V3+ Incorporated β-Co(OH)2: A Robust and Efficient Electrocatalyst for Water Oxidation

Catalyzing oxygen evolution reaction (OER) with the lowest possible overpotential is a key to ensure energy efficiency in the production of hydrogen from water electrochemically. In this report, we show the results that astonished us. Co hydroxide containing trivalent V was prepared chemically and screened for electrochemical water oxidation in rigorously Fe free 1 M KOH (pH 13.8). Overpotential of 198 mV at 10 mA cm–2 was observed for the synthesized Co–V hydroxide with the optimal Tafel slope of 60 mV dec–1. This is the lowest overpotential at this current density ever reported for OER in alkaline conditions while utilizing Co based electrocatalysts. Density function theory (DFT) calculations showed that the third elementary step (oxyhydroxide formation and delivery of O2) was spontaneous on V site that is bridging two adjacent Co sites which was attributed to the observed enhancement.