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

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 [email protected]@Ni3S2 with a 3D porous structure. Due to the intrinsic catalytic activity and continuous NiNi network of Ni3S2, 3D porous structure of NF and the excellent electron conductivity of the graphene as well as their synergistic effects, [email protected]@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 [email protected]@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, [email protected][email protected]3S2 also showed an excellent stability for all HER, OER and overall water-splitting, demonstrating a potential prospect of [email protected]@Ni3S2 for the practical application. Our work opens up a new direction for the development of non-noble metal electrocatalysts.