CuO/NiOx thin film–based photocathodes for photoelectrochemical water splitting

Santos, Hugo Leandro Sousa dos; Corradini, Patrícia Gon; Andrade, Marcos A.S.; Mascaro, Lúcia H.

doi:10.1007/s10008-020-04513-5

Cited by 40 publications

(15 citation statements)

References 45 publications

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“…The characteristics of copper oxides can be improved by adding other oxides. Considering that NiO is a p-type semiconductor with a high mobility and concentration of photoinduced holes, and therefore acts as an effective cocatalyst in the reaction of hydrogen evolution [ 74 ], it was proposed to combine [ 77 ] copper and nickel oxides by depositing a thin layer of NiO x on CuO. The photocurrent density on the resulting binary material is –1.02 mA cm −2 at 0 V (SHE), which is slightly higher than for CuO (–0.92 mA cm −2 ).…”

Section: Strategies Of the Metal Oxide Photocatalyst Modificationmentioning

confidence: 99%

“…An additional function of cocatalyst nanoparticles is to extend the lifetime of charge carriers that reach the surface of the semiconductor by improving the electron–hole separation at the co-catalyst/semiconductor interface [ 107 ]. Various metals and other materials such as nickel oxide, iridium oxide, ruthenium oxide, cobalt phosphate, cobalt oxide and so forth, containing metals with variable valence states, are usually used as cocatalysts [ 74 , 77 , 108 , 109 , 110 , 111 , 112 , 113 , 114 ] ( Table 2 ).…”

Section: Strategies Of the Metal Oxide Photocatalyst Modificationmentioning

confidence: 99%

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Approaches for Modifying Oxide-Semiconductor Materials to Increase the Efficiency of Photocatalytic Water Splitting

2022

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The constant increase in the amount of energy consumed and environmental problems associated with the use of fossil fuels determine the relevance of the search for alternative and renewable energy sources. One of these is hydrogen gas, which can be produced by sunlight-driven photocatalytic water splitting. The decisive role in the efficiency of the process is played by the properties of the photocatalyst. Oxide materials are widely used as photocatalysts due to their appropriate band structure, high-enough photochemical stability and corrosion resistance. However, the bandgap, crystallinity and the surface morphology of oxide materials are subject to improvement. Apart from the properties of the photocatalyst, the parameters of the process influence the hydrogen-production efficiency. This paper outlines the key ways to improve the characteristics of oxide-semiconductor photocatalysts with the optimum parameters of photocatalytic water splitting.

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Section: Strategies Of the Metal Oxide Photocatalyst Modificationmentioning

confidence: 99%

Section: Strategies Of the Metal Oxide Photocatalyst Modificationmentioning

confidence: 99%

Approaches for Modifying Oxide-Semiconductor Materials to Increase the Efficiency of Photocatalytic Water Splitting

2022

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“…This creates a band bending structure and a depletion region within the p-n junction. It is important to point out that the band alignment and depletion region within the n-p junction, depends of many factors as: synthesis method, heat treatment, amount of components, dispersion, conductivity and structural defects [41][42][43].…”

Section: Photocatalytic Activitymentioning

confidence: 99%

“…The resulting values for the donor densities are given in Table 2 [46]. Observing the highest electron donor density of CuO-BT material, could be related with a greater amount of structural defects in the material and/or to a better dispersion of CuO over the BT structure [42,43]. Furthermore, this high carrier density of electrons could improve the conductivity through the BT material.…”

Section: Photocatalytic Activitymentioning

confidence: 99%

Effect of Co-catalyst (CuO, CoO or NiO) on Bi2O3–TiO2 Structures and Its Impact on the Photocatalytic Reduction of 4-nitrophenol

et al. 2020

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CoO, NiO or CuO oxides were employed as co-catalysts on Bi 2 O 3 -TiO 2 (BT) structure in the photocatalytic reduction of 4-nitrophenol under UV light irradiation. The intimate contact between the co-catalysts and base material contributed to an enhancement in the photocatalytic activity due to the formation of the p-n heterojunction that effectively separates charge carriers. CuO-BT, NiO-BT and Co-BT showed a reduction of 4-nitrophenol of 83%, 59% and 52% after 60 min under illumination, respectively, which are higher than that obtained with the BT semiconductor. The co-catalysts increase the donor density favoring the reduction of 4-nitrophenol. The donor density calculated for CuO-BT, NiO-BT and Co-BT was of N d = 15.5 × 10 18 cm −3 , N d = 12.4 × 10 18 cm −3 and N d = 9.41 × 10 18 cm −3 , respectively. The results were associated to that CuO and NiO oxides are considered as reduction co-catalysts while CoO oxide is used as oxidation co-catalyst.

