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A piezocatalyst with highly efficient catalytic efficiency toward multiple pollutants' removal can improve treatment efficiency and reduce the consumption of catalysts, which is ideal for practical applications. Herein, Bi5Ti3FeO15 nanofibers were prepared using electrospinning and its excellent piezocatalytic performances for mixed dyes' and antibiotics' degradation were revealed. Rhodamine B (RhB) is degraded by 98% in 20 min, and the acquired reaction rate constant is 0.195 min–1 under ultrasonic vibration. Particularly, the mixed dyes of RhB, acid orange 7, methylene blue, and methyl orange are simultaneously degraded within 40 min, a high rate constant of 0.106 min–1 is achieved, and the degradation efficiencies can be always maintained at ∼100% for five consecutive cycles. The obtained rate constant for mixed dyes' degradation is superior to many of the previously reported catalysts just toward one dye degradation. Furthermore, it is further demonstrated that tetracycline hydrochloride, bisphenol A, and phenol can be also efficiently degraded by 94, 90, and 79%, respectively, within 30 min. The piezocatalytic performances of nanofibers at different pH values and reaction temperatures were also explored. Catalytic mechanism investigations demonstrate that the optimized Bi5Ti3FeO15 nanofibers possess a weaker carrier recombination rate, smaller carrier transfer resistance, and higher carrier separation efficiency, which account for its superior piezocatalytic performance. This work reveals that Bi5Ti3FeO15 nanofiber is a superior catalyst for organic pollutants' degradation under mechanical vibration and offers a strategy for the design of other high-performance piezocatalysts. [ABSTRACT FROM AUTHOR]

Mechanical energy can be directly transformed into chemical energy by piezoelectric materials, namely, piezocatalysis, which is a potential tactic for renewable clean energy collection and environmental purification. The piezocatalytic efficiency strongly relies on the piezoelectric property and free charge concentration of piezocatalysts. Here, four samarium-doped (1 – x)-Pb-(Mg1/3Nb2/3)-O3-xPbTiO3 nanostructures were designed to investigate the correlation between the piezoelectric property and piezocatalytic performance. The diverse dye degradation efficiencies confirmed the high piezoelectric coefficient toward high catalytic activity. The degradation efficiency for acid orange 7 (AO7) was 100% within 20 min, while those for methyl orange (MO), methylene blue, and rhodamine B dyes were 97, 78, and 72%, respectively, within 40 min under ultrasonic vibration only. Furthermore, high catalytic efficiency of 96% was still maintained for AO7 degradation after 10 consecutive degradation cycles for samarium-doped 0.70Pb-(Mg1/3Nb2/3)-O3-0.30PbTiO3 due to its high piezoelectric coefficient. The investigation of the catalytic mechanism demonstrated that hole and superoxide radicals were the primary active species toward AO7 degradation, whereas hydroxyl and hole radicals were for MO degradation. This work not only demonstrates the highly efficient catalytic activity of samarium-doped (1 – x)-Pb-(Mg1/3Nb2/3)-O3-xPbTiO3 nanostructures but also gives a deep comprehension of the correlation between the piezoelectric property and catalytic performance of piezocatalysts. [ABSTRACT FROM AUTHOR]

A rapid increase in methicillin-resistant Staphylococcus aureus (MRSA) induced infection has been noticed in recent years and the biofilm formed by MRSA further delays wound healing, causing a high mortality rate. Hence, a safe and effective superoxide radical (O 2 •- ) mediated self-synthesis strategy is developed to prepare Au-doped MoO 3- x (Au/MoO 3- x ) plasmonic-semiconductor hybrid for the elimination