Stable hydrogen generation from Ni- and Co-based co-catalysts in supported CdS PEC cell†
To improve the limited efficiency and stability of CdS photoanodes in a photoelectrochemical (PEC) cell, the nanostructured CdS photoanode was modified with Ni(OH)2, NiO, Co(OH)2, and Co3O4 water-oxidation-nano co-catalysts (WOC). Co(OH)2 nanorice and Ni(OH)2 nanosheet co-catalysts were obtained by a simple chemical precipitation method. Modification by the co-catalysts gives longer stability (>8 h) to CdS electrodes, and facilitates impulsive H2 evolution in PEC cells. Nano-NiO modification yields a two-fold increase in photocurrent density and the highest H2 evolution of 2.5 mmol h−1. A dual role for Ni related co-catalysts over CdS surface, that is forming a p–n junction and acting as an effective co-catalyst, improves the photocurrent and hydrogen evolution rate, respectively. Improvement in stability was measured using X-ray photoelectron spectroscopy and prolong chronoamperometry measurements. The present report focuses on exploration of chemically synthesized earth-abundant and cost-effective co-catalysts for PEC H2 generation.