Photoelectrochemical Oxygen Evolution Research Articles

Rational synthesis of highly efficient dual–Z–scheme InVO4/FeVO4/Ex–CQDs–g–C3N4 heterojunction for photo(electro)chemical water splitting and pollutant removal applications

BackgroundThe ever–growing concern for environmental pollution and the need for clean energy sources have driven research toward sustainable technologies. Semiconductor photocatalysis has emerged as a promising approach for both environmental remediation and clean energy generation due to its efficiency and environment–friendly nature. This work focuses on developing a novel photocatalyst capable of addressing two crucial environmental challenges: Cr(VI) removal and water splitting for clean hydrogen production. MethodsThis study presents the development of a dual–Z–scheme heterojunction photo(electro)catalyst based on a combination of metal vanadates (FeVO4 and InVO4) and ultrasound–exfoliated carbon–rich graphitic carbon nitride (Ex–C–g–CN), denoted as IVO/FVO/Ex–C–g–CN. The synthesized nanocomposite was thoroughly characterized using various spectroscopic and microscopic techniques (such as XRD, XPS, UV–DRS, FESEM, EDX, and PL) to understand its material properties and structure. These techniques are crucial for elucidating the relationship between the composition of the material and its photocatalytic performance. Significant findingsThe key innovation of this work lies in the design of the dual–Z–scheme heterojunction within the IVO/FVO/Ex–C–g–CN photo(electro)catalyst. This design fosters efficient separation of photogenerated charges, a critical factor for enhancing photocatalytic activity. The effectiveness of this approach is evident in the achieved removal efficiency of 97.17 % for 100 ppm Cr(VI) within just 60 min of visible light irradiation. This demonstrates the superior ability of the developed photocatalyst to address chromium contamination. Furthermore, the photocatalyst exhibits a remarkable photocurrent of 3.16 mA and a low onset potential of 112 mV for the photoelectrochemical oxygen evolution (OER) reaction. These findings highlight the potential of this material for solar–driven water splitting, a clean and sustainable method for hydrogen production. Additionally, the IVO/FVO/Ex–C–g–CN composite demonstrates excellent recyclability, maintaining high Cr(VI) removal efficiency over multiple cycles, indicating its reusability and cost-effectiveness. Overall, the exceptional photo(electro)catalytic performance of the IVO/FVO/Ex–C–g–CN dual–Z–scheme heterojunction positions it as a promising candidate for tackling environmental pollution and generating clean energy.

Origin of the Improved Photoelectrochemical and Photocatalytic Activity in a ZnO-TiO2 Nanohybrid Revealed by Experimental and Density Functional Theory Studies.

Heterojunctions of metal oxides have attracted a great deal of attention as photo (electro) catalysts owing to their excellent photoactivity. While multiple fundamental studies have been dedicated to heteroaggregation, self-assembly of oppositely charged particles to obtain heterojunctions for energy applications has been underexplored. Herein, we report the synthesis of ZnO-TiO2 heterojunctions using the electrostatic self-assembly approach. The synthesized ZnO-TiO2 heterojunctions were characterized by using multiple experimental techniques. Density functional theory calculations were conducted to establish the heterojunction formation mechanism and electronic properties. The ZnO-TiO2 nanohybrid was tested for the photodegradation of rhodamine B dye and water splitting applications. The photocatalytic performance of the ZnO-TiO2 nanohybrid is 3.5 times higher than that of bare ZnO. In addition, the heterostructure exhibited an excellent photocurrent density of 2.4 mA cm-2 at a low onset potential during photoelectrochemical oxygen evolution. The performance improvements are attributed to the formation of the type II heterojunction between ZnO and TiO2, which suppresses carrier recombination and enhances carrier transport, boosting the catalytic activity.

