Comprehensive First-Principles Study on the Multifaceted Properties of Four BiVO4 Polymorphs: Unraveling the Structure-Property Relationships.

Bismuth vanadate (BiVO4) has emerged as a widely studied photocatalytic material for water splitting and pollutant degradation owing to its favorable band gap of approximately 2.4 eV, favorable chemical stability, and environmental compatibility. Using first-principles calculations, we systematically investigated the multiscale properties of four BiVO4 polymorphs (sm, op, zt, and st-BiVO4). Results demonstrate that sm-BiVO4 exhibits the narrowest band gap (2.23 eV) among the four polymorphs and the highest adsorption stability, with only one unstable configuration identified among 21 adsorbate-facet combinations. This superior stability is attributed to structural distortion that induces local polarization and lone-pair electrons, which effectively facilitate the separation of photogenerated charge carriers. This polymorph also exhibits higher visible light absorption coefficients than those of st-BiVO4 across the energy range of 2.06-3.50 eV and shows stable surface adsorption. Thermodynamically, zt-BiVO4 is more stable, whereas mechanical analysis reveals that sm-BiVO4 possesses high hardness and modulus but lower ductility. This study systematically elucidates the structure-property relationships of BiVO4 from electronic, optical, adsorptive, thermodynamic, and mechanical perspectives, thereby establishing a theoretical foundation for the rational optimization of its photocatalytic performance.