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

An efficient, stable, and intrinsically safe solar water-splitting device is demonstrated using a III–V tandem junction photoanode, an acid-stable, earth-abundant hydrogen evolution catalyst, and a bipolar membrane. The integrated photoelectrochemical cell operates under a steady-state pH gradient and achieves ≈10% solar-to-hydrogen conversion efficiency, >100 h of stability in a large (>1 cm2) photoactive area in relation to most previous reports.