A kinetics-based approach to the steady-state and impedance response of photoelectrodes

A kinetics-based analytical model is developed to describe the steady-state and impedance response of photoelectrodes in the case where charge carrier build-up modifies the potential distribution across the semiconductor-electrolyte junction. The predictions of the steady-state model are compared with numerical calculations. It is shown that carrier build up should accelerate interfacial hole transfer by increasing the potential drop across the Helmholtz layer. This effect may explain observations of higher reaction orders with respect to hole concentration during photoelectrochemical oxygen evolution. The analytical model is extended to photoelectrochemical impedance spectroscopy (PEIS). The calculations indicate that interpretation of PEIS measurements becomes more complicated if high illumination intensities are used. The modeling of the analytically calculated PEIS response using equivalent circuits is discussed with the aim of understanding the physical significance of the resistive and capacitive elements.

Molecular Engineering of Perylene Diimide Polymers with a Robust Built-in Electric Field for Enhanced Solar-Driven Water Splitting.

The built-in electric field of the polymer semiconductors could be regulated by the dipole moment of its building blocks, thereby promoting the separation of photogenerated carriers and achieving efficient solar-driven water splitting. Herein, three perylene diimide (PDI) polymers, namely oPDI, mPDI and pPDI, are synthesized with different phenylenediamine linkers. Notably, the energy level structure, light-harvesting efficiency, and photogenerated carrier separation and migration of polymers are regulated by the orientation of PDI unit. Among them, oPDI enables a large dipole moment and robust built-in electric field, resulting in enhanced solar-driven water splitting performance. Under simulated sunlight irradiation, oPDI exhibits the highest photocurrent of 115.1 μA cm-2 for photoelectrochemical oxygen evolution, which is 11.5 times that of mPDI, 26.8 times that of pPDI and 104.6 times that of its counterparts PDI monomer at the same conditions. This work provides a strategy for designing polymers by regulating the orientation of structural units to construct efficient solar energy conversion systems.

Molecular Engineering of Perylene Diimide Polymers with a Robust Built‐in Electric Field for Enhanced Solar‐Driven Water Splitting

AbstractThe built‐in electric field of the polymer semiconductors could be regulated by the dipole moment of its building blocks, thereby promoting the separation of photogenerated carriers and achieving efficient solar‐driven water splitting. Herein, three perylene diimide (PDI) polymers, namely oPDI, mPDI and pPDI, are synthesized with different phenylenediamine linkers. Notably, the energy level structure, light‐harvesting efficiency, and photogenerated carrier separation and migration of polymers are regulated by the orientation of PDI unit. Among them, oPDI enables a large dipole moment and robust built‐in electric field, resulting in enhanced solar‐driven water splitting performance. Under simulated sunlight irradiation, oPDI exhibits the highest photocurrent of 115.1 μA cm−2 for photoelectrochemical oxygen evolution, which is 11.5 times that of mPDI, 26.8 times that of pPDI and 104.6 times that of its counterparts PDI monomer at the same conditions. This work provides a strategy for designing polymers by regulating the orientation of structural units to construct efficient solar energy conversion systems.

