Carbon coated InO hollow tubes embedded with ultra-low content ZnO quantum dots as catalysts for CO hydrogenation to methanol.

CO hydrogenation coupled with renewable energy to produce methanol is of great interest. Carbon coated InO hollow tube catalysts embedded with ultra-low content ZnO quantum dots (QDs) were synthesized for CO hydrogenation to methanol. ZnO-InO-II catalyst had the highest CO and H adsorption capacity, which demonstrated the highest methanol formation rate. When CO conversion was 8.9%, methanol selectivity still exceeded 86% at 3.0 MPa and 320 °C, and STY of methanol reached 0.98 ghg at 350 °C. The ZnO/InO QDs heterojunctions were formed at the interface between ZnO and InO(222). The ZnO/InO heterojunctions, as a key structure to promote the CO hydrogenation to methanol, not only enhanced the interaction between ZnO and InO as well as CO adsorption capacity, but also accelerated the electron transfer from In to Zn. ZnO QDs boosted the dissociation and activation of H. The carbon layer coated on InO surface played a role of hydrogen spillover medium, and the dissociated H atoms were transferred to the CO adsorption sites on the InO surface through the carbon layer, promoting the reaction of H atoms with CO more effectively. In addition, the conductivity of carbon enhanced the electron transfer from In to Zn. The combination of the ZnO/InO QDs heterojunctions and carbon layer greatly improved the methanol generation activity.