Self-Interconnected Porous Networks of NiCo Disulfide as Efficient Bifunctional Electrocatalysts for Overall Water Splitting.

Electrochemical splitting of water has been viewed as a highly efficient technique to produce clean hydrogen and oxygen energy. However, designing inexpensive multifunctional electrocatalysts with high performance is a great challenge. Here, a unique three-dimensional catalyst of self-interconnected porous Ni-Co disulfide networks grown on carbon cloth [(Ni0.33Co0.67)S2 nanowires (NWs)/CC] was prepared by a facile hydrothermal method coupled with further low-temperature sulfuration strategy. As a bifunctional electrocatalyst, (Ni0.33Co0.67)S2 NWs/CC exhibits a remarkable activity to catalyze both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). To drive a current density of 100 mA cm-2, (Ni0.33Co0.67)S2 NWs/CC needs the overpotentials of 156 mV in 0.5 M H2SO4 solution and 334 mV in 1.0 M KOH solution for HER, respectively. Moreover, when used as a catalyst of OER, (Ni0.33Co0.67)S2 NWs/CC needs an overpotential of 295 mV to produce a current density of 100 mA cm-2. The excellent electrochemical properties are mainly attributed to the synergetic catalysis of a Ni-Co-based bimetallic disulfide, the porous network structure, and the high conduction of CC. Moreover, the two-electrode alkaline water-splitting system constructed by (Ni0.33Co0.67)S2 NWs/CC only needs a low cell voltage of 1.57 V to approach 10 mA cm-2. This work offers more new insights for the design and preparation of the non-noble metal catalysts based on transition metal sulfides with excellent electrocatalytic performance in overall water splitting.