Balanced Adsorption Toward Highly Selective Electrochemical Reduction of CO2 to Formate

Tin-based materials have been designed as potential catalysts for the electrochemical conversion of CO2 into a single product. However, such tin-based materials still face the challenges of unsatisfactory selectivity, because the rate-determining step is situated within the slow desorption step. In this work, a variety of tin-based materials are synthesized using the electrospinning technique in an effort to control the adsorption strength during electrochemical reduction, therefore improving the selectivity of CO2 reduction toward formate. The optimized SnS material exhibits moderate adsorption strength to *OCHO and *HCOOH, and the appropriate atomic distance of Sn-Sn maintained the balanced adsorption posture of both intermediate. Therefore, the rate-determining step can be shifted from the slow desorption of the *HCOOH step (Sn) to the first hydrogenation of the *OCHO species step (SnS). Due to this shift, the SnS/C electrode demonstrated excellent selectivity, with a Faradaic efficiency of 96% for the production of formate. A maximum current density of -12.5 mA cm-2 for formate is also achieved for a period of 33 h.Tin-based materials have been designed as potential catalysts for the electrochemical conversion of CO2 into a single product. However, such tin-based materials still face the challenges of unsatisfactory selectivity, because the rate-determining step is situated within the slow desorption step. In this work, a variety of tin-based materials are synthesized using the electrospinning technique in an effort to control the adsorption strength during electrochemical reduction, therefore improving the selectivity of CO2 reduction toward formate. The optimized SnS material exhibits moderate adsorption strength to *OCHO and *HCOOH, and the appropriate atomic distance of Sn-Sn maintained the balanced adsorption posture of both intermediate. Therefore, the rate-determining step can be shifted from the slow desorption of the *HCOOH step (Sn) to the first hydrogenation of the *OCHO species step (SnS). Due to this shift, the SnS/C electrode demonstrated excellent selectivity, with a Faradaic efficiency of 96% for the production of formate. A maximum current density of -12.5 mA cm-2 for formate is also achieved for a period of 33 h.