Improved Photoelectrochemical Performance Research Articles

A Plasma-Triggered O-S Bond and P-N Junction Near the Surface of a SnS2 Nanosheet Array to Enable Efficient Solar Water Oxidation.

A photoelectrochemical (PEC) cell can split water into hydrogen and oxygen with the assistance of solar illumination. However, its application is still limited by excessive bulk carrier recombination and sluggish surface oxygen evolution reaction (OER) kinetics. Taking SnS2 as an example, a promising layered optoelectronic semiconductor, Ar plasma treatment strategy was used to introduce a SnS/SnS2 P-N heterojunction and O-S bond near the surface of a SnS2 nanosheet array, simultaneously increasing the separation efficiency of photogenerated electron-hole pairs in the bulk and lowering the OER overpotential at the surface. The onset potential of the plasma-treated SnS2 nanosheet array shifts negatively to 0.16 V, and the photocurrent density at 1.23 V vs. RHE boosts to 2.15 mA cm-2 , which is 7 times that of pristine SnS2 . This work demonstrates a facile plasma treatment strategy to modulate the energy band structure and surface chemical states for improved PEC performance.

A Plasma‐Triggered O−S Bond and P−N Junction Near the Surface of a SnS2 Nanosheet Array to Enable Efficient Solar Water Oxidation

AbstractA photoelectrochemical (PEC) cell can split water into hydrogen and oxygen with the assistance of solar illumination. However, its application is still limited by excessive bulk carrier recombination and sluggish surface oxygen evolution reaction (OER) kinetics. Taking SnS2 as an example, a promising layered optoelectronic semiconductor, Ar plasma treatment strategy was used to introduce a SnS/SnS2 P−N heterojunction and O−S bond near the surface of a SnS2 nanosheet array, simultaneously increasing the separation efficiency of photogenerated electron–hole pairs in the bulk and lowering the OER overpotential at the surface. The onset potential of the plasma‐treated SnS2 nanosheet array shifts negatively to 0.16 V, and the photocurrent density at 1.23 V vs. RHE boosts to 2.15 mA cm−2, which is 7 times that of pristine SnS2. This work demonstrates a facile plasma treatment strategy to modulate the energy band structure and surface chemical states for improved PEC performance.

Au nanoparticles embedded in BiVO4 films photoanode with enhanced photoelectrochemical performance

In this work, we report the fabrication of Au nanoparticles embedded in BiVO4 films photoanode for photoelectrochemical (PEC) application by a facile electrochemical deposition and sputtering process. The Au NPs/BiVO4 films photoanode decorated with Co–Pi yields significantly improved PEC performance with a maximum photocurrent density of ∼3.1 mA cm−2 at 1.23 V versus RHE. The significantly enhanced performance could be attributed to the introduction of Au nanoparticles, which leads to enhancement of light absorption arising from surface plasmon resonance effect of nanosized Au and improved charge transfer and separation efficiency resulted by increased carrier density and charge transport property by the Au metal doping effect.

Reduced graphene oxide (RGO) on TiO2 for an improved photoelectrochemical (PEC) and photocatalytic activity

In this study, TiO2 nanoparticles (NPs) /reduced graphene oxide (RGO) composites were prepared by hydrothermal process and physiochemical, optical, photocatalytic and photoelectrochemical properties of prepared materials was investigated. Photocatalytic activity measurement showed that methylene blue (MB) photodegraded faster by TiO2-RGO composites compared to bare TiO2. Furthermore, photoelectrochemical (PEC) properties of TiO2 and TiO2-RGO electrodes were investigated under the illumination of a 150 W Xe lamp in 1M aqueous solution of KOH as the electrolyte. Moreover, TiO2-RGO electrodes showed greatly improved photocurrent density which is 3.3-fold higher than pure TiO2. Combined analyses of Mott-Schottky plots and electrochemical impedance spectroscopy (EIS) confirmed that RGO in the TiO2-RGO nanocomposite increased the donor concentration (ND), decreased recombination process of charge carriers (τD), thinner the space charge layer (WSCL) and reduced flat band potential (VFb) of the TiO2, thereby greatly enhancing the PEC performances of the TiO2 photoanodes. The improved PEC performance of the TiO2-RGO nanocomposite compared to TiO2 NPs attributed to great enhancement of electron transport through the RGO in the TiO2- RGO film and consequently charge separation.

