Thiomolybdate Clusters: From Homogeneous Catalysis to Heterogenization and Active Sites

Abstract

Thiomolybdates are molecular molybdenum‐sulfide clusters formed from Mo centers and sulfur‐based ligands. For decades, they have attracted the interest of synthetic chemists due to their unique structures and their relevance in biological systems, e.g., as reactive sites in enzymes. More recently, thiomolybdates have been explored from the catalytic point of view and applied as homogeneous and molecular mimics of heterogeneous molybdenum sulfide catalysts. This review summarizes prominent examples of thiomolybdate‐based electro‐ and photocatalysis and provides a comprehensive analysis of their reactivities under homogeneous and heterogenized conditions. Active sites of thiomolybdates relevant for the hydrogen evolution reaction (HER) are examined, aiming to shed light on the link between cluster structure and performance. The shift from solution‐phase to surface‐supported thiomolybdates is discussed with a focus on applications in electrocatalysis and photocatalysis. The outlook highlights current trends and emerging areas of thiomolybdate research, ending with a summary of challenges and key takeaway messages based on the state‐of‐the‐art research.This article is protected by copyright. All rights reserved

Direct Anchoring of Molybdenum Sulfide Molecular Catalysts on Antimony Selenide Photocathodes for Solar Hydrogen Production

“…Based on the electrochemical and X-ray photoelectron spectroscopy (XPS) results in this study, it is hypothesized that both H 2 evolution mechanisms are in action in conjunction as there are no terminal disulfides in the [Mo 3 S 4 ] 4+ clusters; however, the higher activity of [Mo 3 S 13 ] 2− is likely due to the contributions from the disulfide based hydrogen evolution leading to a better performance. 36 Figures 4a and 4b substantiate a conformal [Mo 3 S 13 ] 2− layer with at least 6 nm thickness (which is the approximate probing depth of the Se 3d line in this measurement). This is indicated by the absence of the Sb 2 Se 3 substrate in the Sb 3d and Se 3d spectra of both the pristine and post-PEC films.…”

“…In both theories, a molecular system would mean that there are more active sites per unit area for H 2 evolution as the concentration of unsaturated Mo sites in both [Mo 3 S 4 ] 4+ and [Mo 3 S 13 ] 2– and terminal disulfides in [Mo 3 S 13 ] 2– are higher compared to MoS 2 thin films. Based on the electrochemical and X-ray photoelectron spectroscopy (XPS) results in this study, it is hypothesized that both H 2 evolution mechanisms are in action in conjunction as there are no terminal disulfides in the [Mo 3 S 4 ] 4+ clusters; however, the higher activity of [Mo 3 S 13 ] 2– is likely due to the contributions from the disulfide based hydrogen evolution leading to a better performance Figures a and b substantiate a conformal [Mo 3 S 13 ] 2– layer with at least 6 nm thickness (which is the approximate probing depth of the Se 3d line in this measurement).…”

Molybdenum Sulfide Clusters as Molecular Co-Catalyst on Antimony Selenide Photocathodes for Photoelectrochemical Hydrogen Evolution

“…Based on the electrochemical and X-ray photoelectron spectroscopy (XPS) results in this study, it is hypothesised that both H2 evolution mechanisms are in action in conjunction as there are no terminal disulphides in the [Mo3S4] 4+ clusters, however, the higher activity of [Mo3S13] 2is likely due to the contributions from the disulphide based hydrogen evolution leading to a better performance. 36…”