Efficient electrochemical hydrogenation and dehydrogenation of quinoxaline over a dendritic structure P-WO3/NF electrode

Abstract

Liquid organic hydrogen carrier (LOHC) has been recognized as a highly promising candidate for hydrogen storage materials in addressing hydrogen utilization issues. However, the hydrogenation and dehydrogenation of LOHC typically require noble metal catalysts and harsh reaction conditions. In this paper, we proposed an efficient reversible electrochemical hydrogen storage system based on a nitrogen heterocyclic organic hydrogen carrier, quinoxaline, in which water was used as the solvent and hydrogen source for quinoxaline hydrogenation, and a self-supporting dendritic P-WO3/NF electrode was employed as the electrocatalyst. The catalytic properties of P-WO3/NF for electrochemical hydrogenation of quinoxaline and dehydrogenation of 1,2,3,4-tetrahydroquinoxaline were studied in 1 M KOH solution under mild conditions. The results showed that the hydrogenation conversion of quinoxaline was 90%, the selectivity was 99%, and the dehydrogenation conversion of 1,2,3,4-tetrahydroquinoxaline was 100%, the selectivity was 100%. This indicates that the system has high conversion efficiency, outstanding selectivity, and good reversibility. Meanwhile, the P-WO3/NF electrode adapted to the system exhibited good catalytic stability. In addition, no pre-prepared external hydrogen was required in the electrochemical hydrogenation reaction involving water, which gave the system an excellent safety profile. The reversible electrochemical hydrogen storage system established by this work broadens the vision of LOHC in hydrogen storage applications.