Enhanced Visible-Light Photoactivity of CuWO₄ through a Surface-Deposited CuO

Abstract

Several papers have shown that CuWO 4 is active under visible light for water oxidation at an applied potential bias and for organic degradation in an aerated aqueous suspension. In this work, we report that the observed reduction of O 2 on the irradiated CuWO 4 is a multielectron transfer process with the formation of H 2 O 2 . More importantly, the surface modification of CuWO 4 with 1.8 wt % of CuO can increase the activity by approximately 9 times under UV light and by 5 times under visible light, for phenol degradation in aerated aqueous suspension. The catalyst was prepared by a hydrothermal reaction between Cu(NO 3 ) 2 and Na 2 WO 4 , followed by thermal treatment at 773 K. High-resolution transmission electron microscopy revealed that triclinic CuWO 4 (40 nm) was covered by monoclinic CuO (4 nm). Through a combination of photo-and electrochemical measurement, a plausible mechanism responsible for the activity enhancement is proposed, involving an interfacial electron transfer from CuO to CuWO 4 and an interfacial hole transfer from CuWO 4 to CuO.

Preparation of Bifunctional CuWO4‐Based Heterostructure Nanocomposites for Noble‐Metal‐Free Photocatalysts

“…It was found to be 0.136, 0.071, 0.577, 0.124, 0.125, 0.235 and 0.125 V vs RHE for (700 °C) and (800 °C) respectively. The obtained of is almost similar with fractional varation incorparation to the early reported value, due to pH of the electrolyte solution . Then, the shifted to the lower value by the formation of other secondary phase, particularly the samples with low were showed better photocatalytic degradation under illumination.…”

“…Figure describes the schematic representation for oxidation of the nanocomposites. The and have showed photocathodic current, it may be due to p ‐type nature of and CuO . To best of our knowledge, we present the PEC performance first time for and nanocomposites.…”

“…The V fb was determined using the equation [54] due to pH of the electrolyte solution. [55] Then, the V fb shifted to the lower value by the formation of other secondary phase, particularly the samples with low V fb were showed better photocatalytic degradation under illumination.…”

Promotion of multi-electron transfer for enhanced photocatalysis: A review focused on oxygen reduction reaction

“…[47][48][49] Although the value of E CB of CuO is usually more negative than that of single oxygen reduction, it shows an abnormal behavior of two-electron reduction ability of oxygen. Bandara et al [50] showed that CuO was able to produce H 2 O 2 under sunlight irradiation at room temperature, which was Accordingly, the storing of O 2 as H 2 O 2 via double-electron reduction process would proceed by the following reactions:…”

“…They investigated the oxygen reduction reaction over In fact, multi-electron ORR is also observed in other type II heterojunction. Chen et al [79] have prepared CuWO 4 /CuO composites via hydrothermal reaction, followed by thermal treatment. Photocatalytic test showed that the surface modification of Besides type II heterojunction based metal oxides, Katsumata et al [80] have prepared g-C 3 N 4 /WO 3 composites photocatalyst and evaluated their activity via acetaldehyde degradation.…”