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“…Cuprous oxide (Cu 2 O), an intrinsic p-type semiconductor material, has gained significant interest in PEC water reduction because of its elemental abundance and scalable synthesis techniques. − Moreover, Cu 2 O has a direct band gap energy of 2.0 eV, which enables a theoretical photocurrent density ( j ph ) of 14.7 mA/cm 2 and a solar-to-hydrogen (STH) conversion efficiency of 18% under a standard 100 mW/cm 2 AM1.5G illumination . However, the poor stability of Cu 2 O in aqueous solutions hinders its PEC water splitting application .…”

Section: Introductionmentioning

confidence: 99%

Cu₂O/ZnO p–n Junction Decorated with NiO_x as a Protective Layer and Cocatalyst for Enhanced Photoelectrochemical Water Splitting

Jian

Kumar

Sun

2020

ACS Appl. Energy Mater.

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Cuprous oxide (Cu 2 O) has attracted much interest as a photocathode for photoelectrochemical (PEC) water splitting because of its elemental abundance and the favorable band gap, but its poor stability in aqueous solutions hinders the practical PEC application. Compared to the mostly used TiO 2 and noble metal cocatalysts for coating the Cu 2 O photocathode, this work demonstrates a strategy to fabricate a noble metal-free photocathode. We construct a Cu 2 O/ZnO p−n junction photocathode decorated with the NiO x layer as both the protective layer and the hydrogen evolution reaction (HER) cocatalyst. The NiO x cocatalyst exhibits a small Tafel slope of 35.9 mV/ dec and a very low overpotential of 115 mV to drive a current of 10 mA/cm 2 , which are very close to the HER activity of the noble metal platinum. With decorated NiO x , the Cu 2 O/ZnO/NiO x photocathode exhibits significantly improved stability and photocurrent density with a Faradaic efficiency of H 2 gas evolution of 95 ± 4%, distinctly outperforming the Cu 2 O, Cu 2 O/ZnO, and Cu 2 O/ZnO/TiO 2 photocathodes. Moreover, electrochemical impedance analysis evidenced that NiO x as a cocatalyst also facilitates the transfer of photogenerated electrons across the electrode/electrolyte interface for water reduction. This work demonstrates that NiO x is not only a stable protective layer against corrosion but also a highly active H 2 evolution cocatalyst. These findings provide new insights for the design of noble metalfree photocathodes toward solar fuel development.

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CuO/NiOx thin film–based photocathodes for photoelectrochemical water splitting

Cited by 40 publications

References 45 publications

Approaches for Modifying Oxide-Semiconductor Materials to Increase the Efficiency of Photocatalytic Water Splitting

Approaches for Modifying Oxide-Semiconductor Materials to Increase the Efficiency of Photocatalytic Water Splitting

Effect of Co-catalyst (CuO, CoO or NiO) on Bi2O3–TiO2 Structures and Its Impact on the Photocatalytic Reduction of 4-nitrophenol

Cu₂O/ZnO p–n Junction Decorated with NiO_x as a Protective Layer and Cocatalyst for Enhanced Photoelectrochemical Water Splitting

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CuO/NiOx thin film–based photocathodes for photoelectrochemical water splitting

Cited by 40 publications

References 45 publications

Approaches for Modifying Oxide-Semiconductor Materials to Increase the Efficiency of Photocatalytic Water Splitting

Approaches for Modifying Oxide-Semiconductor Materials to Increase the Efficiency of Photocatalytic Water Splitting

Effect of Co-catalyst (CuO, CoO or NiO) on Bi2O3–TiO2 Structures and Its Impact on the Photocatalytic Reduction of 4-nitrophenol

Cu2O/ZnO p–n Junction Decorated with NiOx as a Protective Layer and Cocatalyst for Enhanced Photoelectrochemical Water Splitting

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Cu₂O/ZnO p–n Junction Decorated with NiO_x as a Protective Layer and Cocatalyst for Enhanced Photoelectrochemical Water Splitting