Higher Photocurrent Density Research Articles

Boosting Photoelectrochemical Water Oxidation Performance of Ti–Fe2O3 Photoanode via NH2–MIL–53(FeCo) as a Cocatalyst

α–Fe2O3 is a promising photoanode that can be used for solar‐driven photoelectrochemical (PEC) water splitting. However, due to low carrier separation efficiency and slow water oxidation kinetics, the PEC performance of Ti–Fe2O3 is still severely hindered. Here, a novel inorganic–organic hybrid composite photoanode is prepared by depositing NH2–materials of institute Lavoisier (MIL)–53(FeCo) cocatalyst on the surface of Ti–Fe2O3 using solvothermal method. In the results, it is shown that the Ti–Fe2O3/NH2–MIL–53(FeCo) photoanode has a high photocurrent density (3.0 mA cm−2 at 1.23 V vs reversible hydrogen electrode (RHE), which is 5.1 times that of bare Ti–Fe2O3, and the initial potential of water oxidation also undergoes a negative change of about 100 mV. The separation efficiency of Ti–Fe2O3/NH2–MIL–53(FeCo) is significantly enhanced, and the charge injection efficiency increases from 17.6% to 68% at 1.23 V versus RHE. In the further research, it is suggested that the excellent PEC performance of Ti–Fe2O3/NH2–MIL–53(FeCo) may be attributed to an increase in carrier density, prolonged carrier recombination time, and an increase in exposed reactive sites. In this study, a new understanding for the design of Ti–Fe2O3 photoanodes with superior PEC performance based on metal organic framework modification is provided.

Design of type II quaternary double-decker heterostructure Cu-WO3-BiVO4-Bi2S3[sbnd]NiOOH photoanode for stable and efficient photoelectrochemical water splitting

BackgroundBismuth vanadate (BiVO4) and nickel oxyhydroxide (NiOOH) are the prominent photo(electro)catalysts for water-splitting photoelectrodes. The strong visible light absorbers of the Bi2S3 decorated type II photoanode of WO3/BiVO4/NiOOH efficiently improve the photo-excitons in the photoanodes. MethodsIn this work, type II semiconductors heterostructure photoanodes are fabricated as Cu:WO3/BiVO4/Bi2S3/NiOOH. The bottom layer of heavily Cu- doped n-type WO3 nanoplatelets is grown on FTO to make nano-heterostructure Cu:WO3/BiVO4 photoanodes. The Bi2S3 semiconductor has been grown on the BiVO4 by chemical bath deposition and NiOOH deposited using the photo-assisted electrodeposition method. The resulting periodically ordered BiVO4/WO3 platelets distinctly outperform by the Bi2S3 and NiOOH-decorated quaternary photoanodes. Significant findingsAs a result, the as-prepared photoanode shows a high photocurrent density of 6.85 mA cm−2 at 0 V vs. Ag/AgCl under the irradiation of 100 mW/cm2 AM 1.5 G simulated sunlight. With the higher photoactivity of Bi2S3 and NiOOH cocatalysts, the photoanode substantially gains stability at higher saturation photocurrents. Overall, the photoanode resulted in a low charge transfer resistance (387.4 Ohm.cm2) and a higher built-in potential of 180 mV, with 2.67 % of ABPE and 2.1 % of STH efficiencies at 0.3 V vs. Ag/AgCl.

Nickel-doped and surface fluorinated tungsten trioxide photoanode with enhanced photoelectrochemical water oxidation

To improve the slow charge transfer and high electron-hole recombination rate of tungsten trioxide (WO3), a nickel-doped and surface fluorinated WO3 photoanode is proposed. Compared with the unmodified and one-step modified WO3 photoanodes, the co-modified F/Ni-WO3 with two steps exhibits superior photoelectrochemical (PEC) performance with a significantly high photocurrent density of 1.03 mA/cm2 compared to 0.51 mA/cm2 of bare WO3 at 1.23 V vs. RHE. Ni doping can accelerate the kinetics of water oxidation and extend the light absorption range of the WO3 photoanode, while surface fluorination can enhance the surface electronegativity and hydrophilicity of the WO3 photoanode. The synergistic influence of the Ni doping and surface fluorination results in a lower carrier transport impedance, higher charge separation efficiency and larger electrochemically active surface of the WO3 photoanode which eventually contribute to the enhanced PEC performance for water oxidation.