Zirconium (Oxy)Nitrides for (Photo)Electrochemical Applications

Transition metal (TM) nitrides are an emerging class of (photo)electrocatalytic materials that have recently received growing research interest.1,2 In general, nitrogen-poor TM nitrides are usually refractory materials with metallic character while nitrogen-rich nitrides often possess semiconducting character.3 Hence, while the former are potential electrocatalyst candidates, the latter may qualify as photoelectrode absorber materials. For example, ZrN has recently been proposed as an electrocatalyst for both the electrochemical nitrogen4 and oxygen5 reduction reactions (ORR and NRR), while Zr3N4 and also Zr2N2O have been suggested as potential photoanode materials in photoelectrochemical water oxidation.2 In this contribution, we test these hypotheses regarding the (photo)electrochemical characteristics of Zr-based (oxy)nitrides by experiment. To this end, we investigate reactively sputtered thin films for the electrochemical NRR/ORR and the photoelectrochemical oxygen evolution reaction (OER). Previous experiments on Ta-based nitrides have shown that addition of oxygen during the reactive sputter process is necessary to access higher metal oxidation states.6 As we introduce controlled amounts of oxygen at otherwise fixed deposition conditions, we observe a transition from metallic ZrN to a disordered nitrogen-rich ZrxNy to a crystalline bixbyite-type Zr2N2O to nitrogen-doped cubic ZrO2. Crystalline Zr3N4 was not accessible under the used experimental conditions. In our experiments, we observe a lack of electrocatalytic activity for ZrN in NRR and ORR and instabilities of the disordered nitrogen-rich ZrxNy in the photoelectrochemical OER. Introducing more oxygen into the structure, however, leads to a more stable crystalline structure (Zr2N2O), the opening of a band gap in the visible range, and the emergence of photoelectrochemical activity for oxidation reactions. Based on chopped linear sweep voltammetry measurements, we show that Zr2N2O films are photoactive for the OER in alkaline electrolyte with low onset potentials, indicating an overall favorable band alignment of the material with respect to the water oxidation and reduction potentials. While the observed photocurrents are still about one order of magnitude lower than for the benchmark oxynitride photoanode TaON, further material optimization could potentially close this gap and provide a materials system functioning as sustainable photoanode.References 1 W. Sun, C.J. Bartel, E. Arca, S.R. Bauers, B. Matthews, B. Orvañanos, B.R. Chen, M.F. Toney, L.T. Schelhas, W. Tumas, J. Tate, A. Zakutayev, S. Lany, A.M. Holder, and G. Ceder, Nat. Mater. 18, 732 (2019). 2 Y. Wu, P. Lazic, G. Hautier, K. Persson, and G. Ceder, Energy Environ. Sci. 6, 157 (2013). 3 A. Salamat, A.L. Hector, P. Kroll, and P.F. McMillan, Coord. Chem. Rev. 257, 2063 (2013). 4 Y. Abghoui, A.L. Garden, J.G. Howalt, T. Vegge, and E. Skúlason, ACS Catal. 6, 635 (2016). 5 Y. Yuan, J. Wang, S. Adimi, H. Shen, T. Thomas, R. Ma, J.P. Attfield, and M. Yang, Nat. Mater. 19, (2019). 6 C.M. Jiang, L.I. Wagner, M.K. Horton, J. Eichhorn, T. Rieth, V.F. Kunzelmann, M. Kraut, Y. Li, K.A. Persson, and I.D. Sharp, Mater. Horizons 8, 1744 (2021).

Oxygen Bridge Formed by Doping Nonmetal Atoms into Cationic Vacancies To Enhance the Photoelectrochemical Oxygen Evolution Reaction.

To enhance photoelectrochemical (PEC) water splitting for renewable energy conversion, the conventional strategy is doping nonmetals into anionic vacancies. Compared to anionic vacancies, cationic vacancies are theoretically more effective and reliable for anchoring nonmetals owing to their larger radii and unique advantages. The current research mainly focuses on anionic vacancies, while there are few studies on cationic vacancies due to high formation energy and challenging characterizations by convenient techniques. To overcome the current limitations, nonmetallic S and P atoms are successfully doped into cationic vacancies on the TiO2 surface for tuning local electronic structures. In contrast to the traditional strategy of reducing the bandgaps, nonmetallic atom doping into cationic vacancies facilitates efficient electronic regulation for PEC enhancement without changing the bandgap. The enhanced performance is attributed to the formation of an oxygen bridge, which can accumulate electrons from surrounding S/P atoms. Significantly, the electron-enriched oxygen bridge efficiently transfers electrons to activate reaction site Ti, which can promote the oxygen evolution reaction performance. Density functional theory calculations reveal that the decrease of reaction energy barriers and the optimization of local electron distribution are conducive to electronic transmission. This would provide a high-efficiency electronic tuning strategy for improving PEC performance.

