Ni(OH)2/CoS heterostructure grown on carbon cloth for robust supercapacitor and methanol electrocatalytic oxidation
Guosheng Wang, Zhihua Xu, Zhikun Li, Yingjie Ding, Ruixiang Ge, Ming Xiang, Geming Wang, Zhaoxiong Yan
Abstract
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 Co 2+ /Co 3+ redox cycle for the rapid conversion of Ni 2+ into Ni 3+ , 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).