Photoanode Surface Research Articles

Solar-to-Pharmaceutical Raw Material Production: Photoelectrochemical Naphthoquinone Formation Using Stabilized BiVO4 Photoanodes in Acid Media.

In the quest for efficient use of solar energy to produce high-value-added chemicals, we first achieved the photoelectrochemical (PEC) diketonization of naphthalene, using a BiVO4/WO3 photoanode, to obtain naphthoquinone, an important pharmaceutical raw material with excellent efficiency by solar energy conversion. In the electrochemical (EC) reaction using F-doped SnO2 (FTO) substrates and a 0.5 M H2SO4 H2O-acetone (60 vol %) mixed solution containing 5 mM naphthalene, we produced a small amount of naphthoquinone evolution in the dark. However, naphthoquinone (ηNQ)'s Faradic efficiency and its evolution rate at 1.7 VAg/AgCl were only 28.5% and 0.48 μmol·cm-2·h-1, respectively. The PEC reaction using a WO3 photoanode had very low efficiency for naphthalene diketonization, with low ηNQ and evolution rate values at 1.1 VAg/AgCl of 0.3% and 0.039 μmol·cm-2·h-1, respectively. In contrast, the BiVO4/WO3 photoanode strongly enhanced the PEC reaction, and the ηNQ and evolution rates at 1.1 VAg/AgCl were boosted up to 37.5% and 4.7 μmol·cm-2·h-1, respectively. The evolution rate of the PEC reaction in the BiVO4/WO3 photoanode was 10 times higher than that of the EC reaction with the FTO substrate regardless of the very low bias voltage. This result suggests that the BiVO4-based photoanode was very efficient for the selective oxidation of naphthalene even in acid media because of the acetone-mixed electrolyte's anti-photocorrosion effect and the multilayering of WO3 and BiVO4. At a naphthalene concentration of 20 mM, the naphthoquinone evolution rate reached its maximum value of 7.1 μmol·cm-2·h-1. Although ηNQ tended to decrease with the increase in the electric charge, it reached 100% at a low bias voltage of 0.7 VAg/AgCl. An intensity-modulated photocurrent spectroscopy analysis indicated the rate constant of charge transfer at the photoanode surface to the naphthalene molecules was strongly enhanced at a low bias voltage of 0.7-1.1 VAg/AgCl, resulting in the high ηNQ value. The acid-resistant BiVO4/WO3 photoanode functioned in acetone-mixed electrolytes enabled the realization of a new PEC oxidation reaction driven by solar energy to produce high-value-added pharmaceutical raw materials.

Fabrication of In2O3 functionalized ZnO based nanoheterojunction photoanode for improved DSSC performance through effective interfacial charge carrier separation

This report is to address the limitation of conventional dye-sensitized solar cells (DSSCs) designed using pristine ZnO and N719 dye, which suffers from low performance due to the high charge carrier recombination and the formation of Zn2+-N719 complex over the surface of photoanode. Here we demonstrate the fabrication of ZnO–In2O3 heterojunction based photoanode to extend the charge carrier lifetime by effective interfacial transfer and to boost the light harvesting capacity in dye sensitized solar cells. This opted strategy also helps to prevent the formation dye complex over the photoanode surface. As a result, ZnO–In2O3 heterojunction with optimal composite ratio (1:1) could show better DSSC performance compared to remaining samples when applied as photoanode. Optical analyses and impedance measurements confirmed the enhanced visible light absorption and reduced charge transfer resistance of the composite photoanode due to the modification of ZnO using In2O3 as a counterpart. The results showed that the optimally designed photoanode with superior charge carrier life time and low charge transfer resistance exhibits power conversion efficiency (PCE) of 1.22%, which is nearly 4 times than the pristine ZnO.