Architecting the High‐Entropy Oxides on 2D MXene Nanosheets by Rapid Microwave‐Heating Strategy with Robust Photoelectrochemical Oxygen Evolution Performance (Small 27/2023)

Architecting the High‐Entropy Oxides on 2D MXene Nanosheets by Rapid Microwave‐Heating Strategy with Robust Photoelectrochemical Oxygen Evolution Performance (Small 27/2023)

Solar Driven 15.7% Hydrogen Conversion by Harmony of Light Harvesting, Electron Transporting Bridge, and S‐Defection in a Self‐Assembled Microscale CuS/rGO/CP Photoanode

CuS is an encouraging photoelectrode candidate that meets the essential requirements for efficient solar‐to‐hydrogen production, but it has not been thoroughly studied. A CuS light absorber layer is grown by the self‐assembly of copper and sulfur precursors on a carbon paper (CP) electrode. Simultaneously, rGO is introduced as a buffer layer to control the optical and electrical properties of the absorber. The well‐ordered microstructural arrangement suppresses the recombination loss of electrons and holes owing to enhanced charge‐carrier generation, separation, and transport. The potential reaching 10 mA cm−2 in 1.0 m KOH solution is significantly lowered to 0.87 V, and the photocurrent density at 1.23 V is 94.7 mA cm−2. The computational result reveals that the potential‐determining step is sensitive to O* stability; the lower stability of O* in the thin layer of CuS/rGO decreases the free‐energy gap between the initial and final states of the potential‐determining step, resulting in a lowering of the onset potential. The faradaic efficiency for the photoelectrochemical oxygen evolution reaction in the optimized 2CuS/1rGO/CP photoanode is 98.60%, and the applied bias photon‐to‐current and the solar‐to‐hydrogen efficiencies are 11.2% and 15.7%, respectively, and its ultra‐high performance is maintained for 250 h. These record‐breaking achievement indices may be a trigger for establishing a green hydrogen economy.

Ti-doped Fe2O3 photoanodes on three-dimensional titanium microfiber felt substrate for photoelectrochemical oxygen evolution reaction

The macroporous structure of conductive substrates with large surface areas is crucial for fabricating semiconductor electrodes that offer better photoelectrochemical (PEC) performance in the water-splitting reaction. In this study, three-dimensional (3D) titanium microfiber felt (Ti felt) was used as a conductive substrate to prepare a Ti-doped Fe2O3 photoanode via a hydrothermal method with a two-step annealing treatment in air and argon atmospheres. Compared to conventional two-dimensional (2D) substrates, such as fluorine-doped tin oxide (FTO)-coated glass and Ti sheets, the loading amount of Fe2O3 on Ti felt was 2–5 times higher for a similar substrate geometric area. The thickness of Fe2O3 on the Ti felt (∼0.6 µm) was less than that on the 2D substrates. Ti-doped Fe2O3 on Ti felt (Ti-felt/Ti-Fe2O3) exhibits a higher photocurrent density than FTO/Ti-Fe2O3 and Ti-sheet/Ti-Fe2O3. Mott–Schottky analysis shows that the donor density of Ti-felt/Ti-Fe2O3 (8.58 × 1021 cm−3) was more than 10 times higher than that of FTO/Ti-Fe2O3 and Ti-sheet/Ti-Fe2O3. Analyses of the incident photon-to-current conversion efficiency (IPCE) and Faradaic efficiency indicated that Ti-felt/Ti-Fe2O3 showed higher PEC activity for the oxygen evolution reaction (OER) than FTO/Ti-Fe2O3. The enhanced PEC activity is ascribed to the higher donor density and moderate thickness of the Ti-doped Fe2O3 layer, which contribute to a short electron transport distance. Furthermore, the high loading of Fe2O3 on the Ti-felt substrate increased the photoabsorption in the UV and visible light regions and the photocurrent response at wavelengths near the band edge, even at low light intensities. This study provides new insights for preparing hematite photoanodes with higher PEC activity for the OER using a 3D porous substrate, rather than conventional 2D substrates.