Synthesis of a novel flower-like Bi4Ti3O12/AgI Z-type heterojunction for efficient photocatalytic removal of tetracycline antibiotic and RhB

Novel Flowerlike Bi4Ti3O12/AgI (BTO/AgI) Z-type heterojunctions were fabricated via a straightforward in-situ precipitation method. Notably, BTO/AgI exhibited significantly improved photodegradation efficiency for tetracycline (TC) and Rhodamine B (RhB). The rate constants for RhB and TC photodegradation were approximately 20.8 and 2.9 times higher than those of BTO alone, respectively. Furthermore, the photocatalytic efficiency of the BTO/AgI heterojunction is 1.4 times higher than that of the mixture of the two individual photocatalysts, indicating a robust interaction between BTO and AgI. This enhancement in photocatalytic performance was mainly attributed to the effective separation of photogenerated carriers facilitated by the Z-scheme heterojunction, which can be demonstrated by the highest photocurrent density (∼0.307 μA·cm−2) of BTO/AgI, surpassing BTO (∼0.073 μA·cm−2) and AgI (∼0.161 μA·cm−2) by approximately 4.12 and 1.91 times, respectively. Furthermore, three plausible photodegradation pathways of tetracycline were proposed. This study introduces a novel approach for designing and synthesizing high-efficiency Z-scheme photocatalysts for the degradation of TC and RhB in wastewater.

Effects of the phase transition on the photoelectrochemical properties of CuFe2O4 composite photoelectrode

In this study, CuFe2O4 was grown using various Cu:Fe source molar ratios. The morphological, structural, electrical, and photoelectrochemical properties of CuFe2O4 photoelectrodes with different structural phases based on molar ratios were analyzed. XRD and XPS were performed to systematically analyze the relationship between the structural and photoelectrochemical properties of the photoelectrode. XRD analysis revealed the phase transformation of CuFe2O4 from cubic to tetragonal phase and back to cubic phase as the Cu:Fe source molar ratio was varied. The crystallinity of Cu-rich cubic-CuFe2O4 was found to be superior to that of tetragonal-CuFe2O4. XPS analysis showed that the Cu-rich cubic-CuFe2O4 sample has higher Cu and Fe binding energies and more oxygen vacancies than the tetragonal-CuFe2O4 sample, which helps reduce carrier recombination. Additionally, cubic-CuFe2O4 samples prepared in Cu-rich conditions demonstrated high flat-band potential and low charge transfer resistance values. As a result, the cubic-CuFe2O4 photoelectrode sample under the Cu-rich condition exhibited a relatively high photocurrent density value. The highest photocurrent density value (-0.38mA/cm2 at -0.55 VSCE) was obtained with cubic-CuFe2O4 samples prepared under the Cu:Fe 3:1 condition.

Enhanced denitrification by sunlight–hematite: A neglected nitrogen flow pattern in red soil

Mineral-microbe interactions in the Earth's Critical Zone significantly influence elemental biogeochemical cycling and energy flow processes. This study addresses the key scientific question of how semiconducting minerals drive microbial nitrogen cycling. In the red soil environment, the presence of semiconducting minerals enhances the denitrification process mediated by facultative microorganisms (Pseudomonas aeruginosa PAO1) with denitrifying activity. Compared to darkness, light significantly enhanced the synergistic denitrification kinetic process of red soil and Pseudomonas aeruginosa PAO1 (1.87 times). Cyclic voltammetry shows that the P. aeruginosa PAO1-red soil synergistic system exhibits distinct redox peaks under light. The constant potential current curve and electrochemical impedance spectroscopy measurements reveal a high photocurrent density (1.0 μA/cm2) and minimal polarization resistance (102 Ω) under this condition. These findings confirm that the sunlight-red soil-P. aeruginosa PAO1 synergistic process has excellent electron generation and migration capacity, active redox reactions, and good electron compatibility. Additionally, the photoelectrons of semiconductive minerals in red soil profoundly impact the metabolic processes of microbial denitrification functional genes. Using real-time polymerase chain reaction (qPCR) gene array technology, the abundance of nitrogen metabolism functional genes in P. aeruginosa PAO1 increased by 200 % during the light-red soil synergistic process. Notably, denitrification-related genes (ureC, nirS1, gdhA, and nosZ2) were significantly upregulated. This study confirms that semiconducting minerals are involved in the nitrogen cycle pathway of microbial denitrification and supplements the theory of mineral-microbial synergistic element biogeochemical cycling in the natural environment.

