Topological quantum materials for enhanced hydrogen evolution: role of bulk band structures in Pd-based alloys

Topological quantum materials (TQMs) have emerged as ideal materials for energy conversion and storage, particularly topological semimetals, featuring ultra-high electron mobility and abundant topological emergent particles (such as nodes, node lines, and node surfaces), which demonstrate great potential in the hydrogen evolution reaction (HER). Recent studies have emphasized the role of topological surface states (TSSs) in catalysis; however, the influence of bulk band structures remains underexplored. In this work, Pd alloys with transition metals (Pd₃M, M = Sn, In, and Ni) were investigated, and the results revealed that the bulk topological band crossings near the Fermi level (Pd₃Sn) optimize the adsorption of hydrogen intermediates, significantly enhancing the HER performance, as evidenced by the lower Gibbs free energy (ΔG_H) and overpotential (36 mV) and a smaller Tafel slope (23 mV dec^-1). This work provides crucial theoretical insights and design principles for developing highly active topological semimetal catalysts.