Strained few-layer MoS2 with atomic copper and selectively exposed in-plane sulfur vacancies for CO2 hydrogenation to methanol
Shenghui Zhou, Wenrui Ma, Uzma Anjum, Mohammadreza Kosari, Shibo Xi, Sergey M. Kozlov, Hua Chun Zeng
Abstract
Abstract In-plane sulfur vacancies (Sv) in molybdenum disulfide (MoS 2 ) were newly unveiled for CO 2 hydrogenation to methanol, whereas edge Sv were found to facilitate methane formation. Thus, selective exposure and activation of basal plane is crucial for methanol synthesis. Here, we report a mesoporous silica-encapsulated MoS 2 catalysts with fullerene-like structure and atomic copper (Cu / MoS 2 @SiO 2 ). The main approach is based on a physically constrained topologic conversion of molybdenum dioxide (MoO 2 ) to MoS 2 within silica. The spherical curvature enables the generation of strain and Sv in inert basal plane. More importantly, fullerene-like structure of few-layer MoS 2 can selectively expose in-plane Sv and reduce the exposure of edge Sv. After promotion by atomic copper, the resultant Cu / MoS 2 @SiO 2 exhibits stable specific methanol yield of 6.11 mol MeOH mol Mo –1 h –1 with methanol selectivity of 72.5% at 260 °C, much superior to its counterparts lacking the fullerene-like structure and copper decoration. The reaction mechanism and promoting role of copper are investigated by in-situ DRIFTS and in-situ XAS. Theoretical calculations demonstrate that the compressive strain facilitates Sv formation and CO 2 hydrogenation, while tensile strain accelerates the regeneration of active sites, rationalizing the critical role of strain.