Defected MoS₂ Modified by Vanadium-Substituted Keggin-Type Polyoxometalates as Electrocatalysts for Triiodide...

The rational design of efficient triiodide reduction reaction catalysts that are dependent on cheap and ample elements on Earth has become a challenge. As an extremely encouraging non-noble metallic catalyst, MoS₂ requires effective strategies to improve the site accessibility, inherent conductivity, and structural stability. Here, vanadium-substituted Keggin-type polyoxometalates (POMs) can be used as electron aggregates to modify manganese (Mn)-doped MoS₂ through the electrochemical deposition strategy, thereby improving the charge transfer ability of MoS₂ to I^-/I₃^- redox pairs and accelerating the reduction of I₃^-. Additionally, with the increase in the number of vanadium atoms substituted in POMs, the conduction band of POMs and MoS₂ can also match better, which effectively reduces the energy loss and is more conducive to charge transfer. Meanwhile, the deposition of POMs can improve the stability of metastable MoS₂. When POMs/MoS₂ materials are used as the counter electrodes of dye-sensitized solar cells, the power conversion efficiency (PCE) obtained is 7.27%, which is higher than that of platinum (Pt) (6.07%). The PCE can still maintain the initial 96% after 9 days. This work provides a valuable way for the improvement of platinum-free catalysts with minimal expense, basic process, high efficiency, and good stability.