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.