Polyoxometalates as a precursor in one-pot synthesis of MoS2-V2O5@CC for electrocatalytic hydrogen evolution

A research group led by Professor Pingfan Wu at Hubei University of Technology has recently developed a novel strategy for the fabrication of V₂O₅/MoS₂ composite electrocatalytic, which entails the one-pot hydrothermal synthesis using polyoxometalates (POMs) as a precursor. This approach ingeniously leverages the differential preferential affinities of molybdenum (Mo) and vanadium (V) toward sulfur and oxygen, respectively. The as-prepared MoS₂-V₂O₅@CC catalyst demonstrates excellent hydrogen evolution reaction (HER) performance (achieving 100 mA·cm^-2 with an overpotential of only 244 mV) and remarkable long-term stability (retaining 80% activity after 100 hours) under alkaline conditions. This work thus provides a new and feasible synthetic pathway for the rational design of high-performance composite electrocatalysts for HER.

Professor Wu's research group firstly synthesized the Lindqvist-type POM (C₁₆H₃₆N)₂ Mo₃V₃O₁₆(OCH₂)₃CCH₂CH₃ (Mo₃V₃). Single-crystal X-ray diffraction revealed its core structure to be a Tris-Et anchored heterometallic oxygen cluster with a Mo/V ratio of 1:1.

Using Mo₃V₃ as a precursor, a MoS₂-V₂O₅ heterojunction composite material was constructed in-situ on carbon cloth via a one-step hydrothermal method (MoS₂-V₂O₅@CC). This strategy cleverly utilizes the intrinsic differences in the affinity of Mo and V for sulfur and oxygen: in a sulfurizing environment, Mo is fully sulfurized to form MoS₂ nanoflowers; V, due to its oxophilic nature, forms a V₂O₅ thin film coating the carbon fibers, creating a core-shell heterojunction with MoS₂. Furthermore, benefiting from the homogeneity of the POM precursor, the metal elements are uniformly mixed and exhibit strong interfacial coupling within the composite material, effectively preventing phase separation and agglomeration.

The catalyst samples were systematically characterized by various methods. XRD and XPS analysis confirmed the close integration of MoS₂ and V₂O₅, revealing strong electronic interactions between them that induce lattice expansion in V₂O₅. SEM and TEM showed that the V₂O₅ thin film uniformly coats the carbon fiber substrate, tightly coupling with the three-dimensionally grown MoS₂ nanoflowers to form a stable core-shell heterostructure. This structure allows the V₂O₅ thin film to function as "conductive glue," enhancing interfacial bonding while providing abundant active sites. The lattice overlap at the interface between the two phases further confirms their strong interaction.

The electrode exhibits lower charge transfer impedance and a greater abundance of active sites, with a mass activity more than four times that of MoS₂@CC. In a 1 M KOH electrolyte, the catalyst requires an overpotential of only 244 mV to achieve a current density of 100 mA·cm^-2, significantly outperforming MoS₂@CC and V₂O₅@CC. More importantly, the stable core-shell structure of the catalyst effectively addresses the key challenge of V₂O₅ materials being prone to dissolution and deactivation in aqueous electrolytes, endowing the electrode with excellent long-term stability.

This research offers a new synthetic approach for designing efficient and stable non-noble metal electrocatalysts and highlights the potential application of POM in the field of energy materials.

About the Authors

Pingfan Wu, distinguished Professor of the inaugural "Nanhu Scholars Program". Director of the Institute of POM Materials, and Leader of the university-level Premium Course "Organic Chemistry" at Hubei University of Technology, has presided over and completed multiple national, provincial, and ministerial-level research projects, and published more than 50 SCI-indexed papers in international top-tier journals such as Angew. Chem. Int. Ed., Chem. Eng. J., and J. Mater. Chem. A. As a pioneer in guiding undergraduates without prior research experience into the field of scientific research, she took the lead in proposing the concept that "undergraduate research training should start upon enrollment", and with university-level innovation and entrepreneurship projects as the incubation carrier, she has successfully practiced the "undergraduate-master-doctoral integrated" talent training model, which has gained widespread recognition in academic circles.

About Journal

Polyoxometalates (ISSN 2957-9821) is a peer-reviewed (single-blind), open-access and interdisciplinary journal, sponsored by Tsinghua University. Polyoxometalates publishes original high-quality research papers and significant review articles that focus on cutting-edge advancements in Polyoxometalates, and clusters of metals, metal oxides and chalcogenides. Rapid review to ensure quick publication is a key feature of Polyoxometalates. It is indexed by ESCI, Scopus (CiteScore 2024 = 14.7), Ei Compendex, CAS, and DOAJ. For details about Polyoxometalates, please visit: https://www.sciopen.com/journal/2957-9821.