Fabrication of WO3 photoanode decorated with Au nanoplates and its enhanced photoelectrochemical properties

In the present work, we improved the photoelectrochemical (PEC) performance of tungsten trioxide (WO3) photoanode by decorating WO3 plates with Au nanoplates. WO3 plates were fabricated on FTO-coated glass by hydrothermal treatment and Au nanoplates were incorporated by immersing the substrates in Au nanoplates solution under different periods of time. Our study revealed that compared with pristine WO3, the Au-WO3 nanocomposite performed enhanced photocurrent density under irradiation of the simulated sunlight. This improved PEC performance was benefited from the extension of light absorption resulting from the surface plasmon resonance effect of Au nanoplates at about 650 nm wavelength, and it was verified by UV–vis absorption spectra. The incident photon-to-current conversion efficiency measurements revealed improved photoactivity after decoration of WO3 with Au nanoplates. This study provided a facile method to decorate Au nanoplates on WO3 photoanodes with enhanced performance for solar energy conversion.

Facile preparation of BiVO4/FeVO4 heterostructure for efficient water-splitting applications

In this paper, a BiVO4/FeVO4 heterostructure photoanode was synthesized by electrospray technique, and its photoelectrochemical water oxidation performance was investigated. The maximum photocurrent density of 0.4 mA cm−2 at 1.23 VRHE was 6 times higher than that of pristine BiVO4 films (0.06 mA cm−2). Through the analysis of the electrochemical impedance spectroscopy (EIS) results, the improvement of photoelectrochemical performance could be attributed to the formation of heterostructure at the two-phase interface, which led to the effective separation of electron-hole pairs. This work offers a new effective strategy to construct semiconductor nanocomposites for efficient photoelectrochemical water oxidation.

3D Branched Ca-Fe2 O3 /Fe2 O3 Decorated with Pt and Co-Pi: Improved Charge-Separation Dynamics and Photoelectrochemical Performance.

The construction of junctions on hematite is an effective way to overcome the problems of slow charge separation and transfer kinetics, but constructing the junction is a significant challenge in photoelectrochemical (PEC) water splitting. Herein, a considerable improvement in PEC performance for α-Fe2 O3 was achieved following the introduction of a p-n homojunction between n-type α-Fe2 O3 and p-type Ca-doped α-Fe2 O3 through a facile hydrothermal method. The resultant 3D branched Ca-Fe2 O3 /Fe2 O3 enhanced the absorption intensity and reached a photocurrent density of 2.14 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE). The merit of the desired lattice matching of the buried p-n homojunction structure built an internal electric field, which led to appropriate band alignment. These results were supported by a series of photoelectrochemical measurements, in particular, surface photovoltage (SPV) measurements. For further improvement of the charge-separation efficiency, a combination of separated cocatalysts was established on the homojunction structure, in which Pt acted as the electron collector and was deposited on the bottom, and Co-Pi as the hole-extraction cocatalyst was inserted to accelerate hole transfer on the surface of the photoanode. The resulting Co-Pi/Ca-Fe2 O3 /Fe2 O3 /Pt branched nanorods showed a significant improvement in charge-separation efficiency and photocurrent density (2.94 mA cm-2 at 1.23 V vs. RHE). The present strategy, both the construction of the p-n homojunction and the coupling electron- and hole-transfer cocatalyst, could be expanded to many unstable or low-efficiency semiconductors for the design and fabrication of cost-effective photoanodes in PEC water splitting.

1D ZnFe2O4 nanorods coupled with plasmonic Ag, Ag2S nanoparticles and Co-Pi cocatalysts for efficient photoelectrochemical water splitting

Improving the absorption of visible light, accelerating the separation of carries and reducing the recombination of electron-hole pairs are critical to enhance photoelectrochemical (PEC) performance of ZnFe2O4. Herein, the ZnFe2O4/Ag/Ag2S films are firstly prepared with a photocurrent density of 0.91 mA/cm2 at 1.23 V vs. RHE, which is 9.10 times higher than that of pristine ZnFe2O4 (0.10 mA/cm2 at 1.23 V vs. RHE). On the basis, Co-Pi cocatalyst is deposited on ZnFe2O4/Ag/Ag2S to further optimize PEC performance of ZnFe2O4, the photocurrent density of ZnFe2O4/Ag/Ag2S/Co-Pi is 1.18 mA/cm2 at 1.23 V vs. RHE. The improved PEC performance of ZnFe2O4/Ag/Ag2S/Co-Pi films could be attributed to: (i) fast transmission of electron-hole pairs owing to 1D ZnFe2O4 NRs; (ii) surface plasmon resonance (SPR) effect of Ag nanoparticles; (ⅲ) visible light absorption is improved by sensitization of Ag2S nanoparticles; (ⅳ) Co-Pi cocatalyst decreases the recombination of electron-hole pairs by capturing holes. This work provides new insights for metal plasmas, sensitizers and cocatalysts synergistically modify photoanodes for efficient PEC water splitting.

