Applied Bias Photon-to-current Efficiency Research Articles

Enhancing photoelectrochemical performance and stability of Ti-doped hematite photoanode via pentanuclear Co-based MOF modification.

Modifying photoanodes with metal-organic frameworks (MOFs) as oxygen evolution reaction (OER) cocatalysts has emerged as a promising approach to enhance the efficiency of photoelectrochemical (PEC) water oxidation. However, designing OER-active MOFs with both high photo- and electrochemical stability remains a challenge, limiting the advancement of this research. Herein, we present a facile method to fabricate a MOF-modified photoanode by directly loading a pentanuclear Co-based MOF (Co-MOF) onto the surface of a Ti-doped hematite photoanode (Ti:Fe2O3). The resulting Co-MOF/Ti:Fe2O3 modified photoanode exhibits an enhanced photocurrent density of 1.80mA∙cm-2 at 1.23V, surpassing those of the Ti:Fe2O3 (1.53mA∙cm-2) and bare Fe2O3 (0.59mA∙cm-2) counterparts. Additionally, significant enhancements in charge injection and separation efficiencies, applied bias photon-to-current efficiency (ABPE), incident photon to current conversion efficiency (IPCE), and donor density (Nd) were observed. Notably, a minimal photocurrent decay of only 5% over 10h demonstrates the extraordinary stability of the Co-MOF/Ti:Fe2O3 photoanode. This work highlights the efficacy of polynuclear Co-based MOFs as OER cocatalysts in designing efficient and stable photoanodes for PEC water splitting applications.

High-performance photoelectrochemical cells with MoS2 nanoflakes/TiO2 photoanode on 3D porous carbon spun fabric

A solar-driven photoelectrochemical (PEC) cell is emerging as one of the promising clean hydrogen generation systems. Engineering of semiconductor heterojunctions and surface morphologies of photoelectrodes in a PEC cell has been a primitive approach to boost its performance. This study presents that a molybdenum disulfide (MoS2) nanoflakes photoanode on 3-dimensional (3D) porous carbon spun fabric (CSF) as a substrate effectively enhances hydrogen generations due to sufficiently enlarged surface area. MoS2 is grown on CSFs utilizing a hydrothermal method. Among three different MoS2 coating morphologies depending on the amount of MoS2 precursor and hydrothermal growth time, film shape MoS2 on CSFs had the largest surface area, exhibiting the highest photocurrent density of 26.48 mA/cm2 and the highest applied bias photon-to-current efficiency (ABPE) efficiency of 5.32% at 0.43 VRHE. Furthermore, with a two-step growth method of sputtering and a subsequent hydrothermal coating, continuous TiO2/MoS2 heterojunctions on a porous CSF further promoted the photoelectrochemical performances due to their optimized bandgap alignments. Enlarged surface area, enhanced charge transfer, and utilization of visible light enable a highly efficient MoS2/TiO2/CSF photoanode with a photocurrent density of 33.81 mA/cm2 and an ABPE of 6.97 % at 0.87 VRHE. The hydrogen generation amount of the PEC cell with MoS2/TiO2/CSF photoanode is 225.4 μmol/L after light irradiation of 60 s.

MoO3/BiVO4 heterojunction modified with cobalt-manganese layered double hydroxide cocatalyst for photoelectrochemical water oxidation

To improve the charge recombination and poor oxygen evolution reaction (OER) kinetics of BiVO4, in this paper, a high-performance CoMn-LDH/MoO3/BiVO4 photoanode was synthesized by a simple electrodeposition and calcination method. CoMn-LDH/MoO3/BiVO4 shows a photocurrent density of 3.78 mA cm−2 at 1.23 V vs. RHE, which is 3.78 times higher than that of pure BiVO4 with negative shift onset potentials of 330 mV. The maximum applied bias photon-to-current efficiency (ABPE) and incident photon-to-current conversion efficiency (IPCE) are 1.24 % and 55.5 %, respectively, which are 13.8 and 12.5 times higher than those of pure BiVO4. In-depth studies demonstrate that the MoO3/BiVO4 heterojunction can better drive the transfer of photogenerated carriers and suppress bulk charge recombination, CoMn-LDH improves the OER kinetics and broadens the absorption of visible light, their synergistic effect significantly enhances charge separation and light harvesting of BiVO4. This work provides a facile electrodeposition method to fabricate highly efficient photoanodes for solar-driven water splitting.

