Full Composition Tuning of W1-XNbXSe2 Alloy Nanosheets to Promote the Electrocatalytic Hydrogen Evolution Reaction

Composition modulation of transition metal dichalcogenides is an effective way to engineer their crystal/electronic structures for expanded applications. Here, fully composition-tuned W1-XNbXSe2 alloy nanosheets were produced via colloidal synthesis. These nanosheets ultimately exhibited a notable transition between WSe2 and NbSe2 hexagonal phases at x = 0.6. As x approaches 0.6, point doping is converted into cluster doping and eventually separated domains of WSe2 and NbSe2. Extensive density functional theory calculations predicted the composition dependent crystal structures and phase transitions, consistently with the experiments. The electrocatalytic activity for the hydrogen evolution reaction (HER) in acidic electrolyte was significantly enhanced at x = 0.2, which was linked with the d -band center. The Gibbs free energy for the H adsorption at various basal and edge sites supported the enhanced HER performance of the metallic alloy nanosheets. We suggested that the dispersed doping structures of Nb atoms resulted in the best HER performance. Our findings highlight the significance of composition tuning in enhancing the catalytic activity of alloys.

Automated summary

Composition modulation can effectively change the crystal/electronic structures of transition metal dichalcogenides for expanded applications. In this study, fully composition-tuned W1-XNbXSe2 alloy nanosheets were successfully synthesized via colloidal synthesis, exhibiting controllable transitions between WSe2 and NbSe2 phases. The study of electrocatalytic performance showed that the hydrogen evolution reaction (HER) activity of the alloy nanosheets was significantly enhanced at x = 0.2, which was attributed to the d-band center. The dispersed doping structures of Nb atoms were suggested to contribute to the enhanced HER performance, highlighting the importance of composition tuning in catalytic activity enhancement.