Photoelectrochemical properties of p-type CuBi<sub>2</sub>O<sub>4</sub> prepared by spray pyrolysis of carbon-free precursor aqueous solution combined with post-annealing treatment

Wakishima, Kaisei; Higashi, Tomohiro; Nagaoka, Akira; Yoshino, Kenji

doi:10.1039/d3nj04878k

Cited by 5 publications

(1 citation statement)

References 66 publications

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“…The main XPS peak at 530.3 eV can be attributed to lattice O originating from the exposed FTO (O 2− (Sn)) present in the samples. 51 The shoulder peak at 531.4 eV corresponds to the adsorbed H 2 O (and/or hydroxy group), 51,52 while the peak at 529.3 eV, observed at lower BE, is associated with lattice O derived from the Rh oxide (O 2− (Rh)). 44,53,54 The intensity of the O 2− (Rh) peak in RhO x and RhCrO x was higher compared to that of bare RhNP and CrO x /RhNP, indicating the presence of Rh oxide on the surface.…”

Section: Characterization Of the Nanoparticulate Rho X And Rhcromentioning

confidence: 99%

Understanding the Activation Mechanism of RhCrO_x Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Higashi,

Seki,

Nandal

et al. 2024

ACS Appl. Mater. Interfaces

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Mixed oxides of Rh−Cr (RhCrO x ), containing Rh 3+ and Cr 3+ cations, are commonly used as cocatalysts for the hydrogen evolution reaction (HER) on particulate photocatalysts. The precise physicochemical mechanisms of the HER at the catalytic sites of these oxides are not well understood. In this study, model cocatalyst electrodes, composed of nanoparticulate RhCrO x , were fabricated to investigate the physicochemical mechanisms of the HER. Electroanalytical and X-ray photoelectron spectroscopic measurements revealed that nanoparticulate RhCrO x produces reduced Rh (Rh 0 ) species by maintaining an electrode potential more negative than 0.03 V versus the reversible hydrogen electrode (V RHE ). This results in significant enhancement of the HER activity. The catalytic activity for the HER stems from the reduced Rh species, and the inclusion of Cr 3+ (CrO x ) aided in the electron transfer process at the solid/ liquid interface, resulting in a higher current density during the HER. To achieve a solar-to-hydrogen efficiency of over 3%, the conduction band minimum of the particulate photocatalyst should be positioned more negatively than −0.10 V RHE . Moreover, the formation of electron trap states at potentials more positive than 0.03 V RHE should be avoided. This study highlights the importance of understanding the catalytic sites on metal oxide cocatalysts. Moreover, it offers a design strategy for enhancing the efficiency of photocatalytic water splitting.

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Section: Characterization Of the Nanoparticulate Rho X And Rhcromentioning

confidence: 99%

Understanding the Activation Mechanism of RhCrO_x Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Higashi,

Seki,

Nandal

et al. 2024

ACS Appl. Mater. Interfaces

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Scalable Reduced Graphene Oxide Conductive Layer‐Based Particulate Photocathodes for Photoelectrochemical Water Splitting

Sun,

Liu,

Liu

et al. 2024

Adv Materials Technologies

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Particle transfer method photoelectrodes show superior photoelectrochemical performance compared to traditional powder‐based methods, making them a promising solution for solar water splitting in sustainable energy. This study introduces an innovative nonvacuum particle transfer method for fabricating photoelectrodes on a conductive carbon substrate, addressing the challenges associated with the high costs and vacuum deposition processes of traditional methods. Utilizing a p‐type CuFeO2 powder semiconductor, a unique substrate is developed by applying a graphene oxide layer mixed with a small amount of silica binder on the particle layer's backside through ultrasonic atomization spraying. This layer is converted into multilayered reduced graphene oxide (ML‐rGO) via wet chemical reduction, resulting in a substrate boasting a high work function (4.8 eV), alongside remarkable chemical stability, mechanical strength, and conductivity. The fabricated CuFeO2 photocathode demonstrated an onset potential of 0.97 V versus RHE and a photocurrent density of 1.5 mA cm−2 at 0.6 V versus RHE for H2O2 reduction. Further enhancement is achieved by depositing Pt as a cocatalyst, which ensured stability for over 20 h in an alkaline medium for water splitting. This study sets a new benchmark for developing CuFeO2‐based photocathodes, paving the way for broader particle transfer method applications.

