In Operando Identification of In Situ Formed Metalloid Zinc δ+ Active Sites for Highly Efficient Electrocatalyzed Carbon Dioxide Reduction.

Electrochemical CO 2 -to-CO conversion provides a possible way to address problems associated with the greenhouse effect; however, developing low-cost electrocatalysts to mediate high-efficiency CO 2 reduction remains a challenge on account of the limited understanding of the nature of the real active sites. Herein, we reveal the Zn δ+ metalloid sites as the real active sites of stable nonstoichiometric ZnO x structure derived from Zn 2 P 2 O 7 through operando X-ray absorption fine structure analysis in conjunction with evolutionary-algorithm-based global optimization. Furthermore, theoretical and experimental results demonstrated that Zn δ+ metalloid active sites could facilitate the activation of CO 2 and the hydrogenation of *CO 2 , thus accelerating the CO 2 -to-CO conversion. Our work establishes a critical fundamental understanding of the origin of the real active center in the zinc-based electrocatalysts for CO 2 reduction reaction.