Metal oxide single-component light-powered micromotors for photocatalytic degradation of nitroaromatic pollutants

Abstract

Mass transfer is a key parameter in heterogeneous reactions. Micro/nanomachines, a promising technology for environmental applications, significantly enhance the performance of conventional purification treatments because of the active motion ability and thus enhanced diffusion (superdiffusion) of these photocatalysts, which in turn leads to dramatically improved mass transfer and higher degradation capability compared to stationary microparticles. However, the design of micromotors generally involves noble metals, for instance, Au and Pt, to achieve an effective autonomous motion. Considering the expensive fabrication cost and complicated steps, we present Pt-free single-component light-powered WO3 micromotors capable of enhanced diffusion and effective degradation of nitroaromatic compounds in water. These microswimmers, synthesized by a hydrothermal method, which is highly scalable at low cost, followed by calcination, exhibit fuel-free light-driven motion due to asymmetric light irradiation. Picric acid (PA) and 4-nitrophenol (4-NP) were selected as representative nitroaromatic contaminants and photocatalytically decomposed by WO3 micromotors thanks to the close contact with the micromotors promoted by their self-propulsion. This work provides a low-cost, sustainable, scalable method for enhancing mass transfer by creating moving catalysts with broad application potential for water cleanup.

Band Engineering versus Catalysis: Enhancing the Self-Propulsion of Light-Powered MXene-Derived Metal–TiO2 Micromotors To Degrade Polymer Chains

“…Initially, a control experiment verified that MXene-derived TiO 2 microparticles show only Brownian motion under UV light irradiation in pure water, as indicated by the representative trajectories in Figure S3. This observation is in agreement with previous studies demonstrating that the self-propulsion of metal-free single-component photocatalytic semiconductor micro- and nanoparticles has been obtained for intrinsically asymmetric structures or upon exposure to directional illumination, eventually in the presence of additional H 2 O 2 fuel . The asymmetric deposition of a metal layer was expected to turn MXene-derived TiO 2 microparticles into efficient, light-powered micromotors.…”

“…This observation is in agreement with previous studies demonstrating that the self-propulsion of metal-free single-component photocatalytic semiconductor micro- and nanoparticles has been obtained for intrinsically asymmetric structures or upon exposure to directional illumination, eventually in the presence of additional H 2 O 2 fuel. 49 The asymmetric deposition of a metal layer was expected to turn MXene-derived TiO 2 microparticles into efficient, light-powered micromotors. In this regard, the first experiment aimed at evaluating micromotors’ response to repeated on–off switches of the UV light source at time intervals of approximately 10 s in pure water ( Movie S1 ).…”

Bimetallic Photo-Activated and Steerable Janus Micromotors as Active Microcleaners for Wastewater

“…7−9 On the one hand, light can not only activate their motion and act as a microstirrer for enhancing the intermixing but also work as a moving catalyst to degrade pollutants on the surface of the photocatalyst through Fenton reaction. 10,11 The magnetic field generated by an external magnetic controller can guide MNMs in their navigation in different directions, whose easy separation and recyclability are also appealing. Therefore, the "two in one" strategy is highly attractive for water remediation among researchers.…”

FeOOH Quantum Dot-Coupled Z-Scheme BiVO4/g-C3N4 Heterojunction for Enhancing Photo-Fenton Reactions

“…With the progress of science and technology, the rapid development of society also brings inevitable drawbacks. , The rapid development of industry and medicine has resulted in a higher standard of living, but at the same time, pollution has come along with it. − Large amounts of industrial wastewater and antibiotics are discharged, posing a significant environmental threat. − In recent years, removing dyes and antibiotics from wastewater has attracted more attention. − Therefore, there is an urgent need to find a photocatalyst with a broader range of adaptation and high efficiency. − …”