Enhanced Hydrogen Evolution under Simulated Sunlight from Neutral Electrolytes on (ZnSe)0.85(CuIn0.7Ga0.3Se2)0.15 Photocathodes Prepared by a Bilayer Method

A (ZnSe)(0.85)(CuIn0.7Ga0.3Se2)(0.15) photocathode with a bilayer structure was fabricated and found to exhibit a photocurrent almost twice that of a photocathode with a monolayer structure during hydrogen evolution from water. The cathodic photocurrent reached maximum values of 12 and 4.9mAcm(-2) at 0 and 0.6V(RHE) in a neutral phosphate buffer under simulated sunlight, while the half-cell solar-to-hydrogen conversion efficiency was 3.0% at 0.6V(RHE), with a maximum value of 3.6% at 0.45V(RHE). Cross-sectional mapping of the electron-beam-induced current established that the increased photocurrent can be attributed to improved uniformity at the solid-liquid junction in the bilayer sample, which results in enhanced carrier collection.