Enhancement of Photocatalytic Activity of Electrodeposited Cu₂O by Reducing Oxygen Vacancy Density

Abstract

Oxygen vacancies (OVs) are common in cuprous oxide (Cu2O), and the effect of OVs on photocatalytic activity remains unclear. In this study, the photocatalytic activity of Cu2O photoanode with varying OV densities was investigated. The OV density in Cu2O was controlled by adjusting the Cu(CH3COO)2 concentration in a precursor solution used for the electrodeposition of Cu2O. The oxygen deficiency decreased from 5.2 to 0.4%, characterized through X-ray diffraction, when the Cu(CH3COO)2 concentration was reduced from 0.04 to 0.005 M due to the decrease in the mismatch between the concentrations of Cu(CH3COO)2 and OH–. The decrease in the OV density increased the excess photocharge density of Cu2O, as verified by photoluminescence and photovoltage measurements. Furthermore, the decrease in the OV density resulted in the enhancement of the spectral response and photocatalytic activity; this was attributed to the increase in the excess photocharge density. OVs in Cu2O mainly mediated the photocharge recombination and played a negative role in photocatalytic activity.

Optimization of Cu2O Thickness to Enhance Photocatalytic Properties of Electrodeposited Cu2O/FTO Photoanode

“…Cu2O film was fabricated using the electrochemical deposition method in a threeelectrode cell using an electrochemical workstation (Zahner Zennium, Germany) [12]. The working electrode was FTO, the reference electrode was Ag/AgCl, and the counter electrode was a Pt plate.…”

“…The p-type Cu2O acts as a photocathode used for photocatalytic reduction reactions [8,9]. Currently, many researchers prepared Cu2O as an n-type semiconductor, which is formed due to oxygen vacancies [10][11][12]. The n-type Cu2O acts as photoanode and is applied for photocatalytic oxidation reactions [11,12].…”

“…Currently, many researchers prepared Cu2O as an n-type semiconductor, which is formed due to oxygen vacancies [10][11][12]. The n-type Cu2O acts as photoanode and is applied for photocatalytic oxidation reactions [11,12]. The n-type Cu2O is interesting to study widely because of its application for photocatalytic degradation of dyes that pollute the environment.…”

“…Furthermore, the variation of deposition time can change the morphology and thickness of n-type Cu2O [18]. Several works have attempted to enhance the photocatalytic performance of n-type Cu2O by changing the deposition parameters in the electrochemical deposition method [10][11][12]19]. As a photoelectrode, thickness of Cu2O film can affect the photon absorption and charge diffusion, where the increase of film thickness can increase the light absorption, but reduce the charge diffusion [20].…”

Understanding the role of oxygen-vacancy defects in Cu2O(111) from first-principle calculations

“…Current experimental findings will be explained by an insightful knowledge of the function of V O , which may be seen theoretically by considering how it operates in semiconductor devices or catalytic reactions situated on the surface or interface of Cu 2 O. It is crucial for further advancements in abundant Cu 2 O-based materials, particularly for the development of p-n heterojunctions for Cu 2 O-based photovoltaic devices [24] and the adsorption and dissociation of gases (O 2 [26], NO [27], CS 2 [28] etc) On photocatalysis, Khasanah et al [29] pointed out that the dominating effect of V O in Cu 2 O remains to be determined, because it exerts opposite effects by facilitating the photocharge recombination and reducing the high reaction overpotential at the interface. Further, Kumar et al [30] demonstrate that due to the suitable band gap, Cu 2 O are widely employed as the photocathode and the photoanode in photoelectrochemical water splitting, and enhance its productivity by tuning nanostructures, such as by introducing defects or dopants.…”