Thermal and plasma enhanced atomic layer deposition of ultrathin TiO2 on silicon from amide and alkoxide precursors: growth chemistry and photoelectrochemical performance

Due to its low cost and suitable band gap, silicon has been studied as a photoanode material for some time. However, as a result of poor stability during the oxygen evolution reaction (OER), Si still remains unsuitable for any extended use. Ultra-thin titanium dioxide (TiO2) films have been used as protective coatings and are shown to enhance Si photoanode lifetime with added solar to hydrogen performance improvements through distancing the oxidation reaction away from the Si photoanode surface and improved charge transport through the anode. This study details the nucleation, growth chemistry, and performance of TiO2 thin films prepared via thermal and plasma enhanced atomic layer deposition (ALD) using both titanium isopropoxide and tetrakis(dimethylamido)titanium as the precursor material. The effect of post ALD treatments of plasma and air annealing was also studied. Films were investigated using photoelectrochemical cell testing to evaluate photoelectrochemical performance, and in-vacuum cycle-by-cycle x-ray photoelectron spectroscopy was used as the primary characterisation technique to study nucleation mechanisms and film properties contributing to improvements in cell performance. TiO2 grown by plasma enhanced ALD results in cleaner films with reduced carbon incorporation. However, despite increased carbon incorporation, thermally grown films showed improved photocurrent as a result of oxygen vacancies in these films. Post deposition annealing in a H2 ambient is shown to further improve photocurrent in all cases, while annealing in atmosphere leads to uniform film chemistry and enhanced photocurrent stability in all cases.

Spinel-Oxide-Integrated BiVO4 Photoanodes with Photothermal Effect for Efficient Solar Water Oxidation.

Spinel oxide materials have been widely used as oxygen evolution catalysts to enhance the photoelectrochemical (PEC) performance of photoelectrodes. Herein, we demonstrate that the water splitting efficiency of a photoanode can be further enhanced by introducing its photothermal effect. Under near-infrared radiation, the temperature of the NiCo2O4/BiVO4 photoanode increases moderately, leading to improved water oxidation kinetics and charge transport simultaneously. With the assistance of the photothermal effect, the obtained photoanode reaches a photocurrent density of 6.20 mA cm-2 at 1.23 V vs reversible hydrogen electrode. A series of spinel-type MCo2O4 oxides (M = Mn, Zn, Cu, and Fe) are deposited on the surface of the BiVO4 photoanode to show similar photothermally enhanced PEC performance. The research discovery provides a way for improving the catalytic activity of photoanode materials with a photothermal effect, which may be applied to various fields of energy conversion, including CO2 reduction, N2 fixation, and pollutant degradation.

Surface modification of p/n heterojunction based TiO2-Cu2O photoanode with a cobalt-phosphate (CoPi) co-catalyst for effective oxygen evolution reaction

The cobalt-phosphate decorated TiO2-Cu2O efficient heterojunction photoanode was successfully prepared using hydrothermal and electrodeposition methods. First, TiO2 was deposited onto fluorine-doped tin oxide-coated glass slides by the hydrothermal method, after which a layer of Cu2O was deposited by electrodeposition. Lastly, the surface of the TiO2-Cu2O electrode was further modified with cobalt-phosphate using photo-assisted electrodeposition. Prepared samples were characterized by X-ray diffractometry, field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy, and UV–Visible spectrophotometry. Substantial increase in photocurrent density, i.e., from 1.13 mA/cm2 to 1.66 mA/cm2 at 1.23 V vs reversible hydrogen electrode (RHE) was observed when the optimized Cu2O layer was applied to the bare TiO2 photoanode. Moreover, the highest photocurrent density, i.e., 1.94 mA/cm2 at 1.23 V vs RHE was obtained when the surface of the TiO2-Cu2O heterojunction photoanode was further modified using a cobalt-phosphate co-catalyst. The remarkable performance of the p-n heterojunction structure photoanode was mainly attributed to improved light harvesting in the visible region and improved charge dynamics due to the band alignment between TiO2 and Cu2O.

Inter-lamellar nanostructures-by-design for high-performance dual-photoelectrode photofuel cell based genosensor

Photofuel cells (PFCs) that integrate “clean-solar-to-electric energy” and “sensing platform” can enable next-generation biosensors for diverse health care and environmental applications. However, the inferior performance of photoelectrodes often results in insufficient solar-to-power conversion for reliable molecular detection. To overcome this problem, we developed a PFC-based genosensor by combining a Ti3C2Tx|CdS photoanode and a CuInS2 photocathode to generate significant output power for the reliable detection of miRNA-21. The innovative photoanode design involves (i) the insertion of CdS nanorods into multi-layered Ti3C2Tx to expand the interlamellar space from ~0.98 to ~1.34 nm for accommodating more biomolecules to improve the sensor sensitivity; (ii) the formation of the nanoscale Schottky junction to enhance photo-generated charge separation and photoelectric conversion rates. The hybridization of capture DNA, assistant DNA and miRNA-21 on the photoanode led to the initial quenching of output signal of prepared PFC. As a mimic enzyme, manganese porphyrin was intercalated into the conjugated DNA double chains to catalyze a precipitation reaction on the photoanode surface, which resulted in a further signal quenching. Due to the combination of specially designed PFC with dual signal quenching, the proposed PFC-based genosensor exhibited a dynamic detection range of 1 fM to 0.01 μM with a LOD of 0.053 fM for detection of miRNA-21.

