Solar Energy & Advanced Materials Research Group


New Paper in Appl. Catal. B

1 October 2020

A new paper by Chaoran et al. just published in Applied Catalysis B: Environmental.

Our new paper on the investigation of Co3+ - O - V4+ cluster in CoVOx nanorods for efficient and stable electrochemical oxygen evolution just published in Appl. Catal. B! Big congratulations to Chaoran!

Chaoran found a higher ratio of V4+/V5+ is favourable to stabilize a high concentration of Co3+ on the surface, which is for the first time reported. The extremely high Co3+/Co2+ ratio results to a 20 time higher current than the reported active CoOx-300 and 1000 times higher than VOx-300. The surface Co3+-O-V4+ cluster lowers apparent activation energy, accelerating the OER kinetics and improve the overall performance. The overall performance is comparable to the commercial benchmark catalyst based on precious metal RuO2.

The development of cost-efficient and long-term stable catalysts for the oxygen evolution reaction (OER) is crucial to produce clean and sustainable H2 fuels from water. Here we demonstrate a cobalt vanadium oxide (CoVOx-300) working as such an efficient and durable electrocatalyst. Such an active catalyst is beneficial from the balanced Co3+-O-V4+ active species, which show the high surface Co3+ contents with matched V4+ generated by rapid heat treatment. The CoVOx-300 with highest Co3+/Co2+ ratio of 1.4 and corresponding highest V4+/ V5+ ratio of 1.7 exhibits remarkable OER activity with an overpotential of 330 mV at current density of 10 mA cm−2 (η10), a shallow Tafel slope of only 46 mV dec-1 and a current density of 100 mA cm−2 at an overpotential of 0.38 V vs RHE, which is 20 times higher than the active CoOx-300 and 1000 times higher than VOx-300. The catalyst also shows excellent stability for 10 h in alkaline media and a 40 % reduced activation energy to the counterpart, CoOx-300. The overpotential (η10) of CoVOx-300 also shows nearly 70 and 80 mV lower than the corresponding CoOx-300 and CoVOx catalysts, respectively and 20 % lower Tafel slope than the commercial benchmark catalyst RuO2. Thus, this study for the first time demonstrates that surface Co3+-O-V4+ species play a crucial role in improving electrocatalytic properties and stability for water oxidation reaction and the approaches allow the rational design and synthesis of other active transition metal oxides toward efficient OER activity.