Electrochemical nano-patterning of brass for stable and visible light-induced photoelectrochemical water splitting

A novel propitious nano-patterned brass oxide nanowires were fabricated via controlled anodization of α-brass in aqueous electrolytes at room temperature. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS) techniques were used to investigate the morphology, structure, and composition of the fabricated materials. The morphology of the resulted structures was found to depend on the concentration of the sodium bicarbonate used for anodization as well as the post treatment. The XRD analysis confirmed the existence of both ZnO and CuO. The XPS results suggest the formation of CuZnO nanowires. The fabricated nanowires showed exceptional optical activity with an absorption wavelength extending to 800 nm, corresponding to a bandgap energy of 1.7 eV. This bandgap energy was also confirmed via DFT calculations. The fabricated nanostructures were used to split water photoelectrochemically under AM 1.5 illumination. They showed very promising results towards visible light water splitting with a photocurrent of 1.88 mA/cm 2 at −0.5 V versus Ag/AgCl, an incident photon-to-current efficiency (IPCE) of ∼15% at 400 nm, and a production of ∼875 μmol of H 2 gas upon illumination for 5 h. The obtained photocurrent is at least five times higher than that reported for ZnO and TiO 2. The transient photocurrent measurements showed the fabricated electrode to be photostable under the operating conditions.