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

• Binder free MnO2/NiO@Nielectrode was developed.
• MnO2/NiO@Ni shows superior HER activity with low onset potential of 0.17 V.
• MnO2/NiO@Ni was used as the positive electrode of supercapacitor.
• ASC device shows high energy density of 59.5 Wh kg−1.
• ASC remains 75% stable after 10,000 CD cycles.

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 ∼24 mA cm−2 at an applied voltage of ∼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.

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