Facile fabrication of P-type hematite thin film and application for enhanced photoelectrochemical oxygen evolution reaction efficiency

Facile fabrication of P-type hematite thin film and application for enhanced photoelectrochemical oxygen evolution reaction efficiency

Architecting the High-Entropy Oxides on 2D MXene Nanosheets by Rapid Microwave-Heating Strategy with Robust Photoelectrochemical Oxygen Evolution Performance.

High-entropy oxides (HEO) have recently concerned interest as the most promising electrocatalytic materials for oxygen evolution reactions (OER). In this work, a new strategy to the synthesis of HEO nanostructures on Ti3 C2 Tx MXene via rapid microwave heating and subsequent calcination at a low temperature is reported. Furthermore, the influence of HEO loading on Ti3 C2 Tx MXene is investigated toward OER performance with and without visible-light illumination in an alkaline medium. The obtained HEO/Ti3 C2 Tx -0.5 hybrid exhibited an outstanding photoelectrochemical OER ability with a low overpotential of 331mV at 10mA cm-2 and a small Tafel slope of 71mV dec-1 , which exceeded that of a commercial IrO2 catalyst (340mV at 10mA cm-2 ). In particular, the fabricated water electrolyzer with the HEO/Ti3 C2 Tx -0.5 hybrid as anode required a less potential of 1.62V at 10mA cm-2 under visible-light illumination. Owing to the strong synergistic interaction between the HEO and Ti3 C2 Tx MXene, the HEO/Ti3 C2 Tx hybrid has a great electrochemical surface area, many metal active sites, high conductivity, and fast reaction kinetics, resulting in an excellent OER performance. This study offers an efficient strategy for synthesizing HEO-based materials with high OER performance to produce high-value hydrogen fuel.

Highly enhanced photocatalytic activity of nanotubular Fe2O3/Fe2WO6 nanocomposite film formed by anodizing FeW alloy

This study demonstrates the highly enhanced photocatalytic activity of Fe2O3 nanotubes by making a heterojunction with Fe2WO6 and doping of W6+ ions into the α-Fe2O3 phase for water splitting and decomposition of an organic pollutant. Both nanotubular and compact Fe2O3/Fe2WO6 films are formed by anodizing the magnetron-sputtered Fe-9 at% W alloy in fluoride-containing ethylene glycol electrolyte and subsequent annealing at 450 °C. Their photocatalytic activities are compared with W-free nanoporous Fe2O3 film formed on high-purity Fe. The nanotubular Fe2O3/Fe2WO6 film exhibits a markedly enhanced photoelectrochemical oxygen evolution reaction and photocatalytic degradation of methylene blue compared with the nanoporous W-free Fe2O3 film. Because of the larger surface area, the nanotubular Fe2O3/Fe2WO6 film reveals further increased activity than the compact Fe2O3/Fe2WO6 film. The STEM study discloses the dispersion of Fe2WO6 nanoparticles in the α-Fe2O3 phase after annealing at 450 °C, and XRD analysis shows the possible doping of W species into α-Fe2O3. The formation of the W-doped α-Fe2O3/Fe2WO6 heterojunction likely promotes the separation of photogenerated electron-hole pairs, enhancing photocatalytic activity. Hence, the nanotubular Fe2O3/Fe2WO6 film is a possible candidate for visible-light-driven photocatalysts.

Enhancing long-term stability of bio-photoelectrochemical cell by defect engineering of a WO3-x photoanode

Bio-photoelectrochemical cells (BPECs) can further expand the use of conventional biofuel cells for renewable energy, but the poor stability of the photoelectrode still hinders their practical application. Herein, a BPEC capable of long-term operating in a fuel-free model is fabricated by WO3-x photoanode with oxygen vacancy (Ov) and bilirubin oxidase catalyzed biocathode. The construction of Ov on the WO3 surface significantly suppresses the dissolution of W species into the electrolyte, and improves the charge separation efficiency and the reaction kinetics during the photoelectrochemical oxygen evolution process, thus enhancing the stability and power output performance of the BPEC. As a result, the assembled BPEC can output an open circuit voltage of 0.81 V and deliver a maximum output power of up to 283 μW cm−2. Impressively, the BPECs maintain 97% of their original power after 36000 s of consecutive discharge under an enclosed environment. This fuel-free BPEC based on a robust WO3-x photoanode shows excellent promise for accurate application.

