Hydrogen evolution from solar water splitting on nanostructured copper oxide photocathodes

Abstract

Copper oxide has received much attention as a photocatalyst for solar water splitting, since it has a band gap of ∼2.0 eV with favourable energy band positions for water cleavage; it is abundant and environmentally friendly. In this paper, we report the preparation of copper oxide thin films on copper substrate with different morphology by a solution route in large scales. The method was simple, low cost, and can be completed in the absence of any surfactant. Copper oxide films were characterised by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Fourier transform-infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The XRD analysis and FT-IR analysis confirm the formation of copper oxide films. SEM images show gradual development of hierarchical structures of copper oxide with different morphology. The films were successfully tested as photocathodes in a photoelectrochemical cell, and their photocatalytic activity was evaluated by testing the solar water splitting. The photocatalytic activity of these films was found to be size-dependent and films with smaller dimensions demonstrated a significant increase in photocatalytic activities during solar water splitting process. Based on the above discussion, we believe that these samples are attractive candidates as a visible-light-driven photocatalyst.

Iron oxide nanostructures for photoelectrochemical applications: Effect of applied potential during Fe anodization

“…Since Fujishima and Honda in 1972 reported the study of TiO2 nanostructures for photoectrochemical water splitting [19], nanostructures of different oxide metals (TiO2, Fe2O3, WO3, CuO, SnO2, etc.) have been widely studied for the same purpose [11,[20][21][22]. This is due to the fact that nanostructures provide high surface area and reactive sites, and they also promote charge separation and transport of charge carriers [23,24].…”

On the structural evolution of nanoporous optically transparent CuO photocathodes upon calcination for photoelectrochemical applications

“…40,41 Regarding nanostructuring of CuO photoabsorbers, decreasing the size of structural features, such as the crystallite size, and forming porous structures was claimed to improve the photoelectrochemical performance due to increased surface areas and, consequently, more reaction sites for the solar-driven hydrogen evolution reaction. [42][43][44] Even though nanostructuring seems to help suppress photocorrosion, about 55% of the photocurrent still has been assigned to reduction of copper ions to metallic copper, 45 emphasizing the demand for a detailed analysis and optimization of the CuO (nano-) morphology and electronic structure. In this context, the Bein group has intensively investigated the photostability of CuO photocathodes, achieving a faradaic hydrogen production efficiency of 91% over 15 minutes through improvement of the PEC properties by Li doping and deposition of a 2.5 nm Ti 0.8 Nb 0.2 O x protection layer.…”