Ultrathin B:NiCoOx-modified BiVO4 photoanode with abundant oxygen vacancies for photoelectrochemical glycerol conversion coupled with hydrogen production

Photoelectrochemical (PEC) conversion of glycerol (GLY) into high value-added chemicals coupled with clean hydrogen production can be achieved over a BiVO4-based PEC cell, but the low photocurrent density and poor photostability of the most BiVO4 photoanodes limit the PEC performance and sustainable application of solar resources. Herein, we construct a high-efficiency stable photoanode by decorating an amorphous ultrathin B-activation NiCoOx (B:NiCoOx) nanolayer with abundant oxygen vacancies (Ov) on the BiVO4 photoanode via a simple immersing process. We demonstrate the optimized B:NiCoOx/BiVO4 photoanode in the PEC GLY oxidation yields a high photocurrent density of 6.05 mA cm−2 at 1.23 VRHE, a formic acid (FA) production rate of 360.3 mmol m−2 h−1, a dihydroxyacetone (DHA) production rate of 228.4 mmol m−2 h−1, with simultaneously hydrogen production at the cathode. An intermittent 60-h PEC GLY oxidation assay results indicates the superb durability of the B:NiCoOx/BiVO4 photoanode. The outstanding PEC performance is predominantly ascribed to the amorphous ultrathin structure of the B:NiCoOx nanolayer (∼ 2 nm) and the abundant Ov, which effectually accelerates the photogenerated holes transport/extraction and offers more catalytic active sites for the PEC GLY oxidation. Moreover, the free state and adsorbed state •OH radicals originated from active oxygen are deduced to be responsible for the oxidation of GLY to FA and GLY to DHA. This study develops a sustainable BiVO4-based catalyst with high activity and photostability for the PEC GLY oxidation and hydrogen production.

Non-radical photoelectrochemical production of free chlorine from diluted chloride solutions on BiVO4

Free chlorine (FC) species are important oxidants for organic synthesis and environmental remediation. However, due to competitive water oxidation, it’s hard to obtain satisfied photoelectrochemical Faradic efficiency (FE) of FC via energetically unfavorable •Cl intermediate. Herein, we developed a non-radical strategy to realize efficient and stable FC production. High FE (86.2 %), high partial photocurrent density (2.8 mA/cm2) and excellent stability were achieved even under the conditions of diluted Cl (0.1 M) and neutral pH. Furthermore, compared with BVO, BVO@AgCl exhibited multi-fold faster rates for chlorine-mediated oxidations of styrene and arsenite with superior FEs (90.0 % vs. 59.4 %; 89.3 % vs. 47.3 %). Mechanistically, photogenerated holes are accumulated at AgCl sites (Cl+). FC is catalytically produced from the nucleophilic attack of Cl to Cl+, which bypasses •Cl intermediate and energetically outcompetes water oxidation. This work provides promising photoelectrochemical systems for highly efficient and stable production of FC, promoting high-value-added chemical synthesis and water treatment.

CuBi2O4/CuO photocathode with conformal CQD@Ni(OH)2 coating for stable solar water splitting

CuBi2O4 exhibits a high onset potential and theoretically high photocurrent density due to its well-matched bandgap for solar water splitting. However, factors such as low charge carrier mobility and severe charge recombination prevent CuBi2O4 from reaching its ideal photoelectrochemical performance, while photocorrosion of the Cu element severely compromises its stability. Herein, a convenient and low-cost chemical bath deposition method has been employed to combine carbon quantum dots (CQDs) with Ni(OH)2, resulting in the preparation of a conformal CQD@Ni(OH)2 layer-coated CuBi₂O₄/CuO heterojunction photocathode. Under AM 1.5G illumination, CuBi2O4/CuO/CQD@Ni(OH)2 illustrates a photocurrent density of −1.36 mA cm−2, which is 2.12 times higher than that of CuBi2O4/CuO. More importantly, the conformal coating of CQD@Ni(OH)2 effectively prevents photocorrosion induced by oxidation-reduction reactions of Cu2+/Cu. At 0.3 VRHE, the photocurrent of CuBi2O4/CuO/CQD@Ni(OH)2 remains at 76.4% after 10000 s of chopped light illumination, significantly outperforming the 48.9% retention observed for CuBi2O4/CuO photocathode after 3600 s of chopped light illumination. This work demonstrates that the CQDs and Ni(OH)2 are good candidates for the photoelectrode overlayer with significant synergetic effects.

