Photoelectrochemical Hydrogen Generation Research Articles

Enhanced photoelectrochemical response of 1D TiO2 by atmospheric pressure plasma surface modification

In this paper we demonstrate the use of atmospheric pressure plasma jet (APPJ) to functionalize the surface of hydrothermally synthesized vertically aligned TiO2 nanorods (TNRs) for photo electrochemical (PEC) application. The TNRs functionalized with the atmospheric pressure He-plasma showed relatively higher crystallinity, improved light absorption, and change in the morphology with additional surface area, leading to an enhanced photocurrent density than that of the untreated. Achieving the PEC performance on par with the best in the literature, this APPJ treatment is shown to be a promising technique to obtain better functionality with TNR kind of materials and many other nano-micro systems for various applications such as PEC hydrogen generation.

Phase-junction Ag/TiO2 nanocomposite as photocathode for H2 generation

Developing anatase/rutile phase-junction in TiO2 to construct Z-scheme system is quite effective to improve its photoelectrochemical activity. In this work, the anatase/rutile phase-junction Ag/TiO2 nanocomposites are developed as photocathodes for hydrogen production. The optimized Ag/TiO2 nanocomposite achieves a high current density of 1.28 mA cm−2, an incident photon-to-current conversion efficiency (IPCE) of 10.8 %, an applied bias photon-to-current efficiency (ABPE) of 0.32 at 390 nm and a charge carriers’ lifetime up to 2000s. Such enhancement on photoelectrochemical activity can be attributed to: (i) the generated Z-scheme system in the anatase/rutile phase-junction Ag/TiO2 photocathode enhances the separation, diffusion and transformation of electron/hole pairs inside the structure, (ii) Ag nanodots modification in the anatase/rutile phases leading to the tuned band gap with enhanced light absorption and (iii) the formed Schottky barrier after Ag nanodots surface modification provides enough electron traps to avoid the recombination of photogenerated electrons and holes. Our results here suggest that developing phase-junction nanocomposite as photocathode will provide a new vision for their enhanced photoelectrochemical generation of hydrogen.

Photoelectrochemical concurrent hydrogen generation and heavy metal recovery from polluted acidic mine water

The feasibility of a solar-driven photoelectrochemical process to generate hydrogen fuel from metal mine polluted water while simultaneously recovering heavy metals has been explored.

Cobalt Sulfide as Photoelectrode of Photoelectrochemical Hydrogen Generation from Water

This study aimed to synthesize and characterize cobalt sulfide deposited on FTO by hydrothermal method and investigate its photoelectrochemical (PEC) water splitting performance. Cobalt sulfide thin films were produced by annealing at two different temperatures, namely, 400 and 500 °C. X-ray diffraction (XRD) and Fourier transform Raman spectroscopy were used to characterize the phase structure. Scanning electron microscopy was used to observe the morphology. Ultraviolet-visible spectroscopy and linear sweep voltammetry analyses were used to determine the thin-film band gap and evaluate the PEC water splitting performance, respectively. From the XRD and Raman analyses, all the samples produced consisted of mixed phases of Co3S4 and Co9S8. However, each sample contained different percentage phases. The sample annealed at 400 °C contained more Co9S8, whereas that annealed at 500 °C contained comparable amounts of Co3S4 and Co9S8. The morphologies of pre-annealed samples showed vertical flakes with diameters around 200-250 nm and flake thickness around 25-50 nm. When the temperature was increased from pre-annealing temperature to 400 and 500 °C, several flakes were destructed and formed spherical-like clusters. The Tauc plot from absorption analysis showed that the samples annealed at 400 and 500 °C produced similar band gaps at ~2.0 eV. The PEC performance analysis results show that annealing at 400 °C produced the highest photocurrent density of 10 μA/cm2 at a potential of -0.7 V.

Energy and environmental applications of Sn4+/Ti4+ doped α-Fe2O3@Cu2O/CuO photoanode under optimized photoelectrochemical conditions.

