Sol–gel deposited Cu₂O and CuO thin films for photocatalytic water splitting

Abstract

Cu2O and CuO are attractive photocatalytic materials for water splitting due to their earth abundance and low cost. In this paper, we report the deposition of Cu2O and CuO thin films by a sol-gel spin-coating process. Sol-gel deposition has distinctive advantages such as low-cost solution processing and uniform film formation over large areas with a precise stoichiometry and thickness control. Pure-phase Cu2O and CuO films were obtained by thermal annealing at 500 °C in nitrogen and ambient air, respectively. The films were successfully incorporated as photocathodes in a photoelectrochemical (PEC) cell, achieving photocurrents of -0.28 mA cm(-2) and -0.35 mA cm(-2) (for Cu2O and CuO, respectively) at 0.05 V vs. a reversible hydrogen electrode (RHE). The Cu2O photocurrent was enhanced to -0.47 mA cm(-2) upon incorporation of a thin layer of a NiOx co-catalyst. Preliminary stability studies indicate that CuO may be more stable than Cu2O as a photocathode for PEC water-splitting.

Effect of Deposition Time on the Photoelectrochemical Properties of Cupric Oxide Thin Films Synthesized via Electrodeposition Method

“…As the CuO film thickness increases, more light can be absorbed until a certain thickness, whereby the CuO films will reduce the light photon penetration. This will increase the electron-hole pair recombination rate and results in a lower water-to-hydrogen conversion efficiency [4]. From Figure 5, it was found that the photocurrent density increased with increasing CuO nanocrystals size.…”

“…Lim et al [4] studied the deposition of Cu 2 O and CuO thin films by a sol-gel spin-coating process, and enhanced the PEC performance by depositing a thin layer of NiO x co-catalyst. Wang et al [6] investigated the effect of deposition voltage on the morphology of CuO thin films.…”

“…Binary copper semiconductors have attracted much research interests owing to their high photoactivity, inexpensive and that copper is a relatively abundant element [2]. Cupric oxide (CuO) is one of the p-type binary copper semiconductors with a narrow bandgap of 1.3 to 1.9 eV, and a corresponding theoretical photocurrent density of 35 mA/cm 2 [3,4].…”

Ion implantation induced phase transformation and enhanced crystallinity of as deposited copper oxide thin films by pulsed laser deposition

“…The slope increased with the particles fluence, indicating that the lowest resistance corresponded to the batch implanted with 4 Â 10 16 particles/cm 2 . The observed decrease in the resistance can be attributed to two phenomenon (a) increase in the dopant concentration doe to increase in the fluence and (b) transformation of Cu 2 O phase to a CuO phase which exhibits higher electrical conductivity than Cu 2 O [37]. From these results, it may be surmised that the optical and the XRD studies were significant to understand the effect of low energy ion implantation as a post depositional method on the copper oxide thin film deposited by PLD technique.…”

Enhanced visible-light activities for PEC water reduction of CuO nanoplates by coupling with anatase TiO2 and mechanism

“…Constructing junctions is a common and effective way to promote charge separation and prolong charge carriers lifetimes [11]. Recently several new related works pointed out that the property of CuO can be improved by modifying Ag [12] nanoparticless or Cu 2 O [13]. These strategies are regarded to improve the light harvesting ability to enhance the photocatalytic activities.…”