Design of bimetallic nickel-iron quantum dots with tunable compositions for enhanced electrochemical water splitting

Electrochemical water splitting is a viable approach to address the increasing demands for sustainable alternative energy resources and an envisioned hydrogen economy. Nickel and iron have emerged as promising electrocatalysts for the hydrogen production. Here we report on the synthesis of bimetallic quantum dot (QD) based electrocatalysts comprised of nickel and iron with a tunable composition via an environment-friendly method and their effects on the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The Ni:Fe ratio was optimized and tuned for enhanced electrochemical catalytic activity of the formed QDs. The optimal compositions of NiFe QD based electrocatalysts were found to be 54.9% Ni and 25.3% Ni towards the OER and HER, respectively. The first principles density functional theory (DFT) calculations were conducted to elucidate the synergistic effect of the NiFe QDs, revealing that the electronic properties such as the band gap energy and density of states (DOS) could be optimized by tuning the composition of the formed NiFe QDs. The approach described in the present study could be easily adapted to synthesize various QDs as advanced electrocatalysts for the efficient hydrogen production to address the pressing energy and environmental challenges.