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Maximizing Oxygen Evolution Performance of NiFeO_x Semitransparent Electrocatalysts Applicable to Photoelectrochemical Water Splitting Device

Yoshiyama,

Higashi,

Xiao

et al. 2024

ChemNanoMat

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In photoelectrochemical (PEC) water splitting, semiconductor‐based photoelectrodes can improve reaction rates and durability by incorporating cocatalysts that serve as active sites for the water splitting process. However, achieving both high light transmittance and efficient catalytic activity is essential for these cocatalysts. This study aimed to optimize the surface loading of semitransparent NiFeOx thin‐film electrocatalysts to enhance the oxygen evolution reaction (OER) rates while maintaining high light transmittance. NiFeOx thin films were deposited on fluorine‐doped SnO2 (FTO) transparent conductive substrates, and the relationship between the NiFeOx loading amount (Γ) and the OER rate was examined using electrochemical techniques. The OER rate of NiFeOx on FTO (NiFeOx/FTO) was the highest at a Γ value of 0.20 μmol cm‐2. To further explore the connection between this optimized Γ and PEC activity, the impact of Γ on the PEC OER performance of visible‐light‐absorbing α‐Fe2O3 semitransparent photoanodes was evaluated as a model system. Applying the optimized Γ of NiFeOx to modify the α‐Fe2O3 surface also led to enhanced PEC OER performance. These findings highlight the critical role of surface design, specifically the optimization of cocatalyst loading and electrocatalytic activity, in improving PEC water splitting efficiency, providing valuable guidelines for future semitransparent photoelectrode development.

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Photoelectrochemical properties of p-type CuBi₂O₄ prepared by spray pyrolysis of carbon-free precursor aqueous solution combined with post-annealing treatment

Abstract: CuBi2O4 photoelectrodes were fabricated by a spray pyrolysis method using a carbon-free precursor solution. The optimized CuBi2O4 generated a photocurrent of −0.94 mA cm−2via H2O2 reduction at 0.6 VRHE under simulated sunlight illumination.

Cited by 5 publications

References 66 publications

Understanding the Activation Mechanism of RhCrO_x Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Understanding the Activation Mechanism of RhCrO_x Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Scalable Reduced Graphene Oxide Conductive Layer‐Based Particulate Photocathodes for Photoelectrochemical Water Splitting

Maximizing Oxygen Evolution Performance of NiFeO_x Semitransparent Electrocatalysts Applicable to Photoelectrochemical Water Splitting Device

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Photoelectrochemical properties of p-type CuBi2O4 prepared by spray pyrolysis of carbon-free precursor aqueous solution combined with post-annealing treatment

Abstract: CuBi2O4 photoelectrodes were fabricated by a spray pyrolysis method using a carbon-free precursor solution. The optimized CuBi2O4 generated a photocurrent of −0.94 mA cm−2via H2O2 reduction at 0.6 VRHE under simulated sunlight illumination.

Cited by 5 publications

References 66 publications

Understanding the Activation Mechanism of RhCrOx Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Understanding the Activation Mechanism of RhCrOx Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Scalable Reduced Graphene Oxide Conductive Layer‐Based Particulate Photocathodes for Photoelectrochemical Water Splitting

Maximizing Oxygen Evolution Performance of NiFeOx Semitransparent Electrocatalysts Applicable to Photoelectrochemical Water Splitting Device

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Product

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Photoelectrochemical properties of p-type CuBi₂O₄ prepared by spray pyrolysis of carbon-free precursor aqueous solution combined with post-annealing treatment

Understanding the Activation Mechanism of RhCrO_x Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Understanding the Activation Mechanism of RhCrO_x Cocatalysts for Hydrogen Evolution with Nanoparticulate Electrodes

Maximizing Oxygen Evolution Performance of NiFeO_x Semitransparent Electrocatalysts Applicable to Photoelectrochemical Water Splitting Device