Substitutional Cd Dopant as Photohole Transfer Mediator Boosting Photoelectrochemical Solar Energy Conversion of 2D Cd-ZnIn2 S4 Photoanode.

Fast recombination dynamics of photocarriers competing with sluggish surface photohole oxidation kinetics severely restricts the photoelectrochemical (PEC) conversion efficiency of photoanode. Here, a defect engineering strategy is developed to regulate photohole transfer and interfacial injection dynamics of 2DZnIn2 S4 (ZIS). Via selectively introducing substitutional Cd dopant at Zn sites of the ZIS basal plane, energy band structure and surface electrochemical activity are successfully modulated in the Cd-doped ZIS (Cd-ZIS) nanosheet array photoanode. Comprehensive characterizations manifest that a shallow acceptor level induced by Cd doping and superior electrochemical activity make surface Cd dopants simultaneously act as capture centers and active sites to mediate photohole dynamics at the reaction interface. In depth photocarrier dynamics analysis demonstrates that highly efficient photohole capture of Cd dopants brings about effective space separation of photocarriers and acceleration of surface reaction kinetics. Therefore, the optimum 2D Cd-ZIS achieves excellent PEC solar energy conversion efficiency with a photocurrent density of 5.1mA cm-2 at 1.23 VRHE and a record of applied bias photon-to-current efficiency (ABPE) of 3.0%. This work sheds light on a microstructure design strategy to effectively regulate photohole dynamics for the next-generation semiconducting PEC photoanodes.

Enhancing the hydrogen photo-production using zinc oxide films doped with iron, tin, and aluminum

Hydrogen is recognized as the most promising renewable energy source and can be efficiently produced through water photo-electrolysis green process. This study investigates the performance of ZnO nanorods doped with Fe, Al, and Sn at a 2 % molar ratio for hydrogen photo-production. The films were prepared using a combination of successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) methods. X-ray diffraction (XRD) analysis confirmed the hexagonal structure of the doped ZnO films with preferential growth along the (002) orientation, while energy-dispersive X-ray spectroscopy (EDX) confirmed their high purity. The doping with Al maintains the ZnO nanorods morphology while Fe, and Sn doping induced changes to overlapped nanoflakes/nanoflowers morphology. Optical analysis revealed a clear trend in the energy band gap, with Fe-ZnO film exhibiting the lowest value (2.95 eV), followed by Al-ZnO (3.03 eV), Sn-ZnO (3.07 eV), and ZnO (3.11 eV). The Fe-ZnO film also demonstrated the best performance as a photoelectrode for hydrogen generation, achieving optimized incident photon-to-current efficiency (IPCE) and applied bias photon-to-current efficiency (ABPE) values of 1.45 % and 0.20 % respectively, under 500 nm monochromatic illumination, with high reproducibility, and durability. These findings represent one step forward to developing ZnO-doped photoanodes for efficient and sustainable hydrogen green production.

Combining heterointerface/surface oxygen vacancies engineering of bismuth oxide to synergistically improve its solar water splitting performance

Solar-powered photoelectrochemical (PEC) water splitting is recognized as a strategy for addressing fossil resource and global warming concerns. The purpose of this paper is to demonstrate for the first time a facile method to fabricate dendritic nanostructured (DN) Bi:Bi2O3 heterointerface engineering junctions that possess abundant surface oxygen vacancies (OVs, DN Bi:Bi2O3-OVs/FTO), with outstanding PEC performance. The surface OVs serve as shallow donors and active reaction sites, whereas the Bi-metal bridges are used for fast electron transport. Furthermore, surface OVs can enhance the surface features of Bi:Bi2O3 heterointerfaces and boost their electrical conductivity and donor density. This greatly enhances electrolyte ion and electron mobility, resulting in rapid water oxidation reactions at the Bi:Bi2O3/electrolyte interfaces. By combining the Bi:Bi2O3 heterointerface junction and surface OVs, we are able to create an effective photoanode with 95 % charge injection efficiency, applied bias photon-to-current efficiency (ABPE) of 0.112 %, and a photocurrent response of 0.334 mA.cm−2 at 1.23 V vs. the reversible hydrogen electrode (RHE), which represents improvements of about 4.5 and 10 folds over that of pure DN Bi2O3 photoanode. It is possible to construct a variety of unique nanostructured electrodes with adjustable optical and electronic properties to be used in solar cells, energy storage, and PEC applications.

