Secondary Coordination Sphere Engineering of Single‐Sn‐Atom catalyst via P Doping for Efficient CO<sub>2</sub> Electroreduction
Caizhen Yue, Xiaobo Yang, Xiong Zhang, Shifu Wang, Wei Xu, Ruru Chen, Jiuyi Wang, Jie Yin, Yanqiang Huang, Xuning Li
Abstract
Abstract The regulation of the local microenvironment in the single‐atom catalysts affords a scheme for accelerating the overall reaction kinetics of electrochemical CO 2 reduction reaction (CO 2 RR), which is of vital importance but remains challenging. Herein, a carbon nanotube‐supported single‐Sn‐atom catalyst (P‐SnN 4 ‐CNT) is developed by a modified pyrolysis procedure with P‐doping into the second coordination shell of SnN 4 moiety to modulate the electron structure of metal Sn center. The resulting P‐SnN 4 ‐CNT delivered a high CO partial current density of −380 mA cm −2 with Faradaic efficiency (FE) of CO above 90% across a wide range of −0.5 to −0.8 V versus reversible hydrogen electrode (vs RHE), along with optimal FE (CO) of ≈98.5% at −0.6 V versus RHE in a flow cell. Moreover, P‐SnN 4 ‐CNT achieved an extremely high turnover frequency of 126 471 h −1 with an applied potential of −0.8 V versus RHE, which ranks the best among the reported M─N─C catalysts for electrocatalytic CO 2 reduction. The combination of in situ characterization techniques and density functional theory calculation revealed that the doping of P atoms benefited the activation and hydrogenation steps of CO 2 and promoted the Sn 4+ reduction to Sn 2+ during the reaction process, where Sn 2+ is identified as the active site for the CO generation. The work provides a clear mechanistic insight for both electron structure optimization and identification of active sites by local microenvironment regulation of single‐Sn‐atom, which shall pave a way for the exploitation of other M─N─C catalysts with high CO 2 RR performance.