Investigating the light harvesting capacity of sulfur ion concentration dependent SnS2 thin films synthesized by self-assembled arrested precipitation technique

In the present report, we have successfully synthesized sulfur ion concentration dependent SnS2 thin films using energy efficient, low cost and self-assembled arrested precipitation technique (APT). The influence of sulfur ion concentration on the crystallinity, optical tuning, surface morphology and photoconversion efficiency of SnS2 thin films was studied thoroughly. Optical absorption studies confirm a red shift in the absorption edge, which asserts its application as photoactive material. X-ray diffraction (XRD) and Raman studies confirmed the SnS2 thin film corresponds to the hexagonal crystal phase with preferential orientation along (001) plane, further the compositional analysis was verified by Energy dispersive x-ray (EDS) and x-ray photoelectron spectroscopy (XPS) studies. SEM images clearly highlight the transformation of surface morphology from nanospheres to compact interconnected nanograins with an increase in sulfur ion concentration; also HRTEM image confirms the formation of aggregated nanograins. Moreover, the diffraction rings in the SAED pattern suggest the hexagonal SnS2 structure which corroborates well with the XRD data. SnS2 as photoanode exhibits good photoelectrochemical (PEC) performance in I-/I3- redox electrolyte. Synthesized SnS2 thin films showed a significant enhancement in photocurrent conversion efficiency (0.09%) among reported values. Thus, sulfur ion concentration variation has the ability to alter the PEC performance of SnS2. Electrochemical Impedance Spectroscopy (EIS) study was used to analyze the charge transfer resistance (Rct) through the film. Finally, the improved PEC performance highlights the application of SnS2 photoanode in PEC cell.

Amorphous TiO2 coated hierarchical WO3 Nanosheet/CdS Nanorod arrays for improved photoelectrochemical performance

This work demonstrates hierarchical WO 3 nanosheet/CdS nanorod (WO 3 -NS/CdS-NR) arrays as a type-II heterojunction photoanode for improved photoelectrochemical (PEC) water splitting. Due to the synergistic effect of different constituents in the novel hierarchical structure, WO 3 -NS/CdS-NR arrays as a photoanode yield a photocurrent density of 5.4 mA cm −2 at 0.8 V versus reversible hydrogen electrode for sulfite oxidation. This is 12 times that of WO 3 -NS arrays (0.45 mA cm −2 ) and 3 times that of CdS-NR arrays (1.85 mA cm −2 ). In this hybrid WO 3 -NS/CdS-NR arrays photoanode, the favorable heterojunction between WO 3 and CdS enhances the charge separation efficiency and widens the light absorption spectrum. Furthermore, the optimization of the loading amount and size of CdS-NRs allows for a larger specific surface area as well as more effective light scattering, which further improves the PEC performance of WO 3 -NS/CdS-NR arrays. Finally, the coating of an ultrathin layer of amorphous TiO 2 also enhances the photostability of WO 3 -NS/CdS-NR arrays. Hierarchical WO 3 nanosheet/CdS nanorod arrays showed improved PEC performance than pristine WO 3 nanosheet and CdS nanorod arrays due to the synergistic effect of different constituents in the novel hierarchical structure. The coating of amorphous TiO 2 layer further increases the photostability. • Novel hierarchical WO 3 -Nanosheet/CdS-Nanorod arrays were reported. • Hierarchical structure plays a significant role in photocurrent enhancement. • An ultrathin layer of TiO 2 layer enhances photostability of WO 3 -Nanosheet/CdS-Nanorod arrays.

