Photo-electrocatalytic H2 evolution on poly(2,2′-bithiophene) at neutral pH

Vapour phase polymerised (VPP) polybithiophene (PBTh) on glassy carbon is revealed to be an efficient photo-electrocatalytic electrode for the hydrogen evolution reaction (HER). An onset potential of −0.03 V vs SCE for the HER is observed on illumination using visible light in 0.1 mol L−1 phosphate buffer at pH 6.9, 600 mV lower in energy than E0. Hydrogen evolution is confirmed using gas chromatography with a calculated faradaic efficiency of 34% when holding at a potential of −0.5 V. Importantly, this process occurs without platinum and under neutral aqueous conditions thus revealing a significant but overlooked application for PBTh: a potential low-cost cathode material for the splitting of water.