Bifunctional Pd sites on Pd4/Co3O4 nanowires for high selectivity of pyrazine electrocatalytic hydrogenation with water as hydrogen source

Abstract

Liquid organic hydrogen carriers (LOHCs) are considered highly promising materials for hydrogen storage. However, hydrogenation and dehydrogenation of LOHCs often require harsh reaction conditions. The hydrogenation of nitrogen-containing heterocyclic organic molecules in aqueous media is particularly challenging. This work presents an efficient electrochemical hydrogen storage system based on pyrazine as a nitrogen-containing organic hydrogen carrier. In this electrochemical system, water serves as both the solvent and the hydrogen source for pyrazine hydrogenation. Pd4/Co3O4/NF demonstrates high electrochemical activity under ambient temperature and pressure. At –0.25 V (vs. RHE), the hydrogenation conversion rate of pyrazine reaches 99.4% with the selectivity rate of 97.1%. Pd acts as the catalytic active center. It not only promotes water electrolysis to generate H*, but also facilitates the adsorption of pyrazine, providing sites for its hydrogenation. Pd4/Co3O4/NF maintains high catalytic activity after 8 cycles, showing excellent stability. This electrochemical hydrogenation of pyrazine proceeds without using hydrogen gas. Therefore, the system offers superior safety performance.