 1D Cd1- x Znx S@O-MoS2 /NiOx Nanohybrids: Highly Efficient Visible-Light-Driven Photocatalytic Hydrogen Evolution via Integrated Structural Regulation

Development of noble-metal-free photocatalysts for highly efficient sunlight-driven water splitting is of great interest. Nevertheless, for the photocatalytic H₂ evolution reaction (HER), the integrated regulation study on morphology, electronic band structures, and surface active sites of catalyst is still minimal up to now. Herein, well-defined 1D Cd_{1- x} Zn_x S@O-MoS₂ /NiO_x hybrid nanostructures with enhanced activity and stability for photocatalytic HER are prepared. Interestingly, the band alignments, exposure of active sites, and interfacial charge separation of Cd_{1- x} Zn_x S@O-MoS₂ /NiO_x are optimized by tuning the Zn-doping content as well as the growth of defect-rich O-MoS₂ layer and NiO_x nanoparticles, which endow the hybrids with excellent HER performances. Specifically, the visible-light-driven (>420 nm) HER activity of Cd_{1- x} Zn_x S@O-MoS₂ /NiO_x with 15% Zn-doping and 0.2 wt% O-MoS₂ (CZ_0.15 S-0.2M-NiO_x ) in lactic acid solution (66.08 mmol h^-1 g^-1 ) is about 25 times that of Pt loaded CZ_0.15 S, which is further increased to 223.17 mmol h^-1 g^-1 when using Na₂ S/Na₂ SO₃ as the sacrificial agent. Meanwhile, in Na₂ S/Na₂ SO₃ solution, the CZ_0.15 S-0.2M-NiO_x sample demonstrates an apparent quantum yield of 64.1% at 420 nm and a good stability for HER under long-time illumination. The results presented in this work can be valuable inspirations for the exploitation of advanced materials for energy-related applications.

Quaternary Core-Shell Oxynitride Nanowire Photoanode Containing a Hole-Extraction Gradient for Photoelectrochemical Water Oxidation

A nanowire photoanode SrTaO₂N, a semiconductor suitable for overall water-splitting with a band gap of 2.3 eV, was coated with functional overlayers to yield a core-shell structure while maintaining its one-dimensional morphology. The nanowires were grown hydrothermally on tantalum, and the perovskite-related oxynitride structure was obtained by nitridation. Three functional overlayers have been deposited on the nanowires to enhance the efficiency of photoelectrochemical (PEC) water oxidation. The deposition of TiO _x protects the oxynitride from photocorrosion and suppresses charge-carrier recombination at the surface. Ni(OH) _x acts a hole-storage layer and decreases the dark-current contribution. This leads to a significantly improved extraction of photogenerated holes to the electrode-electrolyte surface. The photocurrents can be increased by the deposition of a cobalt phosphate (CoP_i) layer as a cocatalyst. The heterojunction nanowire photoanode generates a current density of 0.27 mA cm^-2 at 1.23 V vs the reversible hydrogen electrode (RHE) under simulated sunlight (AM 1.5G). Simultaneously, the dark-current contribution, a common problem for oxynitride photoanodes grown on metallic substrates, is almost completely minimized. This is the first report of a quaternary oxynitride nanowire photoanode in core-shell geometry containing functional overlayers for synergetic hole extraction and an electrocatalyst.

Pt nanoparticles decorated heterostructured g-C3N4/Bi2MoO6 microplates with highly enhanced photocatalytic activities under visible light

Exploring an efficient and photostable heterostructured photocatalyst is a pivotal scientific topic for worldwide energy and environmental concerns. Herein, we reported that Pt decorated g-C₃N₄/Bi₂MoO₆ heterostructured composites with enhanced photocatalytic performance under visible light were simply synthesized by one-step hydrothermal method for methylene blue (MB) dye degradation. Results revealed that the synthetic Pt decorated g-C₃N₄/Bi₂MoO₆ composites with Bi₂MoO₆ contents of 20 wt.% (Pt@CN/20%BMO) presented the highest photocatalytic activity, exhibiting 7 and 18 times higher reactivity than the pure g-C₃N₄ and Bi₂MoO₆, respectively. Structural analyses showed that Bi₂MoO₆ microplates were anchored on the wrinkled flower-like g-C₃N₄ matrix with Pt decoration, leading to a large expansion of specific surface area from 10.79 m²/g for pure Bi₂MoO₆ to 46.09 m²/g for Pt@CN/20%BMO. In addition, the Pt@CN/20%BMO composites exhibited an improved absorption ability in the visible light region, presenting a promoted photocatalytic MB degradation. Quenching experiments were also conducted to provide solid evidences for the production of hydroxyl radicals (^•OH), electrons (e⁻), holes (h⁺) and superoxide radicals (^•O²⁻) during dye degradation. The findings in this critical work provide insights into the synthesis of heterostructured photocatalysts with the optimization of band gaps, light response and photocatalytic performance in wastewater remediation.

Heterostructure of 1D Ta3 N5 Nanorod/BaTaO2 N Nanoparticle Fabricated by a One-Step Ammonia Thermal Route for Remarkably Promoted Solar Hydrogen Production

Heterostructures are widely fabricated for promotion of photogenerated charge separation and solar cell/fuel production. (Oxy)nitrides are extremely promising for solar energy conversion, but the fabrication of heterostructures based on nitrogen-containing semiconductors is still challenging. Here, a simple ammonia thermal synthesis of a heterostructure (denoted as Ta₃ N₅ /BTON) composed of 1D Ta₃ N₅ nanorods and BaTaO₂ N (BTON) nanoparticles (0D), which is demonstrated to result in a remarkable increase in photogenerated charge separation and solar hydrogen production from water, is introduced. As analyzed and discussed, the Ta₃ N₅ /BTON heterostructure is type II and tends to create intimate interfaces between the 1D nanorods and 0D nanoparticles. The 1D Ta₃ N₅ nanorods are demonstrated to transfer electrons along the rod orientation direction. Furthermore, the intimate interfaces of the heterostructure are believed to originate from the similar Ta-based octahedron units of Ta₃ N₅ and BTON. All of the above features are expected to integrally endow increased photoinduced charge separation and one order of magnitude higher solar overall water splitting activity with respect to counterpart systems. These results may open a new avenue to fabricate heterostructures on the basis of nitrogen-containing semiconductors that is extremely promising for solar energy conversion.

Understanding and improving photoelectrochemical performance of Bi2O3/Bi2S3 composite

The simple and fast ultrasonic-assisted synthesis of high-performance, low-interfacial-resistance Bi₂O₃/Bi₂S₃ composite semiconductors is demonstrated.

Fabrication of a Au-loaded CaFe2O4/CoAl LDH p–n junction based architecture with stoichiometric H2 & O2 generation and Cr(vi) reduction under visible light

Visible-light-efficient Au-loaded CaFe₂O₄/CoAl LDH p–n junction for H₂ & O₂ generation and Cr(vi) reduction.

Single-crystal silicon-based electrodes for unbiased solar water splitting: current status and prospects

This review describes recent developments of single-crystal silicon (Si) as the photoelectrode material for solar water splitting, including the promising strategies to obtain highly efficient and stable single-crystal Si-based photoelectrodes for hydrogen evolution and water oxidation, as well as the future development of spontaneous solar water splitting with single-crystal Si-based tandem cells.