A Stabilized, Intrinsically Safe, 10% Efficient, Solar-Driven Water-Splitting Cell Incorporating Earth-Abundant Electrocatalysts with Steady-State pH Gradients and Product Separation Enabled by a Bipolar Membrane

Unassisted, intrinsically safe, solar-driven water splitting was demonstrated using a tandem photoelctrode and a bipolar membrane that allowed maintaining the anolyte at pH 9.3 and the catholyte at pH 0. The water splitting efficiency displayed by the BPM-incorporated photoelectrochemical cell was equivalent to the use of a photovoltaic cell with a nefficiency of 16% in series with an efficient electrolyzer unit. The bipolar membrane prevented product gas crossover and partly impeded ion crossover during steady-state operation. Implementation of the BPM led to an enhancement in the stability of the photoanode due to operation under passivating conditions, and enabled operation of a cell without the need to fi nd a stable, active oxygen evolution catalyst catalyst in acidic electrolytes.