Ni(OH)2/CoS heterostructure grown on carbon cloth for robust supercapacitor and methanol electrocatalytic oxidation

Heterojunction construction is a promising strategy to enhance the charge transfer efficiency, which subsequently optimizes the utilization of the electrode material. Herein, the constructed Ni(OH)2 nanosheets on ZIF-67-derived CoS core deposited on carbon cloth (Ni(OH)2/CoS/CC) possesses a superior performance (561.6 mA h g–1 at 1 A g–1) to Ni(OH)2/CC electrode (199.4 mA h g–1). Hybrid supercapacitor (HSC) with a Ni(OH)2/CoS/CC cathode and an active carbon (AC) anode (Ni(OH)2/CoS/CC//AC) provides a remarkable energy density of 90.8 W h kg–1 at 800 W kg–1 and keeps 59.7 W h kg–1 even at 25,600 W kg–1, higher than most of the reported Ni(OH)2-related device, and possesses a marvelous capacity retention of 92.2% over 10,000 charge-discharge cycles. Concurrently, Ni(OH)2/CoS/CC as an efficient electrocatalyst displays an excellent electro-catalytic activity towards methanol oxidation. The outstanding electrochemical performance of Ni(OH)2/CoS/CC is chiefly due to the mediation of the Co2+/Co3+ redox cycle for the rapid conversion of Ni2+ into Ni3+, which greatly boosts the charge-transfer efficiency in the supercapacitors and methanol electro-oxidation. This work provides a rational way to obtain high-power electrode material for supercapacitors (SCs) and electrocatalytic methanol oxidation in direct methanol fuel cells (DMFCs).