Ultra-high piezo-photocatalytic performance of (Na, Sm) co-doped CaBi2Nb2O9 nanoplates by the surface effect†

Piezo-photocatalysis is an emerging means to efficiently relieve energy crises and environmental problems. In this work, (Na, Sm) co-doped CaBi₂Nb₂O₉ nanoplates with an average thickness of ∼100 nm are prepared by a molten salt method. The ultra-high piezo-photocatalytic performance is achieved by modulating the calcination temperature with a first-order kinetic constant (k) of impressive 0.7734 min⁻¹ for 10 mg L⁻¹ RhB, superior to most similar reported studies. The catalytic universality for other colored pollutants (methylene blue, methyl orange, and indigo carmine), antibiotics (tetracycline, tetracycline hydrochloride, and oxytetracycline), and an optimum hydrogen production of 183.60 μmol g⁻¹ h⁻¹ is demonstrated. The outstanding catalytic performance derives from the unique (Bi₂O₂)²⁺ layers, the dominant surface effect, and piezoelectric assistance. The synergistic effect of piezocatalysis and photocatalysis is described using the energy band bending mechanism and the separation behaviors of carriers. This work provides a feasible strategy for the preparation of powerful piezo-photocatalysts.