The most promising technique for directly converting solar energy into clean fuels and environmental remediation by organic dye degradation is photoelectrochemical (PEC) process. We introduced Sn4+/Ti4+ doped α-Fe2O3@CuxO heterojunction photoanode with complete optimization for PEC hydrogen (H2) generation and organic dye degradation. Improvement of photocurrent photo and reducing overpotentials under optimized conditions lead to enhancing PEC performances, degradation efficiency of organic compounds, and H2 generation generation rate. The optimized heterojunction photoanode (5TiFe@CuxO-D) showed IPCE exceeding 42% compared with pristine hematite (Fe0.01-8006h) nanostructures (28%). Additionally, all the optimized photoanodes showed higher PEC stability for 10h. Time-resolved PL spectra confirm the improved average lifetime for heterojunction photoanodes, supporting the enhanced PEC performance. Optimized 5TiFe@CuxO-D material achieved PEC H2 generation of ∼300μLh-1.cm-2 which is two times higher than pristine hematite's activity (150μLh-1.cm-2) and almost 99% degradation efficiency within 120min of irradiation time. Therefore, a state-of-the-art study has been explored for hematite-based heterojunction photoanodes reflecting the superior PEC performance and hydrogen, methyl orange (MO) dye degradation activities. The improved results were reported because of stable morphology and better crystallinity acquired through systematic investigation of thermal effects and hydrothermal duration, improved electrical properties by Sn/Ti doping into the lattice of α-Fe2O3 and optimization of CuxO deposition methods. The formation of well-defined heterojunction minimizes the recombination of the charge carrier and leads to effective transportation of excited electrons for the enhanced PEC performance.

Manipulating metal-oxygen local atomic structures in single-junctional p-Si/WO3 photocathodes for efficient solar hydrogen generation

Self-passivation in aqueous solution and sluggish surface reaction kinetics significantly limit the photoelectrochemical (PEC) performances of silicon-based photoelectrodes. Herein, a WO3 thin layer is deposited on the p-Si substrate by pulsed laser deposition (PLD), acting as a photocathode for PEC hydrogen generation. Compared to bare p-Si, the single-junctional p-Si/WO3 photoelectrodes exhibit excellent and stable PEC performances with significantly increased cathodic photocurrent density and exceptional anodic shift in onset potential for water reduction. It is revealed that the WO3 layer could reduce the charge transfer resistance across the electrode/electrolyte interface by eliminating the effect of Fermi level pinning on the surface of p-Si. More importantly, by varying the oxygen pressures during PLD, the collaborative modulation of W-O bond covalency and WO6 octahedral structure symmetry contributes to the promoted charge carrier transport and separation. Meanwhile, a large band bending at the p-Si/WO3 junction, induced by the optimized O vacancy contents in WO3, could provide a photovoltage as high as ∼ 500 mV to efficiently drive charge transfer to overcome the water reduction overpotential. Synergistically, by manipulating W-O local atomic structures in the deposited WO3 layer, a great improvement in PEC performance could be achieved over the single-junctional p-Si/WO3 photocathodes for solar hydrogen generation.

(Invited) Photoelectrochemical Hydrogen Generation Derived from Water Dissociation Under Supercontinuum Solar Light (25)

We created a two-compartment cell (2CC) separated by a bipolar membrane (BPM1) sandwiched between through-holed electrodes (THEs) assembly (BPMTHEA-2CC) based on the Golden Role for sustainable water splitting derived from water dissociation (WD) with a dual chemical bias (CB).2-4 The BPMTHEA-2CC provides an infinite supply of active reaction species, H+ and OH-, from water with an opposite bidirectional charge separation under appropriate applied voltage conditions. We have achieved hydrogen generation derived from WD with BPMTHEA-2CC using an oxygen evolving reaction active TH dimensionally stable anode (De Nora Permelec Ltd) prepared on Pt gauze. Liberated gas was analyzed using a gas chromatograph equipped with a MS-5A column and a thermal conductive detector (TCD). We succeeded in detecting appropriate amounts of molecular hydrogen generated in the cathode of a large-sized BPMTHEA-2CC, anolyte (water)|TH anode|BPM|TH cathode|catholyte (water), by imposing a voltage with less than the theoretical 1.23 V for water splitting at room temperature. We disprove the theory of water electrolysis established for hundreds of years. However, we still require external voltage for water electrolysis. Instead of external voltage, we have harnessed supercontinuum solar light throughout by designing optical tandem, wavelength multiplexing. Zero-bias photocurrent was observed by applying TH n-type semiconductor photoanodes to BPMTHEA-2CC. WD at the junction of BPM is considered to be originated in second Wien effect. Thus Au nanoparticle (Au-NP) was introduced into the junction of BPM to carry out plasmon-induced (PI) WD. With mixing different sizes of Au NPs, a wide range of absorption wavelengths would be attainable. Preliminary results obtained using Au-NP modified BPMTHEA-2CC were reported with two plausible mechanisms.3 A simple 4-port chamber has been developed to measure hydrogen concentrations down to 7.5 ppm and was used to demonstrate PEC zero bias hydrogen generation with harnessing supercontinuum solar light. V. J. Frilette, J. Phys. Chem., 60, 435 (1956).K. Sakamaki et al., AST2019, June 2-5, 2019, Awaji Yumebutai, Japan, O-24 (2019).K. Sakamaki et al., 236th ECS Meeting, Oct. 13-17, 2019, Atlanta, GA, USA, I04-1896 (2019).K. Sakamaki et al., J. Applied Electrochem. 49, 949-962 (2019). https://doi.org/10.1007/s10800-019-01337-8 Figure 1

