Stabilizing Hydrous β-NiOOH for Efficient Electrocatalytic Water Oxidation by Integrating Y and Co into Amorphous Ni-Based Nanoparticles

Abstract

A two-stage ball milling process was used to synthesize amorphous Ni79.2Nb12.5Y8.3 and Ni74.2Co5Nb12.5Y8.3 nanoparticles from elemental powders. The two-stage ball milling process provides a scalable and industrially applicable method for producing non-metalloid amorphous nanoparticles. The amorphous nanoparticles displayed excellent catalytic performance toward the oxygen evolution reaction (OER) in 1 M KOH, displaying lower overpotentials than IrO2 at 10 mA cm-2. The addition of Co in the amorphous alloy reduced the overpotential to 288 mV at 10 mA cm-2. The pairing of X-ray photoelectron spectroscopy and in situ X-ray absorption spectroscopy revealed that the improved OER activity of amorphous Ni74.2Co5Nb12.5Y8.3 was attributed to the catalytic synergy between Y and Co. The integration of Y supported proton-coupled electron-transfer processes that assisted with the electrostatic adsorption of OH- and formation of oxyhydroxide species, while Co sites enabled metal-oxo bonding to prevent Ni overcharging and the stabilization of β-NiOOH. The catalytic synergy between Y and Co reduces the amount of Co needed to enhance the OER activity of Ni-based alloys and lessens the dependence on Co, which is in high demand in many renewable energy and storage applications.