Bi-functional electrochemical water splitting performance of the BiOCl electrocatalysts

Abstract

In this study, effect of air annealing temperatures on electrocatalytic water splitting performance of the bismuth oxy-chloride (BiOCl) is investigated and explored. The BiOCl catalyst is chemically synthesized initially which is further air annealed at different temperatures viz., 50 degrees C, 150 degrees C, 300 degrees C, and 600 degrees C for knowing changes in the structure, surface morphology and electrochemical properties. The electrocatalytic activities like hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are systematically evaluated in alkaline medium where air annealing temperature has significant influence on the catalytic performance of the BiOCl. Along with excellent stability for prolonged electrolysis, the one annealed at 150 degrees C demonstrates a superior electrocatalytic activity having; low overpotentials of 286 mV for OER and 223 mV for HER at a current density of 10 mA/cm2, Tafel slopes of 114 mV/dec for OER and 106 mV/dec for HER than pristine and higher temperature annealed BiOCl catalysts. The enhanced catalytic performance of the 150 degrees C-annealed BiOCl catalyst is attributed to its improved crystallinity and unique surface morphology with reduced charge transfer resistance.