Nanoscale capillarity for mitigating gas bubble adhesion on arrayed photoelectrode during photoelectrochemical water splitting

One-dimensional (1D) arrayed photoelectrodes usually present superior performance in photoelectrochemical (PEC) water splitting. This superiority is known to be attributed to directional transport of photogenerated charge carriers. Herein, we show that in addition to this intrinsic charge transport property, a 1D arrayed structure introduces nanoscale capillary wetting, which is also believed to contribute to the improved PEC performance. Our theoretical model predicts that this morphology-dependent capillarity leads to the formation of a liquid film between the photoelectrode surface and the adhered bubble (the generated H2/O2 bubble), thus largely reducing the blockage of active sites at the bubble base. This prediction has been experimentally demonstrated by taking arrayed TiO2 nanorods as a model photoelectrode, with the observation of the PEC activity within the bubble base. This work extends our knowledge toward hydrodynamic functionality involved in morphology-controlled photoelectrodes for enhanced PEC performance.

Electrodeposition of highly porous ZnO nanostructures with hydrothermal amination for efficient photoelectrochemical activity

One step electrodeposition method has been used to realize highly porous ZnO pin hole (ZP) and ZnO rosette sheets (ZS) nanostructure based photo-anodes for efficient photoelectrochemical (PEC) splitting of water. Electrodeposited ZP and ZS based photo-anodes exhibit enhanced photocurrent density of 0.62 mA/cm2 and 0.76 mA/cm2 respectively (at a bias of 0.75 V). Further on hydrothermal amination (A), these electrodeposited ZP and ZS (A-ZP and A-ZS) nanostructure based photo-anodes had shown enhanced photocurrent density of 1.02 mA/cm2 and 1.27 mA/cm2, respectively. Surface morphology, evolution and elemental study were done using FESEM and EDX. Raman spectra of aminated photo-anodes have peaks at ∼270 cm−1 and ∼511 cm−1 related to stretching vibration mode between ZnN and ZnO. The peaks at wave number ∼558 cm−1 and ∼571 cm−1 is due to formation of ZnC bonds and because of complex defects respectively. ZnO exhibits low PEC activity, but on nano-structuring in the form of ZP and ZS improves its light absorption capacity. Hydrothermal amination red shifts (∼25 nm) the absorption band at ∼ 425 nm. The N and C act as electron reservoirs in A-ZP and A-ZS photo-anodes and efficiently separate the photo-generated electron/hole pairs and restrain charge recombination to generate photo-reactive sites. Electrochemical impedance spectroscopy (EIS) revealed that A-ZP and A-ZS had low charge transfer resistance compared to their bare counterparts. This lead to considerably improved PEC performance. An unprecedented increase in IPCE values in A-ZP and A-ZS can be assigned to the decrease in band gap and thereby significant enhancement in photocurrent density. These result in to proper charge segregation and improved charge transportation. The maximum value of IPCE is 9.6% for A-ZS sample and it is also clear that ZP and ZS nanostructured film have higher IPCE values at ∼400 nm than traditional ZnO thin film. A-ZP and A-ZS based photo-anodes have exhibited enhanced PEC performance as evident from IPCE measurements and thus can be a prospective candidate for PEC and optoelectronic applications.

Doping-Induced Amorphization, Vacancy, and Gradient Energy Band in SnS2 Nanosheet Arrays for Improved Photoelectrochemical Water Splitting.

Photoelectrochemical (PEC) water splitting is a promising strategy to convert solar energy into hydrogen fuel. However, the poor bulk charge-separation ability and slow surface oxygen evolution reaction (OER) dynamics of photoelectrodes impede the performance. We construct In- and Zn/In-doped SnS2 nanosheet arrays through a hydrothermal method. The doping induces the simultaneous formation of an amorphous layer, S vacancies, and a gradient energy band. This leads to elevated carrier concentrations, an increased number of surface-reaction sites, accelerated surface-OER kinetics, and an enhanced bulk-carrier separation efficiency with a decreased recombination rate. This efficient doping strategy allows to manipulate the morphology, crystallinity, and band structure of photoelectrodes for an improved PEC performance.

SnS2 Nanosheets/H-TiO2 Nanotube Arrays as a Type II Heterojunctioned Photoanode for Photoelectrochemical Water Splitting.

