Single B-doped palladium electrocatalyst Enabling direct cathodic coupling of carbon dioxide with methanol into dimethyl carbonate

Abstract

Dimethyl carbonate (DMC) is a green chemical of large market demand with widespread applications. Direct cathodic coupling of carbon dioxide (CO2) with methanol (CH3OH) into DMC represents a green and sustainable electrochemical route yet remains a great challenge. Reported electrochemical syntheses of DMC from CO2 and CH3OH necessitate the use of toxic methyl iodine or carcinogenic propene oxide. Herein, we for the first time employ a nanosized B-doped palladium catalyst (Pd-B) to realize the direct electrosynthesis of DMC through cathodic coupling of CO2 and CH3OH, which no longer requires any hazardous reagent. Under the optimal condition, the DMC Faradaic efficiency reaches to 47.5 % at 30 mA/cm2, and the yield of DMC is up to 257.3 umol.h−1. A thorough mechanistic investigation has proven that the DMC electrochemical synthesis in our work involves three cascade reactions including CO2-to-CO reduction, methanol-to-methoxide (CH3O–) activation and coupling of CO with CH3O–, simultaneously occurring on the surface of Pd-B catalyst assisted by bromine (Br2) generated at the anode. Two key intermediates in the decisive coupling step, CH3OCO* and CH3O*, are detected on the surface of Pd-B catalyst by In situ ATR-SEIRAS. This work provides a first example of direct cathodic coupling of CO2 and CH3OH into DMC, and the mechanistic investigations in this work will benefit the future design of advanced Pd-based catalysts toward DMC electrosynthesis.