Cu@Cu 2 O films were prepared by electrochemical deposition method. The obtained Cu@Cu 2 O films were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), confocal Raman spectroscopy (CRS), UV–visible absorption spectroscopy and Photoluminescence (PL) spectroscopy. Electrochemical measurements were performed under intermittent visible light illumination to assess the photoelectrochemical cathodic protection effect of the prepared Cu@Cu 2 O films. The results indicated that a lower deposition potential could facilitate the reduction of Cu 2 O grain size together with an increase number of Cu. But the deposition potential has no obvious influence on the band-gap of the composite films, which exhibited n-type semiconductor properties. The open circuit potential of 304 stainless steel by coupling with the Cu@Cu 2 O-0.3 V films presented the most negative shift of −179 mV under visible-light illumination. The related photocurrent density was 0.13 mA·cm −2 . The photoelectrochemical conversion mechanism and the photoelectrochemical cathodic protection effects of the Cu@Cu 2 O films were discussed in detail.
Cu 2 O films were prepared using an improved solution immersion method, whereas ZnO/Cu 2 O films were prepared using an electrodeposition method. Then, the pure Cu 2 O film electrodes and ZnO/Cu 2 O film electrodes were used to reduce CO 2 to CH 3 OH. The crystal structure, morphology, particle size, and specific surface area of pure Cu 2 O films prepared under different immersion times and ZnO/Cu 2 O films prepared under different deposition times and Zn 2+ concentrations were analyzed using X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. The electrolytic activity of the pure Cu 2 O film electrodes and ZnO/Cu 2 O film electrodes were studied. Under the same reaction conditions, the ZnO/Cu 2 O film electrode with the Zn 2+ concentration of 0.05 M and the deposition time of 30 min had the highest total CH 3 OH yield of 315.656 μmol/cm 2 and the fastest formation rate of 52.609 μmol/(cm 2 h), and its faradaic efficiency was 45%, which was remarkably higher than that of pure Cu 2 O film electrodes under the same reaction conditions. This study highlighted that ZnO nanoparticles had a very good promotion of electrolytic CO 2 reduction on Cu 2 O film.
Hao Yuliang,Zuo Xiaolei,Zhao Weiyi,Wu Jichuan,lin Xiaoqiang,Wang Hongyan,Wang Zeshan,Hao Chuanxiang,Xue Song
Cuprous oxide (Cu 2 O) is a highly promising photocatalyst that facilitates efficient water splitting and hydrogen production under light conditions. In this study, Cu 2 O thin film photocathodes were prepared through electro-deposition, with the inclusion of \(\mathrm{NO}^{-}_{3}\) ions resulting in the formation of a flower-like microstructure. The size, distribution and roughness of these clusters were found to be greatly influenced by the concentration of the \(\mathrm{NO}^{-}_{3}\) ions as confirmed by SEM and AFM characterizations. When 0.4 M \(\mathrm{NO}^{-}_{3}\) ions were used, a flat and compact structure with the smallest ‘flower bud’ was obtained. This structure achieved a maximum photocurrent density of − 2.90 mA/cm 2 @0 V vs. RHE, which is 2.2 times greater than that of bare Cu 2 O. UV–Vis absorption, steady-state fluorescence spectroscopy and EIS measurements suggest that the compact microstructure facilitates enhanced ultraviolet absorption and separation of photogenerated holes and electrons. This results in a lower charge transfer resistance and a significant increase in photocurrent density. Additionally, a growth mechanism for the flower-like Cu 2 O was proposed. The XPS and EDS analyses indicate that the addition of \(\mathrm{NO}^{-}_{3}\) during Cu 2 O formation results in the adsorption of \(\mathrm{NO}^{-}_{3}\) onto the surface of the initial Cu 2 O grain. This, in turn, catalyses the electrocatalytic reduction of \(\mathrm{NO}^{-}_{3}\) on the surface of Cu 2 O, leading to the formation of NH + 4 ions as evidenced by XPS.
Ping Qiu,Yongyong Lai,Xulu Sun,Changfeng Chen,Lei Ge
Various approaches have been developed to enhance n-type Cu 2 O photoelectrochemical activity. This study introduced a simple method of tuning electronic structure through adjusting solution pH when electrodeposition of Cu 2 O films on FTO substrate. Combined surface analysis showed that the Cu 2 O films presented gradual change cruciate flower-like nanostructure and hybrided with metallic copper. The Cu/Cu 2 O films presented a visible light response and the band gap could be effectively decreased by increasing the deposition solution pH. The photoelectrochemical cathodic protection performance of the films was studied. The electrode potential of 304 stainless steel by coupling with the Cu/Cu 2 O films (deposited at pH 5) reached the most negative photopotential shift of 179 mV under illumination. The related photocurrent density was 0.12 mA/cm 2 . This enhanced photoelectrochemical performance was evidenced by both direct excitation of Cu 2 O and the surface plasmon resonance effects of Cu upon illumination.
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