Electronic Properties of W’ Twin Walls in Ferroelastic BiVO₄

Topological defects in ferroic materials can exhibit intrinsic properties that differ from the bulk. Here， structural and electronic variations of non-prominent (W’) ferroelastic twin domain walls are investigated in BiVO₄, a widely investigated photocatalytic material. Using aberration-corrected scanning transmission electron microscopy (STEM), a kink configuration of the sharp ferroelastic twin wall with an altered electronic structure is revealed. Nanoscale conductivity measurements by conductive atomic force microscopy (c-AFM) show higher conductivity at twin walls compared to non-conductive bulk domains. Electronic structure investigation by electron energy loss spectroscopy (EELS) shows a higher density of oxygen vacancies and possible polaron accumulation at the wall. These findings reveal the electronic properties of BiVO₄ domain walls, which are interesting for nanoscale-engineered catalytic concepts of BiVO₄ and materials design for photochemistry-relevant applications.