Enhancement of Solar Hydrogen Evolution from Water by Surface Modification with CdS and TiO ₂ on Porous CuInS ₂ Photocathodes Prepared by an Electrodeposition–Sulfurization Method

Porous films of p-type CuInS2, prepared by sulfurization of electrodeposited metals, are surface-modified with thin layers of CdS and TiO2. This specific porous electrode evolved H2 from photoelectrochemical water reduction under simulated sunlight. Modification with thin n-type CdS and TiO2 layers significantly increased the cathodic photocurrent and onset potential through the formation of a p-n junction on the surface. The modified photocathodes showed a relatively high efficiency and stable H2 production under the present reaction conditions.