Activating self-supported NiPd electrodes by laser-direct-writing for efficient hydrogen evolution reaction†

Abstract

Pd-based catalytic electrodes for the hydrogen evolution reaction (HER) are promising as a replacement of Pt-based catalysts, but their strong hydrogen adsorption hinders hydrogen desorption and thus limits HER catalytic activity. Here, we report a function–structure integrated D-Ni_3.5Pd/NF catalytic electrode with a very low Pd loading (0.19 mg_Pd cm⁻²) and a large number of edge dislocations, which was prepared by millisecond laser direct writing in liquid nitrogen. The plentiful dislocations induce a strain effect leading to reduced hydrogen adsorption energies of Pd sites and enhanced water dissociation ability of Ni sites. Thereby, the dense dislocations improve the alkaline HER intrinsic activity and electrochemical stability of D-Ni_3.5Pd/NF under high current densities. The as-prepared electrodes can achieve fairly low overpotentials of 35 and 352 mV at 10 mA cm⁻² and 1 A cm⁻² in a 1 M KOH electrolyte, respectively, while the Tafel slope is only 62.3 mV dec⁻¹. In addition, its overpotential only increases by 4.2% after 100 h of the chronoamperometric test at 500 mA cm⁻², showing an outstanding electrochemical stability at high current densities.