Piezotronic-Enhanced Photoelectrochemical Reactions in Ni(OH)₂‑Decorated ZnO Photoanodes

Controlling the interface electronic band structure in heterostructures is essential for developing highly efficient photoelectrochemical (PEC) photoanodes. Here, we presented an enhanced oxygen evolution reaction (OER) by introducing the piezotronics concept, i.e., piezoelectric polarization (P_pz)-induced band engineering. In a Ni­(OH)₂-decorated ZnO photoanode system, appreciably improved photocurrent density of sulfite (SO₃^2–) and hydroxyl (OH^–) oxidation reactions were obtained by physically deflecting the photoanode. Both theoretical and experimental results suggested that the performance enhancement was a result of the piezoelectric P_pz-endowed enlargement of the built-in electric field at the ZnO/Ni­(OH)₂ interface, which could drive an additional amount of photoexcited charges from ZnO toward the interface for OER. This strategy demonstrates a new route for improving the performance of inexpensive catalysts-based solar-to-fuel production.