Doping Design on Reconstructed NbAs(001) Surfaces for Enhanced Hydrogen Evolution: Theoretical Calculations and Experimental Validation

Abstract

Weyl semimetals hold promise for use in various electrochemical and photocatalytic processes, but their application is often hindered by poor performance. For instance, niobium arsenide (NbAs), a archetypal Weyl semimetal, exhibits poor hydrogen evolution reaction (HER) performance in both acidic and alkaline environments. Using ab initio molecular dynamics (AIMD) simulations, we show that the NbAs(001) surface reconstructs during HER due to the formation of an As-As σ bond through Py orbital overlap. High-throughput screening of various doping elements in both the bulk and on the surface identified tantalum (Ta) as the most promising candidate. Our calculations of the hydrogen adsorption energy and water dissociation energy demonstrate that Ta doping significantly enhances HER performance. To confirm our computational predictions, we synthesized pure-phase NbAs and Ta-doped NbAs (Ta-NbAs) using chemical vapor transport (CVT). Through X-ray photoelectron spectroscopy (XPS) and electrochemical characterization, we reveal, for the first time, the surface reconstruction mechanism of a Weyl semimetal during HER. At an highest doping concentration of 3.63%, the material shows a remarkable enhancement in HER performance under both acidic and alkaline conditions. Specifically, in acidic media, the overpotential at a current density of 10 mA/cm² was reduced by 26.3%, and the charge transfer kinetics improved by 73%. Under alkaline conditions, the electrochemical active surface area increased by 60.14%. These findings validate a computational-guided strategy for doping element screening as an effective method for optimizing material properties and provide a new paradigm for the rational design of high-performance catalysts.