Palladium(II)–N‑Heterocyclic Carbene Complex-Based Electrocatalysts for Hydrogen Evolution Reaction

The growing interest in the hydrogen economy demands for the sustainable and efficient production pathways from renewable sources. Among the arrays available, electrochemical hydrogen evolution reaction (HER) is considered as an efficient and sustainable approach for proton reduction to produce green hydrogen gas from water. The current work employs the construction of electrocatalysts developed from carbon composites of palladium(II) complexes derived from functionalized N-heterocyclic carbenes (NHCs). The developed electrocatalysts are studied for their HER performance in an acidic medium using a rotating ring disk electrode setup, displaying an overpotential as low as −449 mV versus reversible hydrogen electrode (RHE) with an onset potential of −240 mV versus RHE. The palladium complex-based carbon composites demonstrated improved charge transfer resistance (55–68 Ω) than that of palladium–NHC complexes (65–80 Ω). The confirmation of HER was investigated by hydrogen oxidation reaction enabled by the ring electrode. The developed electrocatalysts exhibit excellent stability for up to 10 h with minimal decrease in efficiency, as indicated by the post-stability linear sweep voltammogram. The post-HER analysis of the electrocatalysts indicates the structural and molecular intactness.