Co<sub>3</sub>O<sub>4</sub> Nanocube-Templated CoS<sub>2</sub> and CoS<sub>2</sub>/MoS<sub>2</sub> Heterostructures for Multifunctional Electrocatalysis
Ayan Mondal, Harish Reddy Inta, Avishek Roy, Ashok Kumar Mahato, Venkataramanan Mahalingam
Abstract
The design and development of efficient and low-cost electrocatalysts for both anodic (oxygen evolution reaction (OER)/hydrazine oxidation reaction (HzOR)) and cathodic (hydrogen evolution reaction (HER)) reactions are the major challenges for cleaner hydrogen production. Especially, the fabrication of electrocatalysts with abundant electrochemically active sites through simple synthetic routes is of great interest to draw excellent catalytic efficiency. This report provides a strategy to prepare CoS 2 –MoS 2 heterostructures and spheroid-like CoS 2 through the sulfurization reaction from the common Co 3 O 4 nanocube precursor in the presence and absence of the molybdenum precursor, respectively. The as-prepared CoS 2 –MoS 2 (25) heterostructure (prepared with 25 mg of Co 3 O 4 ) shows excellent HER activity in 1 M KOH by delivering a current density of 10 mA/cm geo 2 at an overpotential of 92.5 ± 3.1 mV. The observed enhancement in the HER activity is attributed to the improved water dissociation kinetics at the abundant interfacial area shared between the two components of the heterostructure. Besides, spheroid-like CoS 2 shows good OER and hydrazine oxidation reaction (HzOR) activity owing to the high electrochemically active surface area. In addition, the alkaline electrolyzer (HER//OER) constructed using the CoS 2 –MoS 2 (25) heterostructure and spheroid-like CoS 2 as the cathode and anode, respectively, delivers a current density of 10 mA/cm geo 2 at a cell potential of 1.67 V. Furthermore, the hydrazine-assisted electrolyzer (HER//HzOR) displays a low cell potential of 0.53 V to attain the same current density along with excellent durability up to 30 h.