Oxygen vacancy-induced dipole moment enhancement in BiVO₄ for efficient pyro-catalytic hydrogen evolution

Pyroelectric catalysis utilizes temperature fluctuations to drive hydrogen production reactions, but its application is limited due to the relatively weak spontaneous polarization intensity of most materials. Electron localization function (ELF) and density functional theory (DFT) calculations demonstrate that the presence of oxygen vacancies induces an asymmetric charge distribution in the BiVO₄ lattice and disrupts its local symmetry. This distortion leads to an enhanced local dipole moment, thereby effectively improving the macroscopic spontaneous polarization capability. The COMSOL simulation indicates that the fluctuation of temperature difference and the pyroelectric potential exhibit a nonlinear response relationship. The polarization field induced by the pyroelectric effect effectively promotes the separation of electrons and holes, resulting in a remarkably high hydrogen evolution rate of 5.38 mmol h^-1 g^-1 for BiVO₄-V_O. This work not only provides profound atomic-level insight into the defect-mediated polarization enhancement mechanism but also establishes a practical foundation for designing high-performance pyroelectric catalysts that can efficiently harvest low-grade waste heat for sustainable hydrogen production.