Accelerated photoelectrochemical oxygen evolution over a BaTaO2N photoanode modified with cobalt-phosphate-loaded TiO2 nanoparticles

Because the oxygen evolution reaction (OER) involves a complicated four-electron process, reducing the overpotential for the OER by loading cocatalysts at as high a concentration as possible is critical for achieving efficient photoelectrochemical (PEC) water oxidation. However, such surface modifications should also be designed to not interfere with the bandgap photoexcitation of the light-absorbing materials. In the present study, cobalt-phosphate-loaded TiO2 (CoPi/TiO2) nanoparticles were used to modify a particulate BaTaO2N (BTON) photoanode, resulting in an improvement in the photoanode PEC OER performance. The TiO2 nanoparticles functioned as a transparent and conductive support with a high specific surface area to immobilize CoPi on the photoanode surface. Electrochemical measurements revealed that the CoPi/TiO2 modification led to improved reaction kinetics and that the electrochemically active surface area of the CoPi cocatalysts deposited on the electrode surface substantially increased by a factor of 7.45 as a result of the TiO2 modification. The CoPi/TiO2 modification increased the number of active sites on the surface of the particulate BTON photoanode and minimized the harmful influence of light shielding, thereby accelerating the OER kinetics.

Novel Anti-Interference Strategy for a Self-Powered Sensor: Mediator-Free and Biospecific Photocathode Interface.

As a new electrochemical sensing concept, a self-powered sensor shows a good application prospect in the field of analysis. However, it is still a great challenge to improve the anti-interference capability of sensors through reasonable design. In this study, we investigated the difference between the single photoanode and photocathode self-powered sensor and combined the advantages of these two aspects to fabricate a mediator-free self-powered aptasensor based on the dual-photoelectrode system, which combined the biological events from the photocathode. The biological events occurred at the photocathode could avoid the interference caused by the generated hole oxidation of reducing small molecules in the real sample on the photoanode surface, which was helpful to enhance the anti-interference capability of the sensor. Moreover, due to the sufficient Fermi level differentiation between two photoelectrodes, the redox mediator was not necessary. This could avoid the redox reaction caused by the introduction of extra electron donors or electron acceptors occurring before the photoelectrical behavior, thus improving the accuracy of the sensor. According to the influence of the generated biological conjugate on the external circuit, electron transmission between interfaces, and the obstruction of visible light irradiation, the sensitive and accurate detection of the analytical model was achieved. This work provided a proof-of-concept for the establishment of a mediator-free dual-photoelectrode self-powered sensing platform with high sensitivity and strong anti-interference performance.

Atomic layer deposition triggered Fe-In-S cluster and gradient energy band in ZnInS photoanode for improved oxygen evolution reaction

Vast bulk recombination of photo-generated carriers and sluggish surface oxygen evolution reaction (OER) kinetics severely hinder the development of photoelectrochemical water splitting. Herein, through constructing a vertically ordered ZnInS nanosheet array with an interior gradient energy band as photoanode, the bulk recombination of photogenerated carriers decreases greatly. We use the atomic layer deposition technology to introduce Fe-In-S clusters into the surface of photoanode. First-principles calculations and comprehensive characterizations indicate that these clusters effectively lower the electrochemical reaction barrier on the photoanode surface and promote the surface OER reaction kinetics through precisely affecting the second and third steps (forming processes of O* and OOH*) of the four-electron reaction. As a result, the optimal photoanode exhibits the high performance with a significantly enhanced photocurrent of 5.35 mA cm−2 at 1.23 VRHE and onset potential of 0.09 VRHE. Present results demonstrate a robust platform for controllable surface modification, nanofabrication, and carrier transport.

