MoS₂ and WS₂ Nanosheets Decorated on Metal–Organic Framework-Derived Cobalt/Carbon Nanostructures as Electrocatalysts for Hydrogen Evolution

Abstract

The replacement of platinum with nonprecious metal electrocatalysts for hydrogen evolution reaction (HER) remains an important challenge. We report facile synthesis of precious-metal-free HER electrocatalysts that are made up of metal–organic framework-derived cobalt/carbon nanostructures and semicrystalline ultrathin MoS2 or WS2 nanosheets. The as-synthesized catalysts MoS2/Co@NC and WS2/Co@NC delivered an electrochemical HER current density of 25 mA cm–2 at overpotentials of 0.23 and 0.28 V, respectively. Both the catalysts were found to be highly stable in 0.5 M H2SO4 with small Tafel slope values. The high-performance HER activity can be related to (i) covalent cobalt doping into MoS2 and WS2 layers confirmed by X-ray photoelectron spectroscopy, (ii) the presence of cobalt nanoparticles in close vicinity of MoS2 and WS2 layers, (iii) the presence of bridging disulfide S2 2– into MoS2 and WS2 layers, and (iv) synergistic cooperation among multicomponents present in the catalyst structure. Density functional theory calculations suggested that Co doping at Mo sites in MoS2 has a favorable Gibb’s free energy (ΔG) value for HER. Interestingly, the interface between the Co nanocluster and MoS2 is found to be a favorable HER active site with localization of electrons. To the best of our knowledge, the simultaneous effect of single metal substitution and metal clusters in/on MoS2 and WS2 layers has not been studied for HER. Moreover, we have also demonstrated a durable acid–base water electrolyzer using MoS2/Co@NC and WS2/Co@NC as cathodes, generating 10 mA cm–2 current density at a cell voltage of ∼0.89 V.

Advances in the Electrocatalytic Hydrogen Evolution Reaction by Metal Nanoclusters‐based Materials

“…[ 78 ] For MoS 2 layers doped with Co NCs, the DFT results showed that the CoMo interface served as preferred active centers, not only enhancing the catalytic activity of per unit active site but also improving the basal plane activity of original MoS 2 (Figure 4b, c). [ 79 ] In another work, when highly dispersed Pt NCs are loaded on the active‐site‐rich ultrathin SnS 2 , PtSn sites can significantly lower the reaction energy barrier for the HER reaction. [ 80 ] Also, by applying the first principle calculations, the atomic M 4 cluster on MN 4 ‐graphene substrate (M = Fe, Ni) is investigated, and the obtained heterometallic Ni 4 @FeN 4 ‐Gr lead to enhanced HER activity.…”

“…b) LSVs, c) The calculated Gibbs free energy. Reproduced with permission [79]. Copyright 2022, American Chemical Society.…”

Multidimensional MOF-derived carbon nanomaterials for multifunctional applications

“…As a result of their diversied and tunable nanostructures, porous MOFs have been regarded as emerging precursors for the facile syntheses of single metal sites or metal compounds (such as oxides, phosphides, suldes, selenides and others), as well as their composites for electrochemical catalysis. [178][179][180][181] On the other hand, compared with other types of MOF derivatives, multifunctional CNMs are structurally endowed with high hydrophobicity due to low polarity caused by the high graphitization degree, which greatly hinders the mass transfer and conduction process of electrocatalytic materials in a liquid. This is a common problem for MOFderived CNMs, and is also the most urgent problem to be solved at present.…”

Metal‐Organic Assembly Strategy for the Synthesis of Layered Metal Chalcogenide Anodes for Na+/K+‐Ion Batteries

“…Except for the carbon template, the MOF derivatives can also provide metal source to construct bimetallic or polymetallic dichalcogenide to regulate the active components in the composites [136–143] . In an inert atmosphere, PB‐based nanocubes can be pyrolyzed to nitrogen‐doped porous nanocubic structures with metal sites (FeCN or FeCo@C).…”