Achieving Simultaneous CO2 and H2S Conversion via a Coupled Solar-Driven Electrochemical Approach on Non-Precious-Metal Catalysts

Carbon dioxide (CO2) and hydrogen sulfide (H2S) are generally concomitant with methane (CH4) in natural gas and traditionally deemed useless or even harmful. Developing strategies that can simultaneously convert both CO2 and H2S into value-added products is attractive; however it has not received enough attention. A solar-driven electrochemical process is demonstrated using graphene-encapsulated zinc oxide catalyst for CO2 reduction and graphene catalyst for H2S oxidation mediated by EDTA-Fe2+/EDTA-Fe3+ redox couples. The as-prepared solar-driven electrochemical system can realize the simultaneous conversion of CO2 and H2S into carbon monoxide and elemental sulfur at near neutral conditions with high stability and selectivity. This conceptually provides an alternative avenue for the purification of natural gas with added economic and environmental benefits.