Facile Synthesis of PdO.TiO2 Nanocomposite for Photoelectrochemical Oxygen Evolution Reaction

The rapid depletion of fossil fuels and environmental pollution has motivated scientists to cultivate renewable and green energy sources. The hydrogen economy is an emerging replacement for fossil fuels, and photocatalytic water splitting is a suitable strategy to produce clean hydrogen fuel. Herein, the photocatalyst (PdO.TiO2) is introduced as an accelerated photoelectrochemical oxygen evolution reaction (OER). The catalyst showed significant improvement in the current density magnitude from 0.89 (dark) to 4.27 mA/cm2 (light) during OER at 0.5 V applied potential. The as-synthesized material exhibits a Tafel slope of 170 mVdec-1 and efficiency of 0.25% at 0.93 V. The overall outcomes associated with the photocatalytic activity of PdO.TiO2 demonstrated that the catalyst is highly efficient, thereby encouraging researchers to explore more related catalysts for promoting facile OER.

An effective strategy for promoting charge separation by integrating heterojunctions and multiple homojunctions in TiO2 nanorods to enhance photoelectrochemical oxygen evolution.

It is important to achieve high photoelectrochemical (PEC) oxygen evolution performance in titanium oxide (TiO2) via the separation and transportation of photogenerated carriers. Herein, three-dimensional (3D) TiO2 nanorod arrays growing on flexible carbon cloth (CC) were decorated with graphitic carbon nitride (g-C3N4) to yield a 3D g-C3N4/TiO2/CC heterojunction composite (TCN). The photocurrent density of TCN is 10.6 times that of the bare TiO2 nanorod arrays, which can be attributed to the promoted separation and transportation of photogenerated carriers by the heterojunction. Then, a simple rapid cooling and heating (RCH) treatment was creatively introduced to form a gradient Ti3+ self-doping TiO2 multiple homojunction (GTSD-TiO2) in the bulk during the hydrothermal growth of the TiO2 nanorod array. This can further facilitate the separation and transportation of carriers in the bulk owing to the formation of a built-in electric field. The GTSD-TiO2 was decorated with g-C3N4 to form a core-shell heterojunction composite (GTSD-TCN). Notably, the photocurrent density of the GTSD-TCN core-shell heterojunction reached 1.23mAcm-2 at 1.23V (vs reversible hydrogen electrode (RHE)) under air mass (AM) 1.5 G illumination without the use of hole scavengers or cocatalysts; this was twice the photocurrent density of the TCN heterojunction (0.64mAcm-2) and is one of the best values obtained from the previously reported TiO2 and g-C3N4 heterojunction. This performance may be ascribed to the enhanced charge separation and transportation efficiency of the heterojunction after the RCH treatment; the efficiency rises from 51% (TCN) to 71% (GTSD-TCN). We believe that the RCH treatment is a highly promising method towards fabricating unique multiple homojunctions by gradient self-doping. This simple and novel design provides a new route for the preparation of high-performance PEC photoelectrodes.

High-temperature stabilized defect pyrochlore Bi2−xFexWO6 nanostructures and their effects on photocatalytic water remediation and photo-electrochemical oxygen evolution kinetics

Optimal Fe-substituted Bi2WO6 nanostructures, stabilized at higher temperatures, exhibited better band hybridization leading to improved photocatalytic and photoelectrochemical performance.

Physicochemical insights into semiconductor properties of a semitransparent tantalum nitride photoanode for solar water splitting.

