Electrochemical syngas production from CO2 and water with CNT supported ZnO catalysts

Nanocrystalline ZnO/CNT with enhanced electrochemical reduction of CO2 to syngas [Display omitted] •Faradaic efficiency of synthesis gas of more than 75% was achieved on small ZnO particles.•The H2/CO ratio can be tailored by the ZnO particle size.•DFT study revealed the ZnO surface stabilizes CO2* and COOH* intermediates, therefore more active for CO2 activation.•ZnO is promising for electrochemical syngas production. Electrochemical reduction of CO2 and H2O can provide a promising pathway to synthesis gas generation for renewable electric energy storage and fuel production with the closed anthropogenic carbon cycle. However, the lack of affordable highly active catalysts to activate the stable CO2 and H2O molecules presents a substantial challenge. Here we report ZnO supported on nanocarbon as a cost-effective and active catalyst for selective conversion of CO2 and H2O to predominately synthesis gas, with higher selectivity and activity compared to polycrystalline metal catalysts such as Ag and Cu. The H2/CO ratio can be tailored for different industrial processes by tuning the applied potential and the particle size of ZnO. Density functional theory calculations showed that the higher activity of ZnO is related to more significantly stabilized intermediates, CO2*, COOH, and CO* compared to Cu and Ag. Our results highlight a promising class of low-cost, abundant oxide as active electrocatalysts for synthetic fuel production from CO2.