Design and on-Sun Testing of Tandem III-V Photoelectrochemical Water-Splitting Systems

Photoelectrochemical (PEC) water-splitting systems utilize sunlight to directly split water to hydrogen and oxygen, providing a storable chemical fuel.1 While a variety of semiconductor material systems have demonstrated unassisted solar hydrogen production, III-V semiconductors have shown the highest reported solar-to-hydrogen (STH) conversion efficiencies and best device longevities.2–4 However, to date, work in the field has focused mostly on laboratory conditions, with few PEC systems having been tested outdoors using natural sunlight.In this work, we design III-V semiconductor systems with a molybdenum disulfide catalyst layer and demonstrate unassisted PEC hydrogen generation on-sun. First, a window and capping layer in conjunction with the MoS2 catalytic protection layer are shown to improve the photovoltage and durability of a single-junction pn-GaInP2 photocathode over a MoS2/pn-GaInP2 photocathode. Translating this top cell architecture to a tandem absorber device allows for more meaningful outdoor measurements and improved unassisted water-splitting performance. Specifically, we employ a tandem, lattice-matched GaInP2/GaAs (1.8/1.4 eV bandgaps) system that has been developed with high quality fabrication and yields>10% STH efficiency.2,3 An on-sun photoreactor platform was designed for PEC benchmarking and material testing that incorporates a 2-axis solar tracker and gas collection system.5 Insolation and environmental instrumentation at the co-located NREL Solar Radiation Research Laboratory provide a full record of the solar irradiance and environmental conditions, allowing for more accurate benchmarking of on-sun performance. PEC device characteristics were probed via current-voltage and chronoamperometry measurements under both natural and simulated sunlight illumination, while material structure is probed by XPS and SEM.The MoS2-protected tandem absorbers exhibit >10% STH efficiency under both laboratory and on-sun conditions. During a day of PEC testing under natural sunlight, >11 standard mL of hydrogen is generated with no applied bias. We will discuss challenges in catalyst and semiconductor stability and in cell design that limit PEC durability and hydrogen yield.

Influence of the spin deposition parameters and La/Sn double doping on the structural, optical, and photoelectrocatalytic properties of CoCo2O4 photoelectrodes

In this report, dual bandgap CoCo2O4 nanostructured films were spin-coated at different preheat temperatures (PHT) using different solution molarities (SM), Sn doping and La/Sn double doping levels. In addition to chemical compositions, various methods were used to investigate the structural, morphological, roughness, and optical properties. All the films are polycrystalline CoCo2O4, for simplicity Co3O4, spinel (AB2O4) cubic phase. The doping levels of Sn and La/Sn have strongly affected the surface morphologies and roughness parameters. PHT, SM, Sn% and La% show significant changes in lattice parameters, crystallite sizes, transmittance and reflectance spectra. Two bandgaps were detected in the range of 1.3–1.45 eV and 1.72–2.08 eV. With increasing PHT and decreasing SM, the refractive indices decreased and substantially modified with the inclusion of Sn and La in the matrix Co3O4. Among the applied electrodes for photoelectrochemical (PEC) hydrogen generation, the La/Sn-doped Co3O4 photocatalyst displays a catalytic H2 output rate of 134.50 mmol h−1/cm2 @-1Vwith IPCE% of ~52% @ 460 nm. The supreme values of ABPE% are 3.21%@-0.24V and 3.75%@-0.57V, which are the highest values yet for Co3O4-based photocatalysts. Interestingly, this photoelectrode shows photogenerated current densities of ~ −1.57 mA/cm2 at 0 V and −48.42 mA/cm2 at -1V, and photocurrent onset over −0.361 V. The PEC surface areas and Tafel slopes are also studied for the identification of the mechanism of PEC H2 production. The La/Sn doped-Co3O4 photoelectrode has been further tested for stability and reusability. This work has provided a new viewpoint to design highly active Co3O4-based photocatalysts for solar light-driven H2 generation.

