Stable Hydrogen Evolution from an AgRhO₂ Photocathode under Visible Light

In the search for improved materials for photoelectrochemical water splitting, it has become important to identify new classes of semiconductor materials that may serve as improved photocathodes. To this end, p-type AgRhO₂ has been synthesized and tested as a photocathode for water splitting. The AgRhO₂ photocathode is found to exhibit excellent photocatalytic capability for reducing protons to H₂ across a wide range of pH values with nearly 100% faradaic efficiency and good photostability. Polycrystalline AgRhO₂ electrodes exhibit strong preferred c-axis orientation, resulting in anisotropic conductivity, evident from resistivity measurements. AgRhO₂ photocathodes are found to provide improved performance and photostability when compared to prior work using a p-CuRhO₂ electrode. Enhanced performance is in part attributed to the unusual degree of c-axis orientation found in this material. In addition, there is a significantly lower kinetic barrier for H₂ production at the AgRhO₂ interface.