Boosting the Performance\nof Electrochemical CO<sub>2</sub> Reduction to HCOOH through the Interaction\nof Pyridinic Nitrogen\nwith Sn

The development of efficient and stable catalysts for\nelectrochemical\nCO<sub>2</sub> reduction (CO<sub>2</sub>RR) to formic acid (HCOOH)\nis of great practical significance for balancing energy and environmental\nissues. SnO<sub>2</sub> shows potential application of the CO<sub>2</sub>RR to HCOOH, while its low current carrier density and inappropriate\nadsorption energy for crucial intermediates limit its performance\nin terms of activity and selectivity. In this study, phthalocyanine\n(Pc) and tetraphenyl porphyrin (TPP) were loaded onto SnO<sub>2</sub> nanosheets forming composite materials with different types of N\n(SnO<sub>2</sub>/Pc and SnO<sub>2</sub>/TPP), respectively. In Pc,\nboth pyridinic N and pyrrolic N are present, while only pyrrolic N\nis present for TPP. XPS analysis reveals that the obvious electronic\ninteraction happened between the pyridinic N and Sn, regulating the\nelectronic states of Sn sites. As a result, SnO<sub>2</sub>/Pc composites\ncan selectively convert CO<sub>2</sub> to HCOOH with a Faraday efficiency\nup to 90.25% and partial current density up to 16.15 mA cm<sup>–2</sup> at −1.3 V vs RHE, higher than SnO<sub>2</sub>/TPP and SnO<sub>2</sub>. Density functional theory (DFT) calculations further prove\nthat the superior catalytic performance of SnO<sub>2</sub>/Pc comes\nfrom its moderate adsorption energy for *OCHO and *HCOOH, which is\nbeneficial for *HCOOH desorption.