Oxygen vacancy engineering in MOF-derived AuCu/ZnO bimetallic catalysts for methanol synthesis via CO2 hydrogenation

Abstract

Three AuCu/ZnO bimetallic catalysts, AuCu/ZnO-BTC, AuCu/ZnO-BDC and AuCu/ZnO-MOF-74, were derived from various MOF precursors using facile hydrothermal methods. Among the resultant catalysts, the AuCu/ZnO-BTC catalyst possessed the best methanol synthesis activity, whose space time yield of methanol (STYMeOH) reached 359.0 gMeOH kgcat−1 h−1 at 250 °C under 3 MPa. Structural characterization reveals that in comparison with the AuCu/ZnO-BDC and AuCu/ZnO-MOF-74 catalysts, the AuCu/ZnO-BTC catalyst possessed higher specific surface area (SBET), tinier metal particle size, more oxygen vacancies, stronger metal-support interactions and larger amount of medium basic sites. In situ DRIFTS result demonstrates that formate (*HCOO) species were readily generated and bridged-methoxy (*b-OCH3) species were selectively formed on the AuCu/ZnO-BTC catalyst, which may be related with its abundant oxygen vacancies and responsible for its superior methanol synthesis activity. The present work derives high-performance AuCu/ZnO bimetallic catalysts from MOF precursors and provides new insight into structure-activity relationships for CO2 hydrogenation to methanol.