Improving the Stability and Efficiency of CuO Photocathodes for Solar Hydrogen Production through Modification with Iron

Abstract

Cupric oxide (CuO) is considered as a promising photocathode material for photo(electro)chemical water splitting because of its suitable band gap, low cost related to copper earth abundancy, and straightforward fabrication. The main challenge for the development of practical CuO-based photocathodes for solar hydrogen evolution is to enhance its stability against photocorrosion. In this work, stable and efficient CuO photocathodes have been developed by using a simple and cost-effective methodology. CuO films, composed of nanowires and prepared by chemical oxidation of electrodeposited Cu, develop relatively high photocurrents in 1 M NaOH. However, this photocurrent appears to be partly associated with photocorrosion of CuO. It is significant though that, even unprotected, a faradaic efficiency for hydrogen evolution of ∼45% is attained. The incorporation of iron through an impregnation method, followed by a high-temperature thermal treatment for promoting the external phase transition of the nanowires from CuO to ternary copper iron oxide, was found to provide an improved stability at the expense of photocurrent, which decreases to about one-third of its initial value. In contrast, a faradaic efficiency for hydrogen evolution of ∼100% is achieved even in the absence of co-catalysts, which is ascribable to the favorable band positions of CuO and the iron copper ternary oxide in the core-shell structure of the nanowires.

Enhanced Photoelectrochemical Water Splitting at Hematite Photoanodes by Effect of a NiFe-Oxide co-Catalyst

“…Fe 2 O 3 and CuO, which were previously studied separately for O 2 and H 2 generation, respectively, showing high photoresponses [11][12][13][14][15], were deposited onto transparent fluorine-doped tin oxide (FTO) glasses. Among the large number of semiconductor materials actively investigated as candidates for the OER [16][17][18][19][20], n-type hematite (n-Fe 2 O 3 ) is widely employed as a photoanode according to several advantages such as its low cost, suitable stability and favourable band gap and band level positions in relation to the reversible potential for oxygen evolution [21,22].…”

Porous Cupric Oxide: Efficient Photocathode for Photoelectrochemical Water Splitting

“…Cots et al. have modified the surface of CuO nanowire with a ternary oxide layer of CuFe 2 O 4 which helps to improve the stability of the developed CuO . Engineering in the morphology can shorten the traveling path of minority carrier which further helps to enhance the photoelectrochemical activity of the material.…”

Photoelectrochemical CO2 Reduction via Cu2O/CuFeO2 Hierarchical nanorods photocatalyst

“…[6,10] According to several reported studies, Cu 2 O photocathodes that are not nanostructured exhibit low performance. [19,35] To improve the performance of the photoelectrode, the following problems must be solved by nanostructuring the photoelectrode. First, the short diffusion length of the minority carrier needs to be solved.…”