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

Abstract

Layered double hydroxide (LDH) catalysts provide promising oxygen evolution reaction (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 inferior hydrogen evolution reaction (HER) activity. Here, 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 hours.

Ni and Co Active Site Transition and Competition in Fluorine‐Doped NiCo(OH)2 LDH Electrocatalysts for Oxygen Evolution Reaction

“…According to the above discussion, the doped F‐atoms induce the lattice strain, modulate the electronic interaction, and even influence the d‐band center, thereby improving the catalytic OER activity. [ 46 ]…”

Graphene Architecture-Supported Porous Cobalt–Iron Fluoride Nanosheets for Promoting the Oxygen Evolution Reaction

“…In practical water splitting, it is impossible to directly produce hydrogen because the efficiency of the reaction is very low. Functionalized catalysts not only reduce the activation energy of the electrolyzed water reaction but also decrease the overpotential during the oxygen evolution reaction (OER) [ 5 , 6 ]. Therefore, the quality of the catalyst determines the total voltage for the practical electrolysis of water and the conversion efficiency of electrical energy into hydrogen energy.…”