Construction of Ag/AgCl@MIL-53(Fe): Achieving Efficient Photocatalytic Water Oxidation via the Plasma-Phase Silver and Heterojunction Synergistic Effect

The development of highly efficient water oxidation catalysts is a bottleneck in achieving artificial photosynthesis, as water oxidation is a complex process involving multiple electron and proton transfers. To further improve the photocatalytic water oxidation performance of MIL-53(Fe), a series of Ag/AgCl@MIL-53(Fe) samples with different Fe:Ag ratios were synthesized by hydrothermal methods and used in the photocatalytic water oxidation reactions. XRD characterization showed the successful preparation of Ag/AgCl@MIL-53(Fe) heterostructure catalysts. The reaction results showed that sample AAM-2 (Fe:Ag=5:1) had the best photocatalytic water oxidation performance, with the highest TOF value of 0.14 mmol/(g·s) and quantum efficiency of 39.0 % under the conditions of catalyst mass of 1 mg and pH=9.0 for boric acid-borax buffer solution. Measurements of photocurrent indicated that the AAM-2 samples doped with Ag/AgCl had higher photocurrent densities, thus improving the photocatalytic performance. This provides new insights for constructing highly efficient porous MOFs catalysts.

Structural and optical investigation of Nb5+-doped Sn3O4 for photoelectrochemical hydrogen production

We report herein, the microwave-assisted hydrothermal (MAH) synthesis of Nb5+-doped Sn3O4 nanoparticles for the photoelectrochemical production of hydrogen (H2). Nb5+ ions inside the Sn3O4 created structural defects, contributing to a local structural disorder, as confirmed by micro-Raman spectra. Photoluminescence spectroscopy indicated the decrease of the violet-blue–green visible emission after adding Nb5+, revealing the formation of alternative energy pathways for the electron/hole recombination. Through the morphological analysis, it was observed that the Nb5+ dopant slightly changed the morphology of nano-petals in Sn3O4. We demonstrate that the 3 % Nb5+ doped-Sn3O4 photoanode presented higher charge carrier mobility, higher photocurrent density, and an impressive H2 production of 1.50 mmol L−1 in a 3 h experiment, compared to the pure Sn3O4 material. The best performance of the Nb5+ doped Sn3O4 nanomaterial could be ascribed to the formation of new energy levels in the Sn3O4 band gap, thereby inhibiting the electron-hole pair recombination and positively affecting the photoelectrochemical response of the doped material.

Society based photovoltaic application of dye sensitized solar cell of Indium doped ZnO photoanode using cactus fruit via solvothermal method

In this work, Indium doped zinc oxide nanoparticles with various molar concentrations were synthesized by solvothermal method. The prepared nanoparticles were analysis using characterization. The structural properties of X-ray diffraction (XRD) used to obtain the hexogonal structure of nanoparticles. The surface morphology of prepared nanoparticles was magnification by Field Emission Scanning Electron Microscope (FESEM), The optical bandgap and functional groups were obtained by Ultra-Violet Visible spectra and Fourier Transform Infrared spectroscopy. Then the fabrication of dye sensitized solar cell based on indium doped ZnO photoanode using cactus dye. The performance of J-V characterization demonstrate a high short-circuit photocurrent density of 2.83 mA/cm2 and open circuit voltage of 0.63with relevant solar cell efficiency of 0.92 % whereas DSSCs made from pure ZnO NPs exhibited a current density of 8.02 mA/cm2 with 0.19 % efficiency. To increase the light-harvesting efficiency, both the photoanode and photons absorption could be optimized and it good response for UV-region. From this reports dye and photoanode are suitable to increase the efficiency of solar cell.

