Self-adaptive evolution of nickel silicide nanowires for the enhancement of bifunctional electrocatalytic activities

Abstract

We demonstrated the electrochemical tuning (ECT) and subsequent self-adaptive evolution (SAE) of NiSi nanowires, which imparted bifunctional electrocatalytic activities comparable to those of noble-metal catalysts. Through the ECT process with lithiation and subsequent rapid delithiation in water, the NiSi nanowires developed amorphous shells dispersed with nanoparticles around intact cores, which preserved their electrical conductivity. Moreover, the amorphous shells of the NiSi nanowires exhibited structural and chemical reconstructions, which further regulated the surface states to become favorable for the O2 evolution reaction (OER) and H2 evolution reaction (HER) by enabling the lattice oxide mechanism and hydrogen adsorption energy, respectively. Because of these SAEs, the NiSi nanowires exhibited excellent electrochemical activities for both the OER and HER with overpotentials of 296 and 156 mV, respectively, at a current density of 100 mA/cm2. This study provides new opportunities for the unveiling and optimizing non-noble-metal electrocatalysts with simple compositions and earth-abundant elements.