Fine regulation of Cu-ZnO interfaces for enhanced CO2 hydrogenation to methanol by atomic layer depositing thin ZnO films on copper phyllosilicates

Regulation of abundant Cu-ZnO interfaces in Cu/ZnO catalysts is critical to the thermal hydrogenation of CO 2 to methanol. Herein, Cu-ZnO interfaces were precisely regulated by depositing thin ZnO films on copper phyllosilicates (CuSiO 3 ) through atomic layer deposition (ALD) to prepare Cu/ZnO/SiO 2 composite catalysts (denoted as x ZnO/CuSiO 3 , x is the number of ALD cycles) for CO 2 hydrogenation to methanol. Interestingly, 5ZnO/CuSiO 3 exhibited much higher methanol selectivity of 68.1 % and methanol space-time yield (STY MeOH ) of 0.39 g MeOH h −1 g cat −1 toward CO 2 hydrogenation at 275 ℃ and 3 MPa, as compared to the pristine CuSiO 3 (38.1 % and 0.24 g MeOH h −1 g cat −1 ), suggesting the significant role of Cu-ZnO interfaces. Compared to ZnO/CuSiO 3 (IM) prepared by the conventional impregnation method, 5ZnO/CuSiO 3 possessed much higher CO 2 conversion (13.8 % vs. 10.1 %) and methanol selectivity (68.1 % vs. 56.2 %). Furthermore, the catalytic activities of the prepared Cu/ZnO catalysts can be effectively regulated by changing the thickness of ZnO-ALD films, in which 5ZnO/CuSiO 3 showed the best catalytic activity. Various characterization methods were applied to demonstrate that ALD-ZnO was evenly laid flat on the surface of CuSiO 3 to construct abundant Cu-ZnO interfaces during the H 2 reduction treatment, which facilitated the dissociated activation of CO 2 and formation of CH 3 O* reaction intermediate and simultaneously inhibited the generation of CO byproduct. In addition, the density functional theory (DFT) calculations revealed the stronger interaction between Cu and ZnO over 5ZnO/CuSiO 3 , which implied more Cu-ZnO interfaces were generated for methanol production. Accordingly, this study verifies the significance of Cu-ZnO interfaces for CO 2 hydrogenation to methanol and provides a facile method to regulate Cu-ZnO interfaces by depositing ALD-ZnO films on the copper phyllosilicate precursor.