Anisotropic Strain Boosted Hydrogen Evolution Reaction Activity of F-NiCoMo LDH for Overall Water Splitting

Abstract

Layered double hydroxide (LDH) catalysts provide promising OER activity which can be employed in overall water splitting for hydrogen production. However, their weak surface hydrogen adsorption (Had) and high water dissociation energy can result in the inferior hydrogen evolution reactions (HER) activity. In this paper, a highly efficient HER catalyst of F-doped NiCoMo LDH is successfully designed and synthesized through in situ growing on nickel foam (F-NiCoMo LDH/NF) for overall water splitting. DFT calculations demonstrate that the introduction of Mo and F atoms in NiCo LDH can induce the generation of anisotropic lattice strain, resulting in the generation of high-energy active interface and shifting the d-band centers. Therefore, the adsorption energy of Had is optimized and the water dissociation energy barrier is decreased. As a result, this F-NiCoMo LDH/NF catalyst electrode displays a low overpotential of 107.5 mV at 10 mA cm−2 and a small Tafel slope of 67.2 mV dec−1 for HER. The assembled electrolyzer by employing this catalyst electrode requires only 1.83 V to deliver 300 mA cm−2 and operates stably for 100 h.