The self-conductivity of tantalum nitride (Ta3N5) thin film-based semitransparent photoanodes was found to promote the current originating from the photoelectrochemical oxygen evolution reaction (PEC OER) without a conducting substrate. With surface modification by the NiFeOx-electrocatalyst, an optimized Ta3N5 thin film fabricated directly on a transparent insulating quartz substrate generated a photocurrent density of ∼5.9 ± 0.1 mA cm-2 at 1.23 V vs. the reversible hydrogen electrode under simulated AM 1.5G solar illumination. The correlation between the PEC OER performance of NiFeOx-modified Ta3N5 photoanodes and the electrical properties of Ta3N5 thin films was investigated based on the Hall effect measurements. By changing the nitridation conditions, these properties can be tuned so that the higher the Hall mobility (0.2 to 1.7 cm2 V-1 s-1) and the lower the carrier concentration (1020 to 1019 cm-3). The surface chemical states of Ta3N5 thin films were investigated using X-ray photoelectron spectroscopy as a means of evaluating surface oxygen impurities and nitrogen vacancies, which may correlate with the PEC OER performance and the electrical properties of the material.

Photoelectrochemical Water Oxidation Using Cobalt Phosphate‐Modified Nitrogen‐Doped Titania Nanotube Arrays

The synthesis of cobalt phosphate (CoPi)‐modified, nitrogen‐doped TiO2 nanotube arrays (N‐TNAs) for photoelectrochemical (PEC) oxygen evolution under visible light is reported. Because of the nitrogen doping, the N‐TNAs exhibit enhanced visible‐light activity toward the PEC water oxidation reaction. However, the performance is diminished as a result of self‐oxidation by photogenerated holes in the valence band of the N‐TNAs. Compared with the N‐TNAs, the CoPi/N‐TNAs prepared under optimal conditions show a twofold improvement in photocurrent generation and are also sensitive to light with wavelengths as long as 580 nm. Stable oxygen evolution with a Faradaic efficiency approaching unity is demonstrated using the CoPi/N‐TNA photoanodes under simulated sunlight for at least 2 h of operation.

Bifunctional metastable LaOCl@hcp-Ni nanocomposite via Mott-Schottky effect for improved photoelectrocatalytic and photocatalytic activities

Fabrication of low-cost, stable and highly efficient catalysts for clean energy and environmental control applications is an urgent task. In this work, we have successfully synthesized a multifunctional two-dimensional rare earth-based LaOCl@hcp-Ni heterostructure via a simple one-pot method. Here, the semiconductor LaOCl nanoparticles were well deposited on the metastable metal hcp-Ni, and the hexagonal close-packed structure of hcp-Ni matched the layered-structure LaOCl to form a highly active LaOCl@hcp-Ni Schottky catalyst. Furthermore, LaOCl@hcp-Ni were tested for Photoelectrochemical (PEC) oxygen evolution reaction (OER) in alkaline media and the photocatalytic (PC) degradation of Rhodamine B (RhB) in aqueous solution. LaOCl@hcp-Ni shows excellent PEC-OER catalytic activity and RhB degradation performance under artificial simulated sunlight. This enhancement of PEC and PC performance is due to the Schottky interface constructed by the coupling of hcp-Ni and LaOCl, which generates an interface electric field to effectively promote the transfer of photogenerated electrons from the semiconductor LaOCl to the metal hcp-Ni through the interface. Thus, energy band gap of LaOCl with oxygen defects is adjusted to the visible light region and their valence state of La is lowered, realizing high-efficiency visible light catalytic activity. Thus, it would be a potential rare earth-based Schottky catalyst, which can be used for the PEC oxygen evolution and the PC degradation of organic pollutants. • We successfully synthesized a bifunctional LaOCl@hcp-Ni nanocomposite as Schottky catalyst for PEC-OER and PC degradation of RhB. • Metal hcp-Ni with a metastable structure has high catalytic performance due to its low symmetry. However, its synthesis is difficult and usually requires high pressure conditions. We successfully synthesized hcp-Ni under mild oleylamine solution conditions at 320 °C. • This enhancement of PEC and PC performance is due to the Schottky interface effect between the semiconducting LaOCl and the metallic hcp-Ni, as well as the synergistic effect of the structural distortion and defects of the LaOCl.