Cooperative catalytic behavior of Bi2S3 and ZrO2 nanoparticles on Bi2O3 photoanodes for promoted stability and solar driven photoelectrochemical hydrogen production

Photoelectrochemical water splitting via solar energy consumption is recognized as a strategy to address fossil resources and global warming concerns. Here, we reveal the co-catalytic effect of ZrO2 and Bi2S3 nanoparticles on nanostructured bismuth oxide (Bi2O3) electrodes synthesized by electrochemical deposition and an in-situ photoelectrochemical transformation process to fabricate heterostructured Bi2S3/Zr-Bi2O3 electrodes. The cooperative interaction between ZrO2 and Bi2S3 nanoparticles leads to a 12-fold enrichment in Bi2O3 electrode photocurrent density. The cooperation between the above features has considerably reduced the photocurrent onset potential, and improved the separation of charge carriers and optical features of the Bi2O3:Zr/Bi2S3 electrodes resulting in attaining an applied bias photon-to-current efficiency (ABPE) of 1.22 %. Through these examinations, it is possible to create a variety of nanostructured electrode films with adjustable optical and electronic features for solar cells, electrochemical energy storage, and PEC.

Synthesis of CuInS2 thin film photocathode with variation of sulfurization sources and Pt-In2S3 modification for photoelectrochemical water splitting

CuInS2 thin films have been successfully synthesized from the electrodeposition of copper (Cu), indium (In), and sulfurization on a molybdenum glass substrate as a water splitting photocathode. The effect of various sources of sulfurization with thiourea, sulphur, and H2S and modification with Pt-In2S3 on the character and performance of the material was observed. The success of the synthesis was confirmed by the typical peaks of 28.2, 46.8, and 55.4° on XRD, the presence of Cu, In, S elements on SEM-EDX analysis, the appearance of peaks of 298 cm−1 on Raman analysis, and the detection peaks of Cu 2p, In 3d, and S 2p with XPS analysis. Meanwhile, performance effectiveness and photoelectrochemical properties were analysed with photocurrent linear sweep voltammetry (LSV), applied bias photon-to-current efficiency (ABPE), and incident photon-to-current conversion efficiency (IPCE). Variations of sulfurization sources give different character and photocurrent results due to differences in the existing reaction mechanisms. While the modification treatment with Pt-In2S3 increased the resulting photocurrent. Sulfurization with H2S and modification of Pt-In2S3 gave the best results with a photocurrent of 18 mA cm−2, an efficiency of 3% ABPE, 47.2% IPCE, was evolved 467 μmol H2 and 230,1 μmol O2. This shows good potential as a water splitting material to produce environmentally friendly hydrogen fuel.

Integration of Ag Plasmonic Metal and WO3/InGaN Heterostructure for Photoelectrochemical Water Splitting.

