Microscopic understanding of electrocatalytic reduction of CO2 on Pd-polyaniline composite: an ab initio study.

The reaction mechanism for the electroreduction of CO2 on polyaniline (PANI) and its composite with a single palladium atom (Pd/PANI) has been investigated employing ab initio density functional theory. It is observed that the Pd/PANI composite can capture and activate CO2 more efficiently than those for the cases of individual systems (PANI and Pd atom). Moreover, it is found that both PANI and Pd/PANI show high selectivity for the formation of formic acid (HCOOH) over the methanol (CH3OH) production. The electroreduction of CO2 towards formic acid (HCOOH) follows two different pathways, depending on the catalyst: on PANI the formation of HCOOH occurs through the *COOH intermediate, whereas for the case of Pd/PANI, the same reaction proceeds through the formation of formate (*OCHO). While the formation of CH3OH from CO2 on PANI is not feasible, electroreduction of CO2 towards CH3OH on Pd/PANI occurs through the formation of CO.