Self-supported hollow Co(OH)2/NiCo sulfide hybrid nanotube arrays as efficient electrocatalysts for overall water splitting

Developing low-cost and earth-abundant electrocatalysts with high activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is highly desired but still remains a significant challenge. Herein, hollow cobalt hydroxide/NiCo sulfide hybrid (Co(OH)2/Ni-Co-S) nanotube arrays are synthesized on nickel foam (NF) through a simple hydrothermal method and subsequent sulfurization, which serve as efficient electrocatalysts for overall water splitting. The optimized Co(OH)2/Ni-Co-S-8h electrocatalyst requires overpotentials of 300 mV and 340 mV to reach current densities of 30 and 100 mA cm−2 for the OER in 1.0 M KOH, respectively. In addition, the optimized Co(OH)2/Ni-Co-S-8h electrocatalyst requires overpotentials of 148 mV and 254 mV to reach the current densities of 10 and 100 mA cm−2 for the HER in the same electrolyte, respectively. Furthermore, the electrolyzer used as efficient catalysts for overall water splitting requires cell voltage of 1.62 V to obtain 10 mA cm−2.