Mesoporous-assembled TiO2-NiO-Ag nanocomposites with p-n/Schottky heterojunctions for enhanced photocatalytic performance

Construction of Schottky heterojunctions with plasmonic metals and p-n heterojunctions with p-type semiconductors have been considered as two effective approaches for boosting photocatalytic activity of TiO2. Here, we report on a magnetically-recyclable TiO2-NiO-Ag p-n/Schottky heterojunction photocatalyst fabricated by a facile and two-step approach combining spark discharge generation of mixed metallic nanoparticles under a protective argon atmosphere and a suitable thermal annealing process at air. Our comprehensive characterization studies revealed the formation of a mesoporous nano-heterostructure consisting of defective TiO2 nanoparticles that were finely incorporated with well-dispersed p-type NiO and Ag nanoparticles. Thanks to its extremely high surface area (223.07 m(2) g(-1)), reduced optical band gap (similar to 1.88 eV), improved visible-light absorption (similar to 26% within 400-900 nm), and suppressed charge carriers recombination rate, our structure exhibited an enhanced photocatalytic degradation efficiency of 93.8% and a mineralization efficiency of 87.5% within 90 min irradiation towards methylene blue decomposition, superior to those of pure TiO2, NiO, and TiO2-NiO samples. This nanocomposite structure shows a large potential for practical application in the areas of environmental remediation and other photocatalytic applications. (C) 2021 Elsevier B.V. All rights reserved.