In this study, a Ag/WO3/InGaN hybrid heterostructure was successfully developed by sputtering and molecular beam epitaxy techniques, to obtain unique Ag nanospheres adorned with cauliflower-like WO3 nanostructure over the InGaN nanorods (NRs). Exploiting the localized surface plasmon resonance of Ag, the Ag/WO3/InGaN heterostructure exhibited superior photoabsorption ability in the visible region (400-700 nm) of the solar spectrum, with a surface plasmon resonance band centered around 440 nm. Comprehensive analysis through photoluminescence spectroscopy, photocurrent measurements, and electrochemical impedance spectroscopy revealed that the Ag/WO3/InGaN hybrid heterostructure significantly enhances the charge carrier separation and transfer kinetics leading to improved overall photoelectrochemical (PEC) performance. The photocurrent density of the Ag/WO3/InGaN photoanode is 1.17 mA/cm2, which is about 2.72 times higher than that of pure InGaN NRs under visible light irradiation. The photoanode exhibited excellent stability for about 12 h. From the study, it has been found that the maximum applied bias photon-to-current efficiency (ABPE) is ∼1.67% at the applied bias of 0.6 V. The improved PEC water splitting efficiency of the Ag/WO3/InGaN photoanode is attributed to the synergistic effects of localized surface plasmon resonance (LSPR), efficient charge carrier separation and transport, and the presence of a Schottky junction. Consequently, the plasmonic metal-assisted heterojunction-based semiconductor Ag/WO3/InGaN demonstrates immense potential for practical applications in photoelectrochemical water splitting.

High efficiency Bi2S3/Bi2MoO6/TiO2 photoanode for photoelectrochemical hydrogen generation

The ternary Bi2S3/Bi2MoO6/TiO2 photoanode with waterfall-type energy level structure was engineered firstly for photoelectrochemical (PEC) water-splitting hydrogen generation. The results of XRD, SEM, EDS and TEM illustrated that Bi2MoO6 flakes were self-assembled in flower-ball shape on TiO2 nanoparticles via solvothermal reaction and the “green” Bi2S3 quantum dots (QDs) distributed in Bi2MoO6 flake edge through in-situ anion exchange process. UV-Vis. DRS and PL spectra showed that Bi2S3 QDs broadened the response range in visible and near-infrared region and waterfall-type energy level structure is helpful to inhibit the recombination of photo-generated electrons and holes. EIS spectra proved that Bi2S3 QDs amount and size can affect significantly photoanode/electrolyte interface transfer resistance and the minimum is down to 14.20 kΩ/cm2. The PEC device comprised with Bi2S3/Bi2MoO6/TiO2 photoanode, Ag/AgCl reference electrode, Pt counter electrode and Na2SO4 solution electrolyte exhibited high performance for water splitting: the photocurrent density maximum is 21.42 mA/cm2 and the applied bias photon-to-current efficiency (ABPE) maximum is 20.8%. However, the stability of PEC cell samples is a little poor and ABPE declines to 7.28% after 12 h. The ternary Bi2S3/Bi2MoO6/TiO2 photoanode with waterfall-type energy level structure can be also employed in other photovoltaic devices besides PEC cells.

Investigation of p-type spinel structure as photocathode thin films under neutral pH condition

Owing to the special electronic structure and earth-abundance, spinel structure-based oxides (AB2O4, A = Ni, Cu and B= Co, Fe) have considerable attractive for photo/electro/catalysis. In this work, AB2O4 thin films were synthesized via the spray pyrolysis method on FTO substrates and annealed at 550 °C for 1 h. The structural, morphology, optical and photoelectrochemical properties were studied. The crystalline results show that the thin films have a cubic spinel structure, and the morphology results show a fine grainy surface. The photoelectrochemical measurements in terms of photocurrent density, Incident Photon-to-Current Efficiency (IPCE) and applied bias photon-to-current efficiency (ABPE) were investigated for all samples under neutral pH condition. The results of photocurrent density were (109, 41, 28, 25) μA/cm2 and the IPCE results at 530 nm were 3.05% > 1.52% > 1.42% > 1.32% for CuCo2O4, NiCo2O4, CuFe2O4 and NiFe2O4 respectively under AM 1.5G (100 mW/cm−2) and applied bias −0.5 V. The band structure including the conduction/valence band was determined by Mott-Schottky plot revealing the ability of hydrogen production from neutral water.

Modulating Oxygen Vacancies in Lead Chromate forPhotoelectrocatalytic Water Splitting.

