Mo-doped cobalt hydroxide nanosheets coupled with cobalt phosphide nanoarrays as bifunctional catalyst for efficient and high-stability overall water splitting

Exploring earth-abundant bifunctional electrocatalysts with highly efficient activity for overall water splitting is exceedingly challenging. Herein, a facile electrodeposit-phosphating-electrodeposit strategy is developed to obtain Mo-doped Co(OH)2 nanofilms coupled with CoP nanosheets loaded on nickel foam (denoted as MoCo(OH)2/CoP/NF). Benefitting from the unique structural merits, MoCo(OH)2/CoP/NF exhibits outstanding electrocatalytic performance both for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The results indicate that the dopant of Mo in the Co(OH)2 can further improve the electrocatalytic performance. To achieve a current density of 10 mA cm−2, only 15 and 287 mV are required for HER and OER in 1 M KOH solution, respectively. When MoCo(OH)2/CoP/NF simultaneously employed as cathode and anode for overall water splitting, it only requires 1.593 and 1.853 V to achieve 10 and 50 mA cm−2, respectively. The electrocatalytic activity of MoCo(OH)2/CoP/NF for overall water splitting even exceed the benchmark electrode couple of Pt/C/NF||RuO2/NF, and MoCo(OH)2/CoP/NF perform excellent durability for overall water splitting. This work opens up new avenues for large-scale commercial production of overall water splitting catalysts due to its low-cost and facile method.