Cobalt doping in tantalum nitride thin films prepared by sputtering

![CDATA[The process of solar driven water splitting, employed in theoretical solar hydrogen farms, could provide sustainable hydrogen in a theoretical hydrogen economy. Since the discovery of photocatalytic water splitting using TiO2, four decades of research has been focused on the development of efficient solar to hydrogen water splitting materials. In recent years, various nitride materials have been highlighted as possessing great potential for efficient water splitting. Tantalum nitride, specifically Ta3N5, is one such nitride, possessing appropriate band edge positions for efficient, bias free overall water splitting and a band gap allowing absorption of visible light. The goal of this study was to evaluate the impact of cobalt doping on Ta3N5, for ultimate use as a photo-electrode. Doping is one of many approaches have been utilised to optimise the properties of Ta3N5 for solar water splitting, with the inclusion of metals such as Zr and Mg (among others) having been shown to improve the crystallisation of Ta3N5, confer band gap control or improve conductivity. Cobalt is a heavily studied dopant species in semiconductors and was selected for this study due to its abundance of electronic states and potential to improve favourable defects in the Ta3N5 lattice. Given the relatively immature nature of doped Ta3N5 in the literature, it is important to characterise the impact of dopants on the host structure.]]