Improving the separation efficiency of photogenerated electron-hole pairs and the conductivity of electrons to photoanode substrates are critical to achieve high-performance photoelectrochemical (PEC) water splitting. Here, a SnS2 /H-TiO2 /Ti heterojunction photoanode was fabricated with SnS2 nanosheets vertically grown on hydrogen-treated TiO2 (H-TiO2 ) nanotube arrays on a Ti substrate. It showed a significantly enhanced photocurrent of 4.0 mA cm-2 at 1.4 V (vs. reversible hydrogen electrode) under AM 1.5 G illumination, 70 times higher than that of SnS2 /TiO2 /Ti. Kelvin probe force microscopy measurements indicated that photogenerated electrons could be easily transported through the SnS2 /H-TiO2 interface but not through the SnS2 /TiO2 interface. Through hydrogen treatment, defects were created in H-TiO2 nanotubes to convert type I junctions to type II with SnS2 nanosheets. As a result, a high efficiency of electron-hole separation at the SnS2 /H-TiO2 interface and a high electron conductivity in H-TiO2 nanotubes were achieved and improved PEC performance. These findings show an effective route towards high-performance photoelectrodes for water splitting.

Metal Chalcogenides on Silicon Photocathodes for Efficient Water Splitting: A Mini Overview

In the photoelectrochemical (PEC) water splitting (WS) reactions, a photon is absorbed by a semiconductor, generating electron-hole pairs which are transferred across the semiconductor/electrolyte interface to reduce or oxidize water into oxygen or hydrogen. Catalytic junctions are commonly combined with semiconductor absorbers, providing electrochemically active sites for charge transfer across the interface and increasing the surface band bending to improve the PEC performance. In this review, we focus on transition metal (di)chalcogenide [TM(D)C] catalysts in conjunction with silicon photoelectrode as Earth-abundant materials systems. Surprisingly, there is a limited number of reports in Si/TM(D)C for PEC WS in the literature. We provide almost a complete survey on both layered TMDC and non-layered transition metal dichalcogenides (TMC) co-catalysts on Si photoelectrodes, mainly photocathodes. The mechanisms of the photovoltaic power conversion of silicon devices are summarized with emphasis on the exact role of catalysts. Diverse approaches to the improved PEC performance and the proposed synergetic functions of catalysts on the underlying Si are reviewed. Atomic layer deposition of TM(D)C materials as a new methodology for directly growing them and its implication for low-temperature growth on defect chemistry are featured. The multi-phase TM(D)C overlayers on Si and the operation principles are highlighted. Finally, challenges and directions regarding future research for achieving the theoretical PEC performance of Si-based photoelectrodes are provided.

Electrophoretically Deposited MoSe2/WSe2 Heterojunction from Ultrasonically Exfoliated Nanocrystals for Enhanced Electrochemical Photoresponse.

The solar response ability and low-cost fabrication of the photoanode are important factors for the effective output of the photoelectrochemical system. Modification of the photoanode by which its ability to absorb irradiation can be manipulated has gained tremendous attention. Here, we demonstrated the MoSe2, WSe2, and MoSe2/WSe2 nanocrystal thin films prepared by the liquid-phase exfoliated and electrophoresis methods. Atomic force microscopy and high-resolution transmission electron microscopy show that the liquid exfoliated nanocrystals have a few layered dimensions with good crystallinity. Scanning electron microscopy demonstrated uniform distribution and randomly oriented nanocrystals, having a homogeneous shape and size. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectra confirm the equal contribution of MoSe2 and WSe2 nanocrystals in the formation of the MoSe2/WSe2 heterojunction. Because of superior absorption of MoSe2/WSe2 heterojunction in the visible region and type-II heterojunction band alignment, in situ measurement of heterojunction electrode shows almost 1.5 times incident photo-to-current conversion efficiency and photoresponsivity in comparison to individual material electrodes. Our result clearly indicates the influence of heterojunction formation between liquid exfoliated nanocrystals on effective separation of photogenerated exciton and enhances charge carrier transfer, which leads to the improvement in photoelectrochemical performance. Liquid exfoliated nanosheet-based heterojunction is attractive as efficient photoanodes for the photoelectrochemical systems.

Fluorine and tin co-doping synergistically improves the photoelectrochemical water oxidation performance of TiO2 nanorod arrays by enhancing the ultraviolet light conversion efficiency.