Developing SrTiO3/TiO2 heterostructure nanotube array for photocatalytic fuel cells with improved efficiency and elucidating the effects of organic substrates

Photocatalytic fuel cell (PFC) system is the next generation of energy converters which can consume organic waste to generate electricity. The magnitude of generated photocurrent in PFC is determined by charge separation efficiency of photoanode and the ability of photohole consumption by adsorbed organic molecules. In this study, the SrTiO3 (16.6 wt%) is deposited on the TiO2 photoanode surface to enhance the charge separation, as reflected by the increase in photocurrent. Further photocurrent responses of SrTiO3/TiO2 photoanode were studied in presence of different organic classes, including carboxylic acids, alcohols, amines and amides, which exhibits the dependence on the adsorption of the organics and on the associated oxidation mechanisms. The rate (ζ) of photocurrent generation per amount of adsorbed organic molecule was determined for the first time. Simple and short-chained molecules, such as methanol and formic acid, has a higher ζ value in the corresponding carboxylic acid and alcohol group. Furthermore, the direct hole scavengers show higher ζ values than the hydroxyl radical scavengers in PFC. The triethanolamine (TEOA) has the highest ζ value (131 μA μmol−1), which further results in the optimal PFC performance with a highest short-circuit current density 0.32 mA cm−2, open-circuit voltage 1.3 V and maximum power density output 0.098 mW cm−2.

Ab Initio Studies of Bimetallic-Doped {0001} Hematite Surface for Enhanced Photoelectrochemical Water Splitting

First-principles calculations based on density functional theory (DFT) were carried out to study the energetic stability and electronic properties of a bimetallic-doped α-Fe2O3 photoanode surface with (Zn, Ti) and (Zn, Zr) pairs for enhanced PEC water splitting. The doped systems showed negative formation energies under both O-rich and Fe-rich conditions which make them thermodynamically stable and possible to be synthesised. It is found that in a bimetallic (Zn, Ti)-doped system, at a doping concentration of 4.20% of Ti, the bandgap decreases from 2.1 eV to 1.80 eV without the formation of impurity states in the bandgap. This is favourable for increased photon absorption and efficient movement of charges from the valance band maximum (VBM) to the conduction band minimum (CBM). In addition, the CBM becomes wavy and delocalised, suggesting a decrease in the charge carrier mass, enabling electron–holes to successfully diffuse to the surface, where they are needed for water oxidation. Interestingly, with single doping of Zr at the third layer (L3) of Fe atoms of the {0001} α-Fe2O3 surface, impurity levels do not appear in the bandgap, at both concentrations of 2.10% and 4.20%. Furthermore, at 2.10% doping concentration of α-Fe2O3 with Zr, CBM becomes delocalised, suggesting improved carrier mobility, while the bandgap is altered from 2.1 eV to 1.73 eV, allowing more light absorption in the visible region. Moreover, the photocatalytic activities of Zr-doped hematite could be improved further by codoping it with Zn because Zr is capable of increasing the conductivity of hematite by the substitution of Fe3+ with Zr4+, while Zn can foster the surface reaction and reduce quick recombination of the electron–hole pairs.

Tin(IV) oxide nanoparticulate films for aqueous dye-sensitized solar cells

Reported solar conversion efficiencies of aqueous dye-sensitized solar cells (DSSCs) trail those of traditional organic electrolyte-based systems but offer the potential for lower environmental impact and overall cost. Methods for improving the photochemical activity of aqueous DSSCs could also impact progress in related fields such as solar fuels and solar batteries. This work presents the first study solely focused on the use of SnO2-based photoanodes for use in aqueous DSSCs. Material design and interfacial engineering are critical to the effective use of SnO2 in this context, and it is found that mesoporous films comprised of both large 1–2 μm flower-like SnO2 particles and small 10–20 nm spherical SnO2 particles provide better performance than films composed of only one particle type. Insulating TiO2 coatings further improve the performance, and this work presents a facile liquid phase deposition strategy under ambient conditions using an aqueous TiF62- solution that proves more effective than the widely used method with TiCl4 for fabricating high-performing SnO2@TiO2 photoanode surfaces. The best aqueous DSSCs reported here using cis-bis(isothiocyanato)-bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II) dye and simple I3-/I- electrolyte achieve a power conversion efficiency of 0.7% which eclipses the first reported TiO2-based DSSC using otherwise identical dye and electrolyte composition.