Although modulating oxygen vacancies in semiconductors has attracted broad interest in photocatalysis and photoelectrocatalysis, identifying the intrinsic roles of oxygen vacancies on photoelectrocatalytic properties is often elusive. In this work, the oxygen vacancies in a typical semiconductor lead chromate (PbCrO4 ) are regulated via controlling the oxygen chemical potentials of O-poor and O-rich post-annealing atmospheres. Oxygen vacancies identified in PbCrO4 can introduce electronically shallow energy levels and deep energy levels owing to the symmetry difference of oxygen atoms in the structure. A higher population of deep energy levels created under O-poor atmosphere induces the formation of more surface trapped states, resulting in a higher photovoltage for charge separation. Meanwhile, the existence of surface trapped states can significantly improve the charge injection efficiency of the PbCrO4 photoanode and enhance the water oxidation activity. By modulating oxygen vacancies in the PbCrO4 photoanode, a photocurrent density of 3.43mA cm-2 at 1.23V vs reversible hydrogen electrode (RHE) under simulated AM1.5G is acheived. Further passivation of surface trapped states and introducing the water oxidation cocatalyst CoPi lead to a record applied bias photon-to-current efficiency (ABPE) of 1.12%. This work provides a guide to understand the mechanism of oxygen vacancies in oxide-based semiconductor photocatalysis and photoelectrocatalysis.

Efficient BiVO4-Based Photoanode with Chemically Precipitated Hierarchical Cobalt Borate (Co-Bi) Oxygen Evolution Reaction Catalysts.

The integration of cobalt borate OER catalysts with electrodeposited BiVO4-based photoanodes through a simple drop casting technique was shown to provide an improvement of the photoelectrochemical performance of electrodes under simulated solar light. Catalysts were obtained by chemical precipitation mediated by NaBH4 at room temperature. Scanning electron microscopy (SEM) investigation of precipitates showed a hierarchical structure with globular features covered in nanometric thin sheets providing a large active area, whereas X-ray diffraction (XRD) and Raman spectroscopy highlighted their amorphous structure. The photoelectrochemical behavior of samples was investigated by linear scan voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) techniques. The amount of particles loaded onto BiVO4 absorbers was optimized by variation of the drop cast volume. The enhancement of photocurrent generation by Co-Bi-decorated electrodes with respect to bare BiVO4 was observed with an increase from 1.83 to 3.65 mA/cm2 at 1.23 V vs RHE under AM 1.5 simulated solar light, corresponding to a charge transfer efficiency of 84.6%. The calculated maximum applied bias photon-to-current efficiency (ABPE) value for optimized samples was 1.5% at 0.5 V applied bias. Under constant illumination at 1.23 V vs RHE, a depletion of photoanode performances was observed within an hour, likely due to the detachment of the catalyst from the electrode surface.

Improved photoelectrochemical hydrogen production performance of reduced graphene oxide-cadmium zinc sulfoselenide photoelectrodes prepared by a Facile In-situ Electrosynthesis method

Cadmium zinc sulfoselenide, CdZnSSe, and reduced graphene oxide-cadmium zinc sulfoselenide (RGO)-CdZnSSe composite-based photoelectrodes are fabricated using a facile, simultaneous co-electrodeposition by repetitive cyclic voltammetric (rCV) for the first time in literature. With this method, CdZnSSe particles are homogeneously decorated among the RGO sheets by controlling the composition of the composite structure and the film thickness with rCV. Photoelectrochemical, optical, and structural properties of photoelectrodes are evaluated to investigate their usability in photoelectrochemical hydrogen evolution. Decorating Cd0.8Zn0.2S0.2Se0.8 among RGO sheets leads to a slight red-shift of the absorption edge because of the less transparency of fabricated photoelectrode which decreases the band gap of composites. Among all Cd0.8Zn0.2SxSe1-x (x = 0.0, 0.2, 0.5, 0.8, 1.0) photoelectrodes, Cd0.8Zn0.2S0.2Se0.8 demonstrates the sharp rise in photocurrent density (4.08 mA cm−2). Decorating Cd0.8Zn0.2S0.2Se0.8 with RGO at an optimum composition jumps the photocurrent density up to 5.00 mA cm−2 in addition to the improved stability. The long-term stability of RGO(0.25)-Cd0.8Zn0.2S0.2Se0.8 is reported as 89.8% at the end of the 48th hour. The applied bias photon to current efficiency (ABPE) and Faradaic efficiency are obtained as 3.07% and 89.9%. Enhanced photoelectrochemical performance indicates the superiority of the proposed rCV technique for the fabrication of well-controlled photoelectrodes consisting of RGOCdZnSSe composites.

