Topological Band Engineering of Catalysts toward Highly Efficient Electrochemical Hydrogen Evolution

Topological materials have emerged as a new frontier in physics and materials science. The non-trivial band topology gives rise to exotic physical properties such as the topologically protected surface states (TSSs). They strongly influence the surface electronic structures of the materials and could serve as a good platform to gain insight into the surface reactions. Here our interest is to design the high-efficiency hydrogen evolution reaction (HER) catalyst under the guidance of topology, reveal the role of TSSs on surface catalytic reactions, and develop a simple bulk band-based descriptor to predict the catalytic performance for various materials via ab-initio calculations in collaboration with electrochemical and photoemission experiments. To this end, we proposed a strategy for the designing of high-efficient HER catalysts by topological engineering of Pt-group-metal-based chiral crystals. We found the giant Fermi arcs can directly participate in the reactions and intrinsically boost the hydrogen desorption kinetics. As HER catalysts, PtAl and PtGa chiral crystals thus exhibit recording high intrinsic activities, even outperforming the commercial Pt catalyst. Moreover, we found that for many topological materials, in which the TSSs and trivial surface states coexist, their synergistic effect can activate the MoS2-like inert basal plane for hydrogen evolution. To have a deeper understanding of the relation between electrocatalysts and materials electronic structures, we try to extract a pure intrinsic physical parameter, the projected Berry phase (PBP), that only depends on the bulk electronic structure. Applying this parameter to the well-known non-magnetic transition metal electrocatalysts, a linear relation between the PBP and the exchange current for HER is found. This indicates that PBP can act as a descriptor for the prediction and designing of promising catalysts for HER.