Boron nanoclusters endowed NiFe layered double hydroxides with efficient bifunction toward ammonia oxidation reaction and hydrogen evolution reaction

Coupling ammonia oxidation reaction (AOR) and hydrogen evolution reaction (HER) provides a hybrid water splitting system to reduce the energy consumption of hydrogen production significantly, solve the safety problem of H2/O2 mixing in the overall water splitting, and remove ammonia nitrogen from wastewater. Herein, amorphous boron nanoclusters are deposited onto NiFe layered double hydroxide nanosheets (B-NiFe-LDH/NF) via in-situ electroreduction, proposed to form a bifunctional catalyst toward the AOR and HER. Since the electron-deficient boron induces surface electronic recombination of LDH and facilitates the exposure of substantial high-valent Ni and Fe metal active sites, this B-NiFe-LDH/NF exhibited high activity with a voltage of 1.781 V at a current density of 100 mA cm-2, 202 mV lower than that required in overall splitting water, accompanying with 78.6% of the ammonia removal rate after 24 h of electrolysis. In addition, density functional theory (DFT) simulation indicated that the induction of boron nanoclusters decreased the energy barrier, facilitating the adsorption–desorption of ammonia and the Volmer step.