“Green”, gradient multi-shell CuInSe2/(CuInSexS1-x)5/CuInS2 quantum dots for photo-electrochemical hydrogen generation

Colloidal quantum dots (QDs) are promising building blocks for the realization of future optoelectronic technologies. In particular, they are widely studied for photoelectric conversion, thanks to their low cost and high solar energy conversion efficiency. The majority of the QDs used in devices for photoelectrochemical (PEC) hydrogen generation is based on heavy-metal containing materials, such as Pb and Cd. Unfortunately, the use of these materials hamper their prospective to be commercially developed due to health and environmental concerns. In this work, by using a template assisted cation exchange procedure, we developed eco-friendly CuInSe2/(CuInSexS1-x)5/CuInS2 QDs based on a gradient multi shell architecture, exhibiting tunable Near Infra-Red (NIR) optical absorption and photoluminescence (PL) properties. The NIR QDs are used as sensitizer for mesoporous TiO2 and employed for PEC hydrogen production. The PEC device based on the gradient architecture showed a 200 % improvement compared to the simple core CuInSe2 QDs and 73 % compared to the core/shell structure. The enhancement is ascribed to favorable stepwise electronic band alignment and improved electron transfer rate with the incorporation of interfacial gradient layers. These results could pave the way for the synthesis of heavy-metal-free QDs, exhibiting broad application in emerging optoelectronic technologies.

Chlorophyll(a)/Carbon Quantum Dot Bio-Nanocomposite Activated Nano-Structured Silicon as an Efficient Photocathode for Photoelectrochemical Water Splitting.

Solar-driven water splitting is considered as a futuristic sustainable way to generate hydrogen and chemical storage of solar energy. Further, considering the technological competence, silicon is one of the potential materials for developing large-scale and cost-effective photocathodes (PCs), but it lacks efficacy and stability. Here, we show that chlorophyll(a)/carbon quantum dots (Chl/CQDs) bio-nanocomposite (b-NC)-decorated Si-nanowires (SiNWs) as PC can surpass the reported efficiency for photoelectrochemical (PEC) hydrogen generation along with stability. The optimized heterojunction (Chl/CQDs_SiNW) significantly enhances broad-band solar absorption and protects Si surface from corrosion. Further, the appropriate band alignment enforces efficient photogenerated charge separation and possesses directional exciton transport property via the Förster resonance energy transfer (FRET) mechanism. This synergic effect demonstrates an ∼18 times increase in photocurrent density (26.36 mA/cm2) compared to pristine SiNW PC at 1.07 V vs reversible hydrogen electrode (RHE). The efficiency reaches ∼7.86%, which is comparably the highest reported for hybrid Si-based photocathodes. Hydrogen evaluation rate was measured to be ∼113 μmol/h at 0.8 V vs RHE under 1 sun illumination. With Si-process line compatibility, this new finding opens a new direction toward the development of Si-based efficient and stable PCs at a large scale for commercial applications.

Hybrid surface passivation of PbS/CdS quantum dots for efficient photoelectrochemical hydrogen generation

Surface ligands facilitate the high dispersibility of colloidal quantum dots (QDs) during synthesis and storage, and also play a key role in passivating surface traps. The most commonly used ligands [oleic acid (OA) or oleylamine (OLA)] are insulating long organic linkers, which prevent efficient charge transfer between QDs and exhibit limited surface passivation, thus significantly reducing the overall performance of QDs based optoelectronic devices. Here we develop a solid-state ligands exchange process for PbS/CdS QDs sensitized TiO2 photoanode with hybrid inorganic ligands (I− and SCN−) to replace the original insulating OA ligands and passivate the surface traps. The hybrid surface passivation of PbS/CdS QDs removes ~75% of insulating OA ligands. The saturated photocurrent density of the photoelectrochemical (PEC) cells improves significantly through the hybrid ligand exchange process, reaching a value of 4.0 mA cm−2 which is more than two times higher compared to the control PEC cells. In addition, the long-term stability of PEC cells is better for the hybrid ligand exchange process (only 15% loss of its initial photocurrent density) than the control PEC cells (38% loss). Our results indicate that hybrid ligands engineering is a promising pathway to achieve high performance and stable PEC cells for hydrogen generation.

