In-situ hydrothermal synthesis of MnO2/NiO@Ni hetero structure electrode for hydrogen evolution reaction and high energy asymmetric supercapacitor applications

In-situ deposition of MnO2/NiO hetero structure on Ni-foam has been carried out through simple one-step hydrothermal reaction. The in-situ deposited multi-metal oxide shows extraordinary electrocatalytic activity in hydrogen evolution reaction with a small Tafel slope of 38 mV per decade and very low onset potential of 0.17 V. An electrolyser has been fabricated with MnO2/NiO deposited Ni-foam which effectively achieves a current density of similar to 24 mA cm(-2) at an applied voltage of similar to 1.57 V. Furthermore, the metal oxide deposited on Ni-foam is directly used as the supercapacitor electrode which shows good rate capability as positive electrode materials. An asymmetric capacitor (ASC) has been assembled by using the MnO2/NiO deposited Ni-foam as positive electrode and thermally reduced graphene oxide as negative electrode. The assembled ASC has a large specific capacitance of 218 F g(-1) at a current density of 3 A g(-1) and can deliver high energy and power density of 59.5 Wh kg(-1) and 25,350 W kg(-1), respectively. The ASC shows very good electrochemical stability throughout 10,000 charge-discharge cycles along with the capability to work in the high frequency range. (C) 2016 Elsevier Ltd. All rights reserved.