Polyethylenimine promoted electrocatalytic reduction of CO2 to CO in aqueous medium by graphene-supported amorphous molybdenum sulphide

Abstract

Efficiently and selectively converting CO₂ to value-added carbon compounds remains a major challenge in sustainable energy research. In this paper, we report the synthesis of a cost-effective catalyst, i.e. amorphous molybdenum sulphide on a polyethylenimine modified reduced graphene oxide substrate, for electrocatalytically reducing CO₂ into CO in CO₂ saturated aqueous NaHCO₃ medium with high efficiency and selectivity. The catalyst is capable of producing CO at overpotentials as low as 140 mV and reaches a maximum faradaic efficiency of 85.1% at an overpotential of 540 mV. At an overpotential of 290 mV with respect to the formation of CO, it catalyzes the formation of syngas with high stability. Detailed investigations reveal that PEI works as a co-catalyst by providing a synergetic effect with MoS_x.