Ni3S2 nanorods growing directly on Ni foam for all-solid-state asymmetric supercapacitor and efficient overall water splitting

Transition metal compounds are attractive for their significant applications in supercapacitors and as non-noble metal catalysts for electrochemical water splitting.Herein,we develop Ni3S2nanorods growing directly on Ni foam,which act as multifunctional additive-free Ni3S2@Ni electrode for supercapacitor and overall water splitting.Based on PVA-KOH gel electrolyte,the assembled all-solid-state Ni3S2@Ni//AC asymmetric supercapacitor delivers a high areal energy density of 0.52 mWh cm-2at an areal power density of 9.02 MW cm-2,and exhibits an excellent cycling stability with a capacitance retention ratio of 89% after 10000 GCD cycles at a current density of 30 mA cm-2.For hydrogen evolution reaction and oxygen evolution reaction in 1 M KOH,Ni3S2@Ni electrode achieves a benchmark of 10 mA cm-2at overpotentials of 82 mV and 310 mV,respectively.Furthermore,the assembled Ni3S2@Ni‖Ni3S2@Ni electrolyzer for overall water splitting attains a current density of 10 mA cm-2at 1.61 V.The in-situ synthesis of Ni3S2@Ni electrode enriches the applications of additive-free transition metal compounds in high-performance energy storage devices and efficient electrocatalysis.