Immobilization of well-dispersed Ag nanoparticles on calcium niobate nanosheets as highly active catalyst towards reduction of 4-nitrophenol

Ag nanoparticles were successfully deposited onto calcium niobate nanosheets using the electrostatic self-assembly method, followed by UV irradiation photoreduction. Various characterization techniques including XRD, SEM, HRTEM, BET and XPS have been utilized to study the material crystalline structure, microstructure, pore size and surface properties. Silver nanoparticles in the size range of 2-8 nm are well dispersed on the surface of the calcium niobate nanosheets. The as-synthesized Ag-Ca2Nb3O10 was a mesoporous material with a broad pore size distribution. Ag-Ca2Nb3O10 exhibited remarkable catalytic activity for the reduction of 4-nitrophenol (4-NP) by NaBH4 solution under ambient conditions, and no obvious activity degradation was observed after 5 cycles of durability test. The reduction has a pseudo-first-order rate constant of 18.01 x 10(-3) s(-1) and an activity parameter of 6.00 s(-1) g(-1). The activation energy (E-a) of the reduction reaction was calculated as 59.63 kJ mol(-1). The catalyst was recycled several times without any significant catalytic activity loss. This work provides a facile route to synthesize a highly efficient catalyst for the reduction of organic pollutants. (C) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.