A SrTiO^sub 3^-TiO^sub 2^ eutectic composite as a stable photoanode material for photoelectrochemical hydrogen production

Semiconductors with band-gap energy levels corresponding to the solar energy spectrum are thought to have great potential for use as electrodes to produce hydrogen in photoelectrochemical (PEC) cells. However, many electrode designs suffer from either poor stability or low energy conversion efficiency, which have limited commercialization. Here, we demonstrate a PEC cell that uses a durable eutectic system consisting of titanium dioxide and strontium titanate as the active photoanode material, with very good transport properties due to its high crystallinity. The semiconductor composite yielded photocurrents up to 8.5 mA/cm2 at 1.5 V vs. a normal hydrogen electrode (NHE), after 30 h of stability testing under 600 mW/cm2 of solar irradiation to boost potential photocorrosion. This performance is competitive with that reported for other state-of-the-art systems comprising titanium dioxide and strontium titanate. Transmission-spectroscopy measurements and three-dimensional profilometry revealed a decreased reflectance by 50% and an increased surface area of the electrode over the 30 h of analysis, underlying the enhanced photocurrent in our PEC cell. Further electrode optimization will yield additional improvements in the energy conversion efficiency, i.e. by cocatalyst loading, composite with anatase phase instead of rutile phase, or coupling with organic dyes.