MoS2 nanoparticle morphologies in hydrodesulfurization catalysis studied by scanning tunneling microscopy

•Scanning tunneling microscopy studies of MoS2 and CoMoS nanoparticle morphologies in hydrotreating.•Morphology effect of sulfo-reductive conditions.•Morphology effect of promoter atoms (Co, Ni, Fe, Cu).•Morphology effect of supports (TiO2, graphite).

Information on the morphology and edge structures of single-layer MoS2 and promoted CoMoS nanoparticles is essential in order to understand and accurately model the activity in hydrodesulfurization catalysis. Only the edge sites in single-layer MoS2 nanoparticles are known to be active in catalysis, but since different edge structures are possible, the activity and selectivity may depend critically on the exact morphology. From atom-resolved scanning tunneling microscopy (STM) experiments, we provide here a general overview of the atomic-scale effect of sulfo-reductive atmospheres, sulfiding agents, promoter atoms, and support type on the equilibrium morphology of single-layer MoS2. Overall strong morphology variations are seen. These variations are interpreted in the framework of the Wulff construction as differences in edge energies induced by the conditions of the experiment. The results highlight the STM as an increasingly important experimental technique to investigate the atomic-scale structure of catalytically active nanoparticles in general and as one of the only tools, which can address single atom defects and single adsorption events on the atomic-scale.

Graphical abstractInformation obtained by atom-resolved scanning tunneling microscopy (STM) on the morphology and edge structures of single-layer MOSsub(2) and promoted MoS2 nanoparticles in hydrodesulfurization catalysts is reviewed with emphasis on the role of sulfiding conditions, promoters and substrate interaction.Figure optionsDownload full-size imageDownload high-quality image (107 K)Download as PowerPoint slide