Fabrication of tungsten oxide photoanode by doctor blade technique and investigation on its photocatalytic operation mechanism

WO3 is a potential material candidate for construction of photoanode for solar driven water splitting. In this work, μm-thick porous WO3 photoanode is prepared by depositing a stable ink made of WO3 nanoparticles and Aristoflex velvet polymer in water using the doctor blade technique, followed by a sintering in air. The nature of WO3 nanoparticles, its loading mass on F-doped tin oxide electrode as well as sintering temperature are examined in order to optimize the photocatalytic activity of the resultant WO3 photoanode. The operation of WO3 photoanode is investigated by varying the light illumination direction and light incident intensity as well as changing the nature of the electrolyte. Dissolved tungsten in electrolyte is quantified by ICP-MS providing insights into the influences of electrolyte nature and operating conditions to the corrosion of WO3. It is proposed that the H2O2 and OH. radical generated as by-products of the photo-driven water oxidation on the photoanode surface are harmful species that accelerate the dissolution of WO3.

Investigation of a solar hydrogen generating system design for green applications

This study presents a unique dome photoanode design that can harvest the maximum delivered sun rays over the daytime due to its specific dome design to enhance the solar to hydrogen energy efficiency and improve the hydrogen mass generation rate. The photoanode and cathode domes are placed in a potassium hydroxide electrolyte inside two cylindrical vessels. The coupled electrochemical, exergy, energy, as well as fluid flow analyses, are conducted to examine the proposed photoelectrochemical cell designs using both COMSOL and Engineering Equation Solver software packages. The electrochemical process equations are simulated extensively to investigate the impacts of changing the illuminated electrode surface area, quantum efficiency, solar radiation intensity, and photocurrent density upon the corresponding energy efficiency as well as hydrogen generation rate. The thermodynamic balance equations are also developed to predict the exergy and energy for all inputs and outputs. The impact of electrolyte flow circulation on the oxygen bubble formation is formulated in a way to prevent the bubble coverage phenomenon. The numerical results showed that the hydrogen mass generation rate and solar to hydrogen efficiency are 26.16 μg/s and 4.38%, respectively, which happens at 600 W/m2 of solar irradiance, 10% quantum efficiency, and 569 cm2 illuminated electrode surface area. The maximum mass-based hydrogen generation rate and the overall energy efficiency, which are found to be 55.20 μg/s and 6.69%, are achieved at a 800 cm2 illuminated photoanode surface area, a 600 W/m2 solar radiation intensity, a 3.3 mA/cm2 current density, and a 10% quantum efficiency.

Modification of Ti-doped Hematite Photoanode with Quasi-molecular Cocatalyst: A Comparison of Improvement Mechanism Between Non-noble and Noble Metals.

Loading of molecular catalyst on the surface of semiconductors is an attractive way to boost the water oxidation activity. As active sites, molecular water oxidation cocatalysts show increasing attraction and application possibility. In order to compare the advantages between molecular catalysts with non-noble and noble metals, the loading of the Fe(salen) and Ru(salen) as cocatalyst precursors on the surface of Ti-Fe2 O3 was investigated Quasi-Fe(salen) and Ru(salen) improved the photocurrent density by 1.5 and 1.7 times compared to that of the original Ti-Fe2 O3 photoanode, respectively. The quasi-Fe(salen) could improve the conductivity and reaction kinetics on the photoanode surface. By contrast, the notable advancements could be attributed to more reaction sites for quasi-Ru(salen) as cocatalysts. Thus, non-noble quasi-Fe(salen) is a promising cocatalyst to replace the noble metal salen, and further optimization can be expected with regard to the precise control of reaction sites.

Photo-anode surface modification using novel graphene oxide integrated with methylammonium lead iodide in organic-inorganic perovskite solar cells

The novel graphene oxide sheet-methylammonium lead iodide (GO-MAPbI3) was used as photoanode surface modification and is used as a photosensitizer for perovskite solar cells. The multi-crystalline presence of GO-MAPbI3-prepared photo-anode surface and surface morphologies were observed by high-resolution electron transmission microscopy and electron scanning microscopy. The selected electron diffraction pattern of GO-MAPbI3 has also been observed in a multi-crystalline nature. GO-MAPbI3 containing the elementary composition was determined using X-ray photoelectron spectroscopy. They consist of Pb 4f5/2 and Pb 4f7/2 and have an energy binding value of 143.9 (eV) and 138.9 (eV). GO-MAPbI3 was a crystalline cubic black color confirmed by an X-ray diffraction pattern. From the Fourier transform infrared spectra, graphene oxide functional groups, methylammonium lead iodide internal hydrogen bonding between the C–N group attached to the C–H group and its corresponding values. The photo-current density-voltage curves are regulated by GO-MAPbI3 coated on a photo-anode giving 8.39% of the power conversion efficiency.

