Mechanical-energy-driven HCHO purification with lattice distortion engineering and surface grafting

Fe-doped Bi4Ti3O12 nanosheets with PEI grafting for efficient adsorption-enhanced piezocatalytic oxidation of HCHO is realized, showing a good potential for the air purification. [Display omitted] •The lattice distortion improved the piezoelectricity of Bi4Ti3O12.•The doping of Fe ions narrowed the bandgap and enhanced electrons transfer by valence transition.•The surface grafting of PEI greatly enhanced the adsorption ability to HCHO.•PEI with abundant electron-donating amino groups can quickly trap holes during carrier separation.•The possible piezocatalytic mechanism was proposed. Formaldehyde (HCHO) is a typical indoor air pollutant with high toxicity and wide distribution. It is of great significance to use clean energy for efficient catalytic oxidation of HCHO. In this work, Fe-doped bismuth titanate (Bi4Ti3O12) nanosheets with polyethyleneimine (PEI) grafting were prepared, exhibiting a remarkable complete elimination of HCHO under ultrasonic vibration. Piezocatalytic mechanism analysis revealed that Fe3+ doping induced lattice distortion and accelerated the transfer of electrons through valence change. Additionally, the abundant amino groups in PEI efficiently gathered formaldehyde molecules on the surface of the catalysts for next catalytic reaction as well as accelerate the separation of carriers by trapping holes as strong electron donors. It showed an effective strategy for degrading organic pollutants in the air with adsorption-enhanced piezocatalysts driven by mechanical energy.