The role of formate species for CO₂ hydrogenation is still under debate. Although formate has been frequently observed and commonly proposed as the possible intermediate, there is no definite evidence for the reaction of formate species for methanol production. Here, formate formation and conversion over the ZnZrO_x solid solution catalyst are investigated by in situ/operando diffuse reflectance infrared Fourier transform spectroscopy-mass spectroscopy (DRIFTS-MS) coupled with density functional theory (DFT) calculations. Spectroscopic results show that bidentate carbonate formed from CO₂ adsorption is hydrogenated to formate on Zn–O–Zr sites (asymmetric sites), where the Zn site is responsible for H₂ activation and the Zr site is beneficial for the stabilization of reaction intermediates. The asymmetric Zn–O–Zr sites with adjacent and inequivalent features on the ZnZrO_x catalyst promote not only formate formation but also its transformation. Both theoretical and experimental results demonstrate that the origin of the excellent performance of the ZnZrO_x catalyst for methanol formation is associated with the H₂ heterolytic cleavage promoted by the asymmetric Zn and Zr sites.

中文翻译：

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ZnZrOx 催化剂上的不对称位点促进 CO2 加氢中甲酸盐的形成和转化

_{CO 2}氢化的甲酸盐种类的作用仍在争论中。尽管甲酸盐经常被观察到并且通常被认为是可能的中间体，但没有明确的证据表明甲酸盐物种会反应生成甲醇。在这里，通过原位/原位漫反射红外傅立叶变换光谱-质谱 (DRIFTS-MS) 结合密度泛函理论 (DFT) 计算研究了ZnZrO _{x固溶体催化剂上的甲酸盐形成和转化。}光谱结果表明，由 CO ₂吸附形成的双齿碳酸盐在 Zn-O-Zr 位点（不对称位点）上氢化为甲酸盐，其中 Zn 位点负责 H ₂活化和 Zr 位点有利于反应中间体的稳定。_{ZnZrO x}催化剂上具有相邻和不等价特征的不对称 Zn-O-Zr 位点不仅促进了甲酸盐的形成，还促进了甲酸盐的转化。_{理论和实验结果均表明，ZnZrO x}催化剂对甲醇形成的优异性能的起源与不对称Zn和Zr位点促进的H ₂异裂解有关。