Copper-Surface-Mediated Synthesis of sp2 Carbon-Conjugated Covalent Organic Framework Photocathodes for Photoelectrochemical Hydrogen Evolution.

Sp2-carbon (sp2-c) covalent organic frameworks (COFs), featuring distinctive π-conjugated network structures, facilitate the migration of photo-generated carriers, rendering them exceptionally appealing for applications in photoelectrochemical water splitting. However, owing to the powdery nature of COFs, leaving anchor the sp2-c COFs powder tightly onto a conductive substrate challenging. Here, we propose a method for preparing photoactive substance-conductive substrate integrated photocathodes through copper surface-mediated knoevenagel polycondensation (Cu-SMKP), this approach results in a uniform and stable sp2-c COF film, directly grown on commercial copper foam (COFTh-Cu). The COFTh-Cu demonstrates a high H2-evolution photocurrent density of 56 μA cm-2 at 0.3 V vs. RHE, sustaining stability for 12 h. The as-prepared COFTh-Cu represents a 4.5-fold increase in current density compared to traditional spin-coating methods and outperforms most COF photocathodes without cocatalysts. This innovative copper surface-mediated approach for preparing photocathodes opens up a crucial pathway towards the realization of highly active COF photocathodes.

Visible light assisted periodate activation with porous C3N5 for tetracycline degradation: Enhanced electron-hole separation and reactive oxygen species formation

In this study, porous C3N5 (p-C3N5) was synthesized to activate periodate (PI) for tetracycline (TC) degradation under visible light condition. Experimental results confirmed that the porous structure in C3N5 created abundant defects as active sites, which not only increased the photoelectricity and electron-hole separation efficiency, but also promoted PI activation and reactive oxygen species formation, achieving significantly improved PI-assisted photocatalytic performance. In detail, p-C3N5 exhibited high photocurrent density which was 12.7 and 28.9 times as much as those of g-C3N5 and g-C3N4 respectively. Moreover, the p-C3N5/PI/vis system can achieve 80% TC removal rate within 10 min via ∙O2-, 1O2, IO3∙, ∙OH, h+ and electron transfer pathways. Furthermore, this system could maintain stable degradation capacity under a wide pH range, with less interference by inorganic anions, demonstrating its high reusability, robustness and environmental friendliness. Six possible degradation pathways of TC were proposed based on the detection of intermediate products and density functional theory calculation. Finally, the toxicity assessment showed a significantly reduction of TC bio-toxicity after treatment by p-C3N5/PI/vis system, and no formation of iodine by-products. It provides a deep insight into designing high efficiency and environmentally photocatalysts for activating PI to treat the antibiotic wastewater.

Nanoparticulated Vanadium Oxide on BiVO4 for Boosting Photoelectrochemical Glycerol Oxidation

