The optimum PC powder loading of SVG-PC for both water splitting and water purification was found to be 2.0 mg cm -2 (Fig. , Supplementary Discussion 2). With this loading, the obtained vapour generation rate of 0.95±0.10 kg m -2 h -1 (equating to ~53 molvapour m -2 h -1 ) agrees well with reported literature values for carbonaceous SVGs (Fig. , Supplementary Tables ). The rate of vapour production via SVG is in excess as theoretically required for sustaining the overall water splitting reaction carried out by RhCrOx-Al:SrTiO3, which requires three orders of magnitude less water than the current SVG output and the excess water vapour produces distilled water. 26