Synergistic Enhancement of Methanol Formation by Edge-Site FeOx Clusters and In-Plane Vacancies on MoS2 for CO2 Hydrogenation.

MoS2 is a promising catalyst for methanol synthesis from CO2 hydrogenation. It is widely accepted that the in-plane sulfur vacancies are the active sites for methanol formation, while the edge sulfur vacancies catalyze methane formation, which is typically undesirable. Rather than blocking the edge sites with heteroatom dopants, we demonstrate that decorating the edges of MoS2 with functional FeOx clusters effectively boost methanol formation via synergy between the RWGS activity of the anchored FeOx clusters and the CO hydrogenation activity of the in-plane sulfur vacancies. Synthetically, this was achieved by a vacuum impregnation method that chemically anchors FeOx clusters on the edges of MoS2, forming stable Fe-S/Fe-O interfaces. With these Fe-S/Fe-O interfaces, the Fe/MoS2 catalyst shows markedly enhanced methanol selectivity (to 80%) and a high intrinsic space-time-yield (STY) of 0.6 mmolCH3OH·m-2·h-1. In situ spectroscopic and microscopic characterizations combined with theoretical calculations corroborate that the formation of amorphous FeOx clusters at edge sites of MoS2 could effectively suppress edge Sv formation, generate additional CO*, and promote the formation of methanol at the in-plane Sv sites. Broadly speaking, this work has demonstrated the modulation of MoS2 edge sites using simple and scalable catalyst preparation methods to enhance methanol formation.