Fluorine and tin co-doped rutile TiO2 nanorod arrays are grown on fluorine-doped tin oxide substrates by a hydrothermal process and are used as photoanodes to perform photoelectrochemical water oxidation. Fluorine and tin co-doping synergistically enhances the ultraviolet light conversion efficiency of the resulting TiO2, which enables its photocurrent density of photoelectrochemical water oxidation to be more than four times that of the undoped samples. Such improvement in photoelectrochemical performance is attributed to changes in the electronic structure of the rutile TiO2 due to fluorine and tin co-doping. It is found that introducing tin into the matrix of rutile TiO2 can improve the charge separation efficiency because of the enhanced migration of photogenerated electrons from the conduction band of TiO2 to that of SnO2 that occurs at local sites, while fluorine doping can greatly reduce the recombination of the photogenerated electron-hole pairs due to the presence of the Ti3+ state that is produced to compensate for the charge difference between F- ions and O2- ions. It is envisaged that the fluorine and tin co-doped TiO2 nanorod arrays described will provide valuable platforms for wide photocatalytic applications that are not merely limited to photoelectrochemical water oxidation.

Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

Functional nanoscale interfaces that promote the transport of photoexcited charge carriers are fundamental to efficient hydrogen production during photoelectrochemical (PEC) splitting of water. Here, the realization of a functional one‐dimensional nanostructure achieved through surface engineering of hematite (α‐Fe2O3) nanorods with a TiO2 overlayer is reported. The surface‐engineered hematite nanostructure exhibits significantly improved PEC performance as compared to untreated α‐Fe2O3, with an increase in the maximum incident photon‐to‐current efficiency (IPCE) of nearly 400% at 350 nm. While addition of the TiO2 overlayer did not alter the lifetime of photoexcited charge carriers, as evidenced from transient absorption spectroscopy, it is found that the presence of TiO2 could enhance oxygen electrocatalysis by interfacial electron enrichment, largely attributed to enhanced O(2p)−Fe(3d) hybridization. Moreover, the interfacial electronic structure revealed from XANES measurements of the α‐Fe2O3/TiO2 nanorods suggests that photoexcited holes in α‐Fe2O3 may efficiently transfer through the TiO2 overlayer to the electrolyte while electrons migrate to the external circuit along the one‐dimensional nanorods, thereby promoting charge separation and enhancing PEC splitting of water.

Optimized preparation of Co-Pi decorated g-C3N4@ZnO shell-core nanorod array for its improved photoelectrochemical performance and stability

The cobalt-phosphate (Co-Pi) decorated g-C3N4@ZnO shell-core nanorod array (Co-Pi/g-C3N4@ZnO NRA) photoanode with broadened spectral response and optimized photoelectrochemical (PEC) performance was prepared. The g-C3N4@ZnO NRA was prepared via improved urea impregnation and calcination methods in semi enclosed environment. The g-C3N4 flexible slice shell was uniformly wrapped on ZnO nanorods core and the intimately contacted heterojunction was formed between the interface of g-C3N4 and ZnO. The g-C3N4@ZnO NRA promotes the separation and transfer of the photogenerated electron-hole pairs on g-C3N4 and ZnO under either visible light or white light illumination. The prepared g-C3N4@ZnO NRA was further electrodeposited with Co-Pi nanoparticles (NPs). The Co-Pi NPs can assist in the consumption of the photoinduced holes as well as pull the Fermi level potential of g-C3N4@ZnO NRAs towards the positive direction, resulting in the upward band bending at the band-edge position for Co-Pi/g-C3N4@ZnO NRAs and promoting the separation efficiency of the photogenerated electron-hole pairs. Consequently, the Co-Pi/g-C3N4@ZnO NRA exhibits an improved PEC performance under both visible light and white light illumination. In addition, g-C3N4 flexible slice shell decorated with Co-Pi NPs covered on the surface of ZnO NRAs core improved the stability of the ZnO NRA photoanode.

3D ordered urchin-like TiO2@Fe2O3 arrays photoanode for efficient photoelectrochemical water splitting

In this work, we report a three-dimensional ordered urchin-like TiO2@Fe2O3 arrays as photoanode for photoelectrochemical (PEC) water splitting application by a combination of colloid spheres template, atomic layer deposition and hydrothermal growth route. Combined with a further TiO2 surface passivation and decoration of water oxidation catalyst of cobalt phosphate (Co-Pi), the urchin-like TiO2@Fe2O3/TiO2/Co-Pi composite photoanode yields significantly improved PEC performance with an impressive photocurrent density of 1.58 mA cm−2 at 1.23 V vs. RHE and 3.6 mA cm−2 at 1.6 V vs. RHE, respectively. The significantly enhanced performance could be attributed to the 3D ordered composite structure design that provides large specific area and fast electron transport paths as well as improves the charge separation efficiency and water oxidation kinetics.