Synthesis of strontium chromate-nitrogen and sulfur co-doped graphene and its potential for electrochemical hydrogen storage

Abstract

In the present study, monazite-type strontium chromate (SrCrO4) as a ternary metal oxide was prepared by the sol-gel method. Nitrogen and sulfur co-doped graphene decorated with SrCrO4 nanocrystals was synthesized successfully, and the electrochemical hydrogen storage performance of the SrCrO4 and its relative nanocomposites also were investigated by chronopotentiometry (CHP) technique. The effect of doped graphene as a substrate of the SrCrO4 sample on the improvement of the electrochemical hydrogen storage performance was considered as well. The SrCrO4-nitrogen and sulfur co-doped graphene (SrCrO4/NSG) displayed the highest discharge capacity in comparison to SrCrO4-reduced graphene oxide (SrCrO4/rGO), SrCrO4 calcined at 1000 °C (SrCrO4 (1000)) and SrCrO4 calcined at 800 °C (SrCrO4 (800)). Also, increasing the hydrogen storage capacity of the samples by repeating the cycles indicated the excellent cycle stability of the nanoparticles. In monazite-type structures, oxygen vacancies can be created by thermal treatment. Creating oxygen vacancies can improve redox reactions, which increase the conductivity of the samples and hydrogen storage capacity.