Enhanced ammonia production via synergistic piezo-photocatalysis using TiO2@layered silicate magadiite nanosheets

Abstract

This study presents a piezocatalyst, TiO₂@layered silicate magadiite nanosheets (TiO₂@LSM), which leverages the photocatalytic properties of anatase TiO₂ nanoparticles (NPs) to enhance nitrogen reduction performance. By purging N₂ gas into pure water and applying simultaneous ultrasonic vibration and light exposure, the TiO₂@LSM nanosheets achieved an impressive ammonia production rate of 5.41 mg L⁻¹ g_cat⁻¹ h⁻¹, representing a 4.40-fold and 2.15-fold increase over purely photocatalytic and piezocatalytic processes, respectively. Time-resolved photoluminescence (TRPL) and photoluminescence (PL) analyses confirmed that the piezo-induced internal electric field effectively extends the lifetime of charge carriers in the TiO₂@LSM nanosheets. Finite element method (FEM) simulations further demonstrated that the deposition of TiO₂ NPs on LSM broadens the potential distribution and significantly enhances the piezoelectric potential, consistent with experimental findings. The study evaluated ammonia production efficiency under various conditions—piezocatalysis, photocatalysis, and combined piezo-photocatalysis—achieving NH₃ yields of 1.23, 2.51, and 5.41 mg L⁻¹ g_cat⁻¹ h⁻¹, respectively. This work introduces a straightforward method for developing catalysts that efficiently utilize both mechanical and light energy for ammonia synthesis from nitrogen, offering a sustainable approach with no wastewater or byproducts, and highlighting its potential for green energy applications.