Hydrogen (H2) has been spotlighted as ideal energy carrier due to its relatively higher energy density compared to fossil fuel and no carbon emissions during the energy generation. However, most of current produced H2 comes from as byproducts in fossil fuel reforming processes. To reduce dependence on fossil fuel in the H2 production process, photoelectrochemical (PEC) water splitting is considered as promising strategy for producing H2 using sustainable resources. Nevertheless, the insufficient efficiency in PEC water oxidation oxygen evolution reaction (OER) has limited overall PEC water splitting system efficiency due to its relatively high oxidation potential and sluggish catalytic kinetics. Furthermore, the low value of generated oxygen has been pointed out as obstacle from an economic perspective. To overcome these challenges, glycerol, byproduct of biodiesel, has been attracted numerous attentions as PEC oxidation resource since it has three hydroxyl groups and relatively lower oxidation potential than OER. Furthermore, glycerol oxygenated value-added products like dihydroxyacetone (DHA) can improve economics of PEC hydrogen production system. Upon these strengths, PEC glycerol oxidation reaction (GOR) provides improved strategy that generates value-added products in anodic part and green energy source (H2) in cathodic part simultaneously, which can replace PEC water splitting. Bismuth vanadate (BiVO4) is one of the most promising transition metal oxide based catalyst for PEC GOR due to its relatively narrow bandgap, high theoretical photocurrent density and deep positive valence band maximum (VBM) position. Additionally, although the surface kinetics of BiVO4 for OER has been sluggish, it potentially would be advantage for GOR with high production rate. However, the relatively instability of BiVO4 in acidic electrolyte during operation and lower selectivity of oxygenated products has hindered their practical application in PEC GOR. To solve these problems, introduction of nanoparticles as cocatalysts has been much studied for ameliorating surface kinetics and passivation the surface of photoanode. However, the interface between nanoparticles and photoanode with poor chemical interaction can induce the higher interfacial resistance and slow charge transfer efficiency rather. In this study, we present in-situ vanadium oxide (VOx) nanoparticle decoration on the surface of BiVO4 (VOx/BiVO4) via selective etching process using alkaline treatment for enhancing PEC GOR and we report the world best photocurrent density based on BiVO4 photoanode for GOR with high selective DHA production. VOx nanoparticles with an average size of 5 nm by selective etching process using alkaline treatment is decorated on the surface of BiVO4. The VOx promotes the surface reaction kinetics via modulating the fermi level and enhanced photovoltage of BiVO4 and improves long-term stability for GOR by compensation of V5+ and Bi3+, which combines both efficiency and stability. Furthermore, the surface decorated photoanode presents a 6.82 mA/cm2 (1.34-fold improvement) photocurrent density at 1.23 V versus the reversible hydrogen electrode (RHE) under 1 sun illumination, which has been attributed enhanced catalytic kinetics with upshifted fermi level and photovoltage of BiVO4. Moreover, the long-term stability of VOx/BiVO4 has been exhibited over 10 hours and the high selectivity for DHA is achieved. This study presents insight into the role vanadium of selective etched VOx on the surface of BiVO4 with low valence state than that of BiVO4 and improving the potential of BiVO4 based catalyst as GOR photoanode for high selective value-added DHA production using solar energy.

Synthesis and application of Ag3PO4 photocatalyst modified by g-C3N4 for tetracycline hydrochloride degradation

Finding highly efficient photocatalysts has practical significance for antibiotics degradation. In this work, g-C3N4 modified Ag3PO4 had been prepared via in-situ deposition method. Their photocatalytic activities were investigated through tetracycline hydrochloride (TCH) degradation under visible light. In summary, sample 6 wt% g-C3N4/Ag3PO4 (6 wt% CN/APO) exhibited a good degradation efficiency (72.1 %) to TCH within 30 min, while pure Ag3PO4 and g-C3N4 was only 57.4 % and 5.8 %, respectively. Because of the construction of heterojunction structure, 6 wt% CN/APO composite had low fluorescence intensity, high photocurrent density and low resistance, which were helpful for the rapid separation of photogenerated carriers. Therefore, the photocatalytic property of Ag3PO4 was obviously enhanced. In addition, sample 6 wt% CN/APO also showed excellent photocatalytic stability, and h+ played a main role in TCH degradation. Its possible photocatalytic mechanism was also elucidated.

Exploiting the efficiency of narrow band gap S-doped g-C3N4/Expanded Perlite/Red Ocher nanocomposite for high-level eliminating halogenated dye in Cool‐White‐SMD/H2O2 system

Hitherto, constructing prominent visible-light-driven g-C3N4/soil composites still suffers from several intricacies, including low specific surface area, inadequate charge separation, and a high band gap energy (Eg >2.7 eV). To address these drawbacks, sulfur atoms were introduced into g-C3N4 (S-doped g-C3N4 or SCN); thereby, Red Ocher (RO) and Expanded Perlite (EP) were grafted to SCN, which the engineered SCN/10EP/20RO nanocomposite divulged a higher specific surface area, further light-harvesting capability, narrower Eg, prolonged charge recombination process, lower the charge transfer resistance, and higher photocurrent density than bulk g-C3N4 (CN). Additionally, the formed S-scheme charge migration mechanism and the hole-trapping role of the hydroxyl functional groups synergistically engendered robust visible-light-driven catalytic performances under visible-light exposure. By enabling the heterogeneous photo-Fenton-like process, the Methylene Blue removal efficiency (MBRE) and the Total Organic Carbon (TOC) decontamination promptly elevated to 99.6% and 87.7% within 90 min under Cool-White-SMD/H2O2 condition, respectively. Manifestly, the kinetic reaction rate of the photo-Fenton-like process was 7.5 times higher than the primary photocatalysis, showcasing HO•had a determining role towards decent decomposing MB. After overviewing, our detailed findings straightforwardly corroborated that SCN/10EP/20RO nanocomposite would be an efficient, long-lasting, and green photocatalyst for eradicating halogenated organic pollution.