New naphthalenediimides as potential dyes for TiO2-sensitized solar cells

In this work new naphthalenediimides (NDIs) were synthesized and used as dyes in DSSC. The efficiency (η) of the DSSC is influenced by NDIs electronic and structural characteristics. It was found a better cell performance with the NDIs which have a broader absorption band shifted to the red color, high ƹ values, and more adsorption in the anode surface. The band gaps were determinate by UV–vis and cyclic voltammetry. The LUMO orbitals of most of the NDIs are above of the conduction band (CB) energy for TiO2 allowing the electron transfer process from the NDI to the photoanode, especially in those with a significant LUMONDI-CBTi energetic difference. Also, NDIs with polar groups in their structure presented higher η values due to a better adsorption on the photoanode surface, which allows a better energy capture compared with those with lower adsorption.

Influence of different concentrations of 4-tert-butyl-pyridine in a gel polymer electrolyte towards improved performance of Dye-Sensitized Solar Cells (DSSC)

Developing gel polymer electrolyte (GPE) can solve the safety issues faced by liquid electrolyte and allow easy fabrication of dye-sensitized solar cell (DSSC). However, its power conversion efficiency (η) still needs improvement by bettering any other parameters such as open-circuit voltage (VOC), short–circuit current (JSC) and Fill Factor (FF). Herein, 4-tert-butyl-pyridine (TBP) is used as an additive with different concentrations, and its effects on the GPE-TBP are studied. The addition of TBP is beneficial in DSSC employing GPE-TBP as it can adsorb on the surface of the mesoporous TiO2 photoanode, which leads to the shifting of the quasi-fermi level of TiO2 photoanode to a higher potential. This phenomenon enhances open-circuit voltage (VOC) of the DSSC from 615 to 750 mV upon addition of 7 wt% of TBP content to the GPE sample. However, taking into consideration all parameters in DSSC employing GPE-TBP, GPE sample containing 3 wt% of TBP shows the highest photovoltaic conversion efficiency (ɳ) of 8.11% under light illumination of 100 mW cm−2.

Optimization of photocatalytic fuel cells (PFCs) in the treatment of diluted palm oil mill effluent (POME)

Photocatalytic fuel cells (PFCs) are considered an advanced technology in wastewater treatment as they are able to remove organic based wastewater by using the principle of advanced oxidation processes (AOPs) and at the same time generate electricity. Despite PFCs being used to treat different types of organic based wastewater efficiently, the use of PFCs in palm oil mill effluent (POME) is still considered rare. Hence, the present research was carried out to determine the optimal conditions of contact time, pH, initial organic concentration and light intensity in order to remove the organic matter present in diluted POME. Our PFC system was constructed by using NaCl as the supporting electrolyte with ZnO/Zn as the photoanode and platinum wire as the cathode. The chemical oxygen demand (COD) removal efficiency and the amount of electricity generated was monitored in different optimization experiments using a conventional fluorescence light source. Under optimal conditions, the COD removal efficiency increased from 7% to 74 %, while the power density output also increased from 1.73 to 35.85 μW/cm2. The PFC was found to work optimally at pH 7 with a light intensity of 1300 lx for 6 h. Meanwhile, the scanning electron microscope (SEM) images revealed the high organic matter concentration in POME can lead to the deposition of an organic layer on the photoanode surface which subsequently reduced the COD removal efficiency to 17.4 %. This result has indicated that PFC is not suitable for treating the fresh POME directly from the mill, but it is more suitable for treating POME, from the last biological treatment pond.

Custom plating of nanoscale semiconductor/catalyst junctions for photoelectrochemical water splitting.

Photoelectrochemical water splitting under harsh chemical conditions can be promoted by dispersed transition metal nanoparticles electrodeposited on n-Si surfaces, without the need for classical protection layers. Although this method is simple, it only allows for poor control of metal morphology and geometry on the photoanode surface. Herein, we introduce templated nanoscale electrodeposition on photoactive n-Si for the customization of nanoscale inhomogeneous Schottky junctions and demonstrate their use as stable photoanodes. The photoelectrochemical properties of the so-manufactured photoanodes exhibit a strong dependence on the photoanodes' geometrical features, and the obtained experimental trends are rationalized using simulation.