Silverton-type polyoxometalate-derived electrocatalyst for efficient hydrogen evolution in acidic and alkaline media
Abstract
High efficiency and durable non-noble-metal electrocatalysts for the hydrogen evolution reaction (HER) are essential for large-scale green hydrogen production. In this work, a trimetallic polyoxometalate (POM) precursor H2[Co(NH3)6]2[CeMo12O42] (Co2CeMo12) was synthesized via the self-assembly of POM. Subsequently, Co and Ce co-doped MoS2 electrocatalyst (Co,Ce-MoS2@CC) was in situ grown on carbon cloth (CC) through a one-step hydrothermal sulfidation process. This precursor strategy effectively avoids phase separation and interfacial mismatch, which are the two major drawbacks of conventional doping routes. Experimental results combined with density functional theory (DFT) calculations demonstrate that Ce3+/Ce4+ redox pairs modulate the interfacial charge distribution of the catalyst. The doped Co species serve as electron acceptors to balance the electron enrichment induced by Ce, thereby optimizing the HER kinetics and the adsorption/desorption free energy of reaction intermediates. In 1.0 M KOH, the optimized Co,Ce-MoS2@CC requires an overpotential of only 58 mV to achieve 10 mA cm-2, while in 0.5 M H2SO4, 118 mV is needed. It maintains stable electrocatalysis over 72 h at a high current density of 100 mA cm-2 in both alkaline and acidic electrolytes. This work proposes a POM precursor-mediated Co-Ce co-doping strategy that exhibits potential for scalable fabrication of high-performance MoS2-based non-noble-metal electrocatalysts, suitable for HER applications.