Hierarchical CoNi2S4@NiMn-layered double hydroxide heterostructure nanoarrays on superhydrophilic carbon cloth for enhanced overall water splitting

In the current work, hierarchical CoNi2S4@NiMn-layered double hydroxide heterostructure nanoarrays on superhydrophilic carbon cloth (CoNi2S4@NiMn LDH/SCC) is proposed as an efficient bifunctional electrocatalyst for enhanced overall water splitting. Prepared with a simple hydrothermal method, the electrocatalyst is simultaneously active towards oxygen evolution reaction (OER) (overpotentials of 269, 301, and 312 mV at 100, 300, and 500 mA cm−2 respectively) and hydrogen evolution reaction (HER) (overpotentials of 82, 184, and 224 mV at 10, 100, and 200 mA cm−2 respectively). Besides, when it was used as both cathode and anode for overall water splitting, the cell voltages at 10, 50, 100, and 200 mA cm−2 are as low as 1.502, 1.642, 1.691, and 1.748 V, respectively. Furthermore, its cell voltage can remain constant at 50 mA cm−2 for 12 h. The hierarchical heterostructure nanoarrays have some advantages acting as a bifunctional water-splitting electrocatalyst: (1) the high electrical conductivity of core material and high intrinsic activity of shell material can function simultaneously to compensate each other’s drawbacks in the heterostructure; (2) since the sulfur within the core material will be selectively removed under OER potential window if directly contacting with the electrolyte, the shell material ensures the durability of this catalytic system by acting as a protective layer; (3) the superhydrophilic features of carbon cloth support is beneficial to the uniform growth of catalysts and accelerating mass transport.