Bifunctional Catalyst Derived from Sulfur-Doped VMoO_x Nanolayer Shelled Co Nanosheets for Efficient Water Splitting

A novel sulfur-doped vanadium–molybdenum oxide nanolayer shelling over two-dimensional cobalt nanosheets (2D Co@S-VMoOx NSs) was synthesized via a facile approach. The formation of such a unique 2D core@shell structure together with unusual sulfur doping effect increased the electrochemically active surface area and provided excellent electric conductivity, thereby boosting the activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As a result, only low overpotentials of 73 and 274 mV were required to achieve a current response of 10 mA cm–2 toward HER and OER, respectively. Using the 2D Co@S-VMoOx NSs on nickel foam as both cathode and anode electrode, the fabricated electrolyzer showed superior performance with a small cell voltage of 1.55 V at 10 mA cm–2 and excellent stability. These results suggested that the 2D Co@S-VMoOx NSs material might be a potential bifunctional catalyst for green hydrogen production via electrochemical water splitting.