Molten Salt-Mediated A-Site Cation Engineering of ABi2Nb2O9 (A = Sr, Ca, and Ba) for High-Efficiency Piezocatalytic H2O2 Production and Pollutant Degradation

Niobates have emerged as promising candidates for environmental catalysis, particularly in the realm of piezocatalysis, owing to their distinctive layered architectures and robust physicochemical performance. In this study, we report the successful fabrication of A-site cation-tailored ABi 2 Nb 2 O 9 (A = Sr, Ca, and Ba) layered oxides via a molten salt strategy. Notably, the molten salt-synthesized SrBi 2 Nb 2 O 9 exhibits superior piezocatalytic performance in H 2 O 2 evolution with a yield reaching 1836.1 µmol g −1 h −1 , approximately 2.1 times higher than that of SrBi 2 Nb 2 O 9 prepared by the solid-state method. Furthermore, this material demonstrates exceptional piezocatalytic activity, degrading 98.0% of Rhodamine B within 75 min, with a reaction rate constant of 0.04966 min −1 . In addition, the catalyst shows durable stability, maintaining 97% of its original activity after four cycles. The influence of environmental factors, including solution pH and inorganic anions (Cl − and CO 3 2− ), was also systematically evaluated. This work elucidates that the synergistic integration of A-site cation engineering and molten salt synthesis effectively modulates the piezoelectric response of ABi 2 Nb 2 O 9 (A = Sr, Ca, and Ba), offering new insights and a viable pathway for the design of novel, high-performance piezocatalysts for environmental remediation. Graphical Molten salt-mediated A-site cation engineering of ABi 2 Nb 2 O 9 effectively modulates piezoelectric response, achieving superior piezocatalytic H 2 O 2 production and pollutant degradation. This work provides a viable pathway for designing high-performance piezocatalysts for environmental remediation.