Heterostructured Palladium–Nickel Sulfide on Plasma-Activated Nickel Foil for Robust Hydrogen Evolution

Abstract

Transition-metal sulfides are among the effective electrocatalyst candidates for H2 evolution (HER); however, they still cannot compete with Pt-based electrodes for renewable energy applications. To overcome this issue, grid-matched palladium–nickel sulfides (Pd4S/Ni3S2) are successfully engineered on the holey surface of nickel foil (HNF), which is first treated with a non-thermal plasma (HPNF) generated by a dielectric barrier discharge. The synthesized heterogeneous Pd4S-Ni3S2/HPNF catalyst results in the electron redistribution on the phase interfaces, enhancing the desorption ability of H* species. Consequently, Pd4S-Ni3S2/HPNF presents a high HER activity, and the overpotentials for generating 10 (j10) and 500 (j500) mA/cm2 are about 44 and 247 mV. Meanwhile, the catalyst retains good electrocatalytic stability over 50 h at j100. In addition, the H2 amount of Pd4S-Ni3S2/HPNF driven by the current j10 can reach 11.25 mmol/h, which is competitive with other presently available high-performance electrocatalysts. The theory and in situ Raman spectroscopy results indicate that Pd4S and the heterointerfaces between the Pd4S and Ni3S2 phases are the main active catalytic sites for H2 evolution and that the Pd weakens the S–Hads bonds, enhancing the reactive kinetics of the Volmer and Heyrovsky steps. This work provides a new and green approach for engineering highly active and stable electrocatalysts for clean hydrogen production.