Improved Efficiency of Photoelectrochemical Water Oxidation using Tin Disulfide Photoanodes.

Tin disulfide (SnS$_{\mathrm{2}})$ has gained a lot of attention from the scientific community due to its unique electrical and optical properties, which make it suitable for photocatalysis and solar energy conversion. It has a high absorption coefficient and can be used in photovoltaics as a single junction solar cell or in tandem with other materials such as silicon. When SnS$_{\mathrm{2}}$ thin films are used in tandem with silicon, the overall theoretical efficiency can surpass Shockley-Queisser limit of silicon. SnS$_{\mathrm{2}}$ is also a suitable material for photoelectrochemical (PEC) water oxidation because its conduction and valence band edges straddle redox potential of water. We report a scalable method of synthesizing thin films of tin disulfide nanoflakes in a two-step process. In the first step, pure SnS$_{\mathrm{2}}$ powder is synthesized using hydrothermal method. This powder is then evaporated in a vacuum environment and coated on conductive substrates. Although SnS$_{\mathrm{2\thinspace }}$has been fabricated before, this is the first project in which significant photocurrent has been recorded using SnS$_{\mathrm{2}}$ photoanode. We report photocurrents up to 2.6mA/cm$^{\mathrm{2}}$ achieved at 1.23 V vs RHE from a SnS$_{\mathrm{2}}$ photoanode when illuminated with a Xenon Lamp (300W, 100mW/cm$^{\mathrm{2}})$.