Coupling of a thermal and electrochemical activated Ni nanothorn array electrode for highly robust hydrogen generation

Abstract

Industrially profitable alkaline electrolyzers are among the vital challenges in developing a feasible and renewable hydrogen economy. The widely available electrocatalysts are effective for hydrogen generation at low current density (∼10 mA cm⁻²); howbeit, enormous efforts are required to meet industrial expectations to acquire large current density (>500 mA cm⁻²) for practical water splitting applications. Herein, we demonstrate that thermal effects can regulate the electron transfer at the interface between the alkaline electrolyte and nickel nanothorn array (Ni NTA) surface, leading to extraordinary hydrogen evolution reaction (HER) at large current density. The Ni NTA electrode tested at a relatively high temperature of 60 °C manifests the ability to generate a large current density of 1000 mA cm⁻² at an overpotential of merely 140 mV, comparable to that of platinum-based electrodes and dramatically lower than that of recently reported Ni-based catalysts. The simulation result reveals that the production of H⁺ ions increases around the tip of the nanothorn structure as the temperature increases from room temperature, which greatly promotes the faster reaction kinetics and mass transfer. This work can provide opportunities for implementing earth-abundant catalysts with exceptional performance for industrial electrolyzers at large current densities.