3D porous and self-supporting Ni foam@graphene@Ni3S2 as a bifunctional electrocatalyst for overall water splitting in alkaline solution

摘要

Low-cost transition metal sulfides are considered as one kind of the most promising catalysts for the electrochemical water-splitting. In this work, a facile electrochemical method was employed to directly deposit Ni3S2 on Ni foam (NF) decorated with graphene (G) for the construction of a self-supporting electrocatalyst NF@G@Ni3S2 with a 3D porous structure. Due to the intrinsic catalytic activity and continuous Ni-Ni network of Ni3S2, 3D porous structure of NF and the excellent electron conductivity of the graphene as well as their synergistic effects, NF@G-5@Ni3S2 exhibited an excellent electrocatalytic performance. In the alkaline solution, the low overpotentials of 119 and 249 mV were required to reach a current density of 10 mA cm(-2) for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. And the Tafel slopes were only 64.8 and 98.2 mV dec(-1) for HER and OER, respectively. Remarkably, by employing NF@G-5@Ni3S2 as both anode and cathode for full water splitting, a very low cell voltage of 1.62 V was needed to reach 10 mA cm(-2). Moreover, NF@G-5@Ni3S2 also showed an excellent stability for all HER, OER and overall water-splitting, demonstrating a potential prospect of NF@G-5@Ni3S2 for the practical application. Our work opens up a new direction for the development of non-noble metal electrocatalysts. (C) 2019 Elsevier B.V. All rights reserved.