Glycine-nitrate derived cobalt-doped BiPO4: An efficient OER catalyst for alkaline electrochemical cells

Abstract

The investigation of cost effective and earth abundant electro-catalyst to catalyze oxygen evolution reaction (OER) is highly desirable for the development of future sustainable energy. Herein, a facile one step glycine-nitrate decomposition method has been proposed to synthesize crystalline un-doped and cobalt doped BiPO4. The prepared un-doped and cobalt doped BiPO4 have been evaluated as potential electro-catalysts for OER. The XRD, XPS and ICP-OES results reveal that BiPO4 undergo surface reconstruction during OER and thereby converted into Bi2O3. Thus, the in situ formed Bi2O3 is the real active catalyst to catalyze OER where 5% cobalt doped BiPO4 exhibits excellent OER activity in terms of low overpotential of 328 mV and 394 mV to afford the current density of 10 and 50 mA cm−2 respectively, which is much lower than that of the un-doped BiPO4 (480 mV). Besides, the polarization curves of 5% cobalt doped BiPO4 shows negligible difference in overpotential even after 20 h of continuous electrolysis, demonstrating excellent stability in alkaline KOH. This work demonstrates intrinsic electro-catalytic activity of phosphate based electro-catalyst can be improved by doping with suitable transition metal and through surface reconstruction.