Charge Transport Enhancement in BiVO4 Photoanode for Efficient Solar Water Oxidation.

Photoelectrochemical (PEC) water splitting in a pH-neutral electrolyte has attracted more and more attention in the field of sustainable energy. Bismuth vanadate (BiVO4) is a highly promising photoanode material for PEC water splitting. Additionally, cobaltous phosphate (CoPi) is a material that can be synthesized from Earth's rich materials and operates stably in pH-neutral conditions. Herein, we propose a strategy to enhance the charge transport ability and improve PEC performance by electrodepositing the in situ synthesis of a CoPi layer on the BiVO4. With the CoPi co-catalyst, the water oxidation reaction can be accelerated and charge recombination centers are effectively passivated on BiVO4. The BiVO4/CoPi photoanode shows a significantly enhanced photocurrent density (Jph) and applied bias photon-to-current efficiency (ABPE), which are 1.8 and 3.2 times higher than those of a single BiVO4 layer, respectively. Finally, the FTO/BiVO4/CoPi photoanode displays a photocurrent density of 1.39 mA cm-2 at 1.23 VRHE, an onset potential (Von) of 0.30 VRHE, and an ABPE of 0.45%, paving a potential path for future hydrogen evolution by solar-driven water splitting.

Carbon quantum dots induced one-dimensional ordered growth of single crystal TiO2 nanowires while boosting photoelectrochemistry properties

TiO2 nanowire arrays (TNWAs) thin film of flexible substrates has great application potential in photoelectrochemical (PEC) hydrogen evolution. Moreover, the photoquantum efficiency of TNWAs can be effectively enhanced by reducing the nanoscale as much as possible or combining with other co-catalysts. This work presents a simple and effective strategy for the synthesis of ultrafine TiO2 nanowire arrays by a one-step hydrothermal method using CQDs as an inducer for single crystal growth. Meanwhile, CQDs recombine on the surface of TNWAs to form CQDs/TNWAs heterojunction during the synthesis process. The synthesized TNWAs have well ordered separability, whose average diameter is regulated at 11.21 nm with an average aspect ratio of 1097. PEC analysis showed that the performance of TNWAs was significantly improved compared with initial TiO2 with unregulated morphology. The charge separation efficiency increased by 120%, applied bias photon-to-current efficiency (ABPE) reached 0.37%(0.68 v vs RHE), and incident photon-to-current conversion efficiency (IPCE) reached 50.31% (380 nm). The influence of TiO2 nano-morphology optimization and formation of CQDs/TiO2 heterojunction on the PEC performance were discussed in detail.

Optimizing the morphology of titania nanorods for enhanced solar seawater splitting

Nanorod-TiO2 electrodes were obtained by a hydrothermal method in the presence of different concentrations of sodium chloride. The addition of NaCl during the synthesis promoted the formation of thinner, well-crystallized nanorods growing along the [001] crystallographic direction, while still, the most intense reflection is related to (101). The optimal electrode demonstrated applied bias photon to current efficiency (ABPE) of 0.24% in solar seawater splitting, which is among the highest reported efficiencies for the pristine TiO2 nanorods. Noteworthy, the ABPE of the obtained electrodes stayed intact during variation of the solar irradiation in the range of 0.2–1 Sun. It was also demonstrated that the efficiency of nanorod-TiO2 electrodes is higher for seawater splitting (0.5 M NaCl) than for water photoelectrolysis in the presence of 0.5 M Na2SO4. This phenomenon is the result of chloride evolution reaction taking place in addition to water oxidation. A gradual decrease in efficiency resulting from the low mobility of holes was observed for all electrodes. This conclusion was confirmed by experiments with a hole-scavenger (improved performance of the cell), as well as surface photovoltage measurements and electrochemical impedance spectroscopy.