CuO nanoparticles for enhanced photoelectrochemical HER activity

Cupric oxide nanoparticles are a p-type semiconductor that can be used as a hole transport layer material in perovskite solar cells owing to their high electrical conductivity and stability. In the present work, CuO nanoparticles are synthesized using the hydrothermal technique, and their photoelectrochemical properties are studied through cyclic voltammetry. The X-ray diffraction patterns of the nanoparticles were analyzed for phase formation, revealing the monoclinic phase and further verified by the Rietveld Refinement. Thermogravimetric analysis shows a total weight loss of 13.47%. Transmission electron microscopy analysis suggests the formation of nanoparticles with an average size of 34 nm. The selected area electron diffraction analysis reveals the crystalline structure of the nanoparticles. The absorbance spectra of the nanoparticles were analyzed by UV–visible measurement, and Tauc's relation was used to estimate the optical bandgap. The XPS results align with the XRD results, indicating the formation of pure CuO nanoparticles. The developed catalyst's photoelectrochemical performance was investigated in the neutral solution for the hydrogen evolution reaction activity, and a high photocurrent density of −41.57 mA/cm2 was observed versus −0.6 V vs. RHE.

Green light all the way: Triple modification synergistic modification effect to enhance the photoelectrochemical water oxidation performance of BiVO4 photoanode

The recombination of photogenerated electron-hole pairs of the photoanode seriously impairs the application of bismuth vanadate (BiVO4) in photoelectrochemical water splitting. To address this issue, we prepared a Yb:BiVO4/Co3O4/FeOOH composite photoanode by employing drop-casting and soaking methods to attach Co3O4/FeOOH cocatalysts to the surface of ytterbium-doped BiVO4. The prepared Yb:BiVO4/Co3O4/FeOOH photoanode demonstrates a high photocurrent density of 4.89 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (RHE), which is 5.1 times that of bare BiVO4 (0.95 mA cm−2). Detailed characterization and testing demonstrated that Yb doping narrows the band gap and significantly enhances the carrier density. Furthermore, Co3O4 serves as a hole transfer layer to expedite hole migration and diminish recombination, while FeOOH offers additional active sites and minimizes surface trap states, thus boosting stability. The synergistic effects of Yb doping and Co3O4/FeOOH cocatalyst significantly improved the reaction kinetics and overall performance of PEC water oxidation. This work provides a strategy for designing efficient photoanodes for PEC water oxidation.

Boosting Acidic Water Oxidation on Hematite Photoanodes with Synergistic Effects of Ce‐Doped Co3O4 Nanoparticles

AbstractPhotoelectrochemical (PEC) water splitting is pivotal for addressing the clean and renewable energy demands. However, developing low‐cost, efficient, and robust non‐precious metal catalysts for the acidic oxygen evolution reaction (OER) remains a significant challenge. In this study, we introduced Ce to modulate the electronic structure of Co3O4, enhancing the stability of Co3O4 without compromising its activity. Ce‐doped Co3O4 nanoparticles were electrodeposited onto Ti‐doped hematite surfaces (Ce : Co3O4/Fe2O3), significantly enhancing the PEC performance for water splitting under acidic conditions. These catalysts achieved high photocurrent densities and exhibited prolonged stability. Functioning as p‐type semiconductors, the Ce : Co3O4 nanoparticles not only boosted light absorption but also formed a p‐n heterojunction with the Ti‐doped hematite. This heterojunction generated a built‐in electric field that facilitated the separation and transfer of photogenerated carriers, thereby improving charge separation efficiency. Additionally, these nanoparticles expanded the active surface area of hematite and served as a co‐catalyst, markedly accelerating the OER kinetics. The Ce : Co3O4/Fe2O3 photoanode achieved an impressive photocurrent density of 1.08 mA cm−2 at 1.23 VRHE in acidic media, demonstrating its enhanced activity and stability.