Over 17% Efficiency Stand‐Alone Solar Water Splitting Enabled by Perovskite‐Silicon Tandem Absorbers

AbstractRealizing solar‐to‐hydrogen (STH) efficiencies close to 20% using low‐cost semiconductors remains a major step toward accomplishing the practical viability of photoelectrochemical (PEC) hydrogen generation technologies. Dual‐absorber tandem cells combining inexpensive semiconductors are a promising strategy to achieve high STH efficiencies at a reasonable cost. Here, a perovskite photovoltaic biased silicon (Si) photoelectrode is demonstrated for highly efficient stand‐alone solar water splitting. A p+nn+ ‐Si/Ti/Pt photocathode is shown to present a remarkable photon‐to‐current efficiency of 14.1% under biased condition and stability over three days under continuous illumination. Upon pairing with a semitransparent mixed perovskite solar cell of an appropriate bandgap with state‐of‐the‐art performance, an unprecedented 17.6% STH efficiency is achieved for self‐driven solar water splitting. Modeling and analysis of the dual‐absorber PEC system reveal that further work into replacing the noble‐metal catalyst materials with earth‐abundant elements and improvement of perovskite fill factor will pave the way for the realization of a low‐cost high‐efficiency PEC system.

In Operando Generation and Storage of Hydrogen by Coupling Monolithically Integrated Photoelectrochemical Cell with Clathrate Hydrates Molecular Storage

Hydrogen production from water has been considered as one of the potential clean and futuristic alternates to fossil fuel. However, the development of a complete efficient system for hydrogen fuel coming from water lacks not only efficient, stable, and cost-effective generation but also off-line efficient storage. Herein, first, we present a newly designed monolithically integrated photoelectrochemical (PEC) device for hydrogen generation with a semitransparent MoOx/MoS2/FTO heterostructure as a photoanode and black 2D-MoS2/Si as a photocathode. This integrated cell eliminates the use of expensive metal (like Pt) as a counter electrode and enhances the overall stable H2 and O2 evolution, with a stable measured rate of 61 μmol/h and 28 μmol/h, respectively. The applied bias photon-to-current efficiency (ABPE) was measured to be ∼3.5% at −0.3 V vs reversible hydrogen electrode (RHE). Second, we demonstrate the storage of molecular H2 as solid hydrates, where the release of hydrogen from the hydrate requires no additional energy as it is not chemically bound to water. Operating at a moderate pressure of 10 MPa, we achieved hydrates of hydrogen with a maximum storage capacity of 1.3 wt %, which could be enhanced to 3 wt % with further fine-tuning of the process. The theoretical capacity of hydrogen storage in clathrate hydrates are ∼5 wt %. This concept of monolithic generation and molecular storage of hydrogen provides a complete long-demanding efficient and stable solution for large-scale commercial applications.

(Invited) Tuning the Optoelectronic Properties in Composite Systems for Sunlight Conversion

The processes of light absorption, exciton generation, charge separation and collection are critical to a series of applications, in which Sun light is either directly converted into electric power, like in solar cells, or transformed into chemical energy, like in photoelectrochemical hydrogen generation. All these processes are regulated by the optoelectronic properties of complex systems, in which the electronic band structure can be finely tuned by proper adjustment of chemical composition, size and morphology of the single components. Key element for the control of the optoelectronic properties is the modulation of the final electronic band structure. We will illustrate different strategies to obtain the desired optical and electrical properties in different complexes.One of the most interesting systems is composed of semiconducting nanocrystals exhibiting quantum confined effects (the so-called quantum dots, QDs), which act as light absorbing materials, and generate excitons as a consequence of photon absorption. [1] The QDs are typically coupled to a wide bandgap semiconductor (SnO2, ZnO, TiO2), which acts as electron transport material. In this case, the optoelectronic properties are determined by the dynamics of hole/electron dissociation and recombination, and the structure of the interface between the QD and the oxide semiconductor regulates such dynamics. Another option is to apply core-shell QDs, in which the relative band alignment between the core and the shell can be tuned by tailoring the interface between them. [2]We will illustrate a series of examples, [3] in which exciton dynamics in composite systems influences the functionality of the final device, including solar cells, photoelectrochemical hydrogen production and luminescent solar concentrators. Keywords: Composite systems; quantum dots; exciton dynamics; solar cells; photoelectrochemical hydrogen generation; luminescent solar concentrators

Photoelectrochemical Generation of Hydrogen and Formic Acid Using GaN Films Decorated with TiO2/Ag Nanoparticles Composite Structure as Photoelectrodes

In this study, hydrogen gas (H2) and formic acid (HCOOH) are simultaneously generated through direct water photoelectrolysis and CO2 reduction, respectively, by using Ag nanoparticles (Ag NP) decor...

Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy

We directly measure the electric dipole of InN quantum dots (QDs) grown on In-rich InGaN layers by Kelvin probe force microscopy. This significantly advances the understanding of the superior catalytic performance of InN/InGaN QDs in ion- and biosensing and in photoelectrochemical hydrogen generation by water splitting and the understanding of the important third-generation InGaN semiconductor surface in general. The positive surface photovoltage (SPV) gives an outward QD dipole with dipole potential of the order of 150 mV, in agreement with previous calculations. After HCl-etching, to complement the determination of the electric dipole, a giant negative SPV of −2.4 V, significantly larger than the InGaN bandgap energy, is discovered. This giant SPV is assigned to a large inward electric dipole, associated with the appearance of holes, matching the original QD lateral size and density. Such surprising result points towards unique photovoltaic effects and photosensitivity.

Wedged ß-In2S3 sensitized TiO2 films for enhanced photoelectrochemical hydrogen generation

Abstract As a photocatalytic material, the photoelectrochemical (PEC) performance of TiO2 is severely restricted due to wide band gap and rapid recombination of photogenerated electrons and holes. In order to effectively improve the PEC performance of TiO2, s-In2S3 photocatalysts with different morphologies are attached to TiO2 film by hydrothermal method. Compared with other TiO2/In2S3 samples, TiO2/In2S3-12 composites with wedged structure show an obviously broadened absorption range and effectively enhanced visible light absorption, and thus excellent PEC performance. Under visible light condition, the photocurrent density of TiO2/In2S3-12 sample reaches to 0.1256 at 0 V vs. SCE (saturated calomel electrode), which is about 90 times higher than that of pure TiO2 film. The experimental results evidence not only the sensitization of wedged In2S3 but also good carrier separation efficiency of TiO2/In2S3 heterojunction, which renders an effective way to improve the PEC water splitting efficiency.

Experimental investigation and optimization of integrated photovoltaic and photoelectrochemical hydrogen generation

This paper examines the transport phenomena and optimal performance of an integrated concentrated photovoltaic and photoelectrochemical hydrogen reactor. Individual components and the overall system are studied experimentally including the performance of the concentrator, spectrum-splitting mirror, electrolyser, reactor, and photovoltaic module. Integrating the solar concentration with a spectrum-splitting mirror allows simultaneous photovoltaic electricity generation and direct photonic energy conversion to produce hydrogen via electrolytic and photoelectrochemical water splitting. A multi-objective optimization of the integrated system is performed with machine learning and integration of a neural network. This yields a relationship between the system inputs and outputs. The neural network is used to optimize the overall system through a genetic algorithm. Numerical and experimental results are presented and discussed in the paper.

Cu2O nanoparticles sensitize TiO2/CdS nanowire arrays to prolong charge carrier lifetime and highly enhance unassisted photoelectrochemical hydrogen generation with 4.3% efficiency.

Effective separation of charge carriers and substantial prolongation of charge carrier lifetime are two vital issues for a photoanode to achieve highly efficient photoelectrochemical (PEC) hydrogen generation. Herein, a Cu2O-nanoparticle-sensitized TiO2/CdS (TiO2/CdS/Cu2O) nanowire array photoanode is fabricated via subtly combining successive ionic layer adsorption and reaction with a chemical bath deposition method. Both the type-II band alignment with a stair-like structure and a p-n junction are integrated into this ternary photoanode. The fabricated photoanode shows a significant enhancement in the PEC H2 production with 4.3% efficiency. The measurements of light absorption, photoluminescence and electrochemical spectra undoubtedly demonstrate that the enhanced PEC H2 generation is ascribed to the remarkable enhancement of visible-light absorbing ability, efficient space charge separation and substantial prolongation of charge carrier lifetime, which are achieved by the synergetic effects of the type-II band alignment with a stair-like structure and the p-n junction. The enhanced PEC H2 generation demonstrates the potential of the TiO2/CdS/Cu2O nanowire arrays as a photoanode to efficiently convert solar energy into chemical fuels.