Boosting solar fuel production of bismuth ferrite thin film by incorporating reduced graphene oxide

In this study, a facile chemical approach was utilized to successfully fabricate a porous bismuth ferrite (BiFeO3, BFO)/reduced graphene oxide (rGO) nanocomposite thin film as a photoanode for photoelectrochemical (PEC) water splitting. The BFO nanoparticles possess a pure rhombohedral distorted perovskite crystal structure and are grafted onto rGO nanosheets. BFO/rGO (BGO) thin film has smaller nanoparticles (around 100 nm) and higher porosity which provides a higher surface area compared to BFO. Moreover, BGO exhibits higher visible absorption, a narrower band gap energy of 1.95 eV, and a lower recombination rate of charge carriers. The BGO photoanode has a maximum photocurrent density of 0.451 mA.cm−2 at 1.23 V versus the reversible hydrogen electrode (RHE) under 100 mW.cm−2 illumination which is 2.5 times more than the BFO photoanode. The applied bias photon-to-current efficiency (ABPE) of BGO nanocomposite film is 0.21%, which is approximately 2.5 times that of BFO. The obtained results reveal an intimate heterostructure between BFO nanoparticles and rGO nanosheets. The charge separation and transfer of BFO are significantly boosted by incorporating the rGO. This study sheds light on the mechanism insights of enhanced PEC water splitting in BFO/rGO thin film, offering a new approach to the design and fabrication of high-efficiency photoanodes.

Reduced graphene oxide grafted on p-Si photocathode as a multifunctional interlayer for enhanced solar hydrogen production

Photoelectrochemical (PEC) water splitting has been intensively studied as a sustainable approach to directly convert intermittent solar energy into storable hydrogen fuels. Its practical application, however, has been tethered by the trade-off between photoelectrode efficiency and stability. Herein, this work demonstrates a facile strategy to design highly efficient and stable Si photocathodes by utilizing the reduced graphene oxide (rGO) as a multifunctional interlayer to bridge the Pt catalysts and p-Si. The covalently grafted rGO layer forms a Schottky junction with p-Si allowing effective charge carrier extraction required for high efficiency, and, simultaneously, protects the Si surface and anchors Pt catalysts with enhanced stability. Consequently, the as-fabricated Pt/rGO/p-Si photocathodes exhibit an impressive PEC performance under simulated AM1.5G illumination with a high applied bias photon-to-current efficiency (ABPE) of 4.9% and stability of over 110 hours, outperforming the Pt/p-Si control sample and state-of-the-art p-Si based photocathodes. In summary, this work offers a viable path for developing high-performance solar-to-fuel conversion devices in the future.

Self-Doped Carbon Dots Decorated TiO2 Nanorods: A Novel Synthesis Route for Enhanced Photoelectrochemical Water Splitting

Herein, we have successfully prepared self-doped carbon dots with nitrogen elements (NCD) in a simple one-pot hydrothermal carbonization method, using L-histidine as a new precursor. The effect of as-prepared carbon dots was studied for photoelectrochemical (PEC) water splitting by decorating NCDs upon TiO2 nanorods systematically by changing the loading time from 2 h to 8 h (TiO2@NCD2h, TiO2@NCD4h, TiO2@NCD6h, and TiO2@NCD8h). The successful decorating of NCDs on TiO2 was confirmed by FE-TEM and Raman spectroscopy. The TiO2@NCD4h has shown a photocurrent density of 2.51 mA.cm−2, 3.4 times higher than the pristine TiO2. Moreover, TiO2@NCD4h exhibited 12% higher applied bias photon-to-current efficiency (ABPE) than the pristine TiO2. The detailed IPCE, Mott–Schottky, and impedance (EIS) analyses have revealed the enhanced light harvesting property, free carrier concentration, charge separation, and transportation upon introduction of the NCDs on TiO2. The obtained results clearly portray the key role of NCDs in improving the PEC performance, providing a new insight into the development of highly competent TiO2 and NCDs based photoanodes for PEC water splitting.