Band tilt with enhanced charge separation induced by Nb-doped piezoelectric to boost photocatalysis

Abstract

Activating the inherent piezoelectric effect of materials as an auxiliary driving force for photocatalytic performance is considered a reliable approach for developing a new generation of efficient photocatalytic systems, but research on modification strategies for optimizing piezoelectric performance is still in its infancy. In this work, we developed Nb-doped NaNbO₃ (N-NNO-4) piezoelectric based on self-doping strategy. Under the combined action of ultrasonic vibration and solar light irradiation, N-NNO-4 can generate high concentrations of hydroxyl radicals (•OH) in water environment, thereby achieving excellent oxidation performance. N-NNO-4 exhibits excellent piezo-photocatalytic performance in water pollution control applications. The reaction kinetic coefficients of its use as a piezo-photocatalyst for purifying common plasticizers dimethyl phthalate are 8.5 times and 6.8 times those of its use as a photocatalyst and piezocatalyst, respectively, and 17 times that of undoped NaNbO₃ (NNO) piezo-photocatalyst. Mechanism analysis shows that the excellent piezo-photocatalytic performance is not only attributable to the efficient charge separation efficiency induced by Nb-doped and the improved charge transfer ability, but also originate from the synergistic effect of band tilt caused by piezoelectric effect and efficient activation of interface H₂O caused by Nb-doped. The synergistic effect opens up new channels for •OH generation and significantly intensifies the formation of •OH. The present study explores the feasibility of constructing an efficient piezoelectric photocatalytic system based on self-doping strategy, providing theoretical reference and experimental basis for utilizing green energy in nature to achieve sustainable environmental protection and development.