Revealing the Origin of Graphene Anchored Single Palladium Atom for Electrochemical CO2 Reduction to Syngas with Tunable CO/H2 Ratios

Abstract

AbstractPd based catalysts are rare metal‐based catalyst to yield tunable CO/H2 ratios for Fischer‐Tropsch synthesis. How to achieve the co‐production of CO and H2 with as little Pd as possible is extremely meaningful for Cn industry. Recent experiment revealed single Pd atom anchored on graphene exhibits high activity for CO2 electroreduction to syngas, yet the origin of activity and controllable CO/H2 ratios, especially the exact Pd coordination structure, remains elusive. Here we employ grand‐canonical density functional theory to show that Pd−N1, rather than the commonly accepted Pd‐N4, serves as the active center, and the charge‐carrying capability is an effective descriptor. The site with more Pd−C coordination can better submerge in graphene‘s delocalized π electrons for higher charge‐carrying capacity to carry excess charges that occupy Pd 4dz2 orbital and promote electron injection. Importantly, the tunable CO/H2 ratio can be explained with difference in charge‐carrying capability of transition state for *COOH and *H2 formation. This work solves the puzzle of coordinating structure of Pd active site and demonstrates the important role of charge‐carrying capability in electrochemical process, which shall provide a reference for further exploration of efficient electrocatalysts.