Stable hydrogen generation from Ni- and Co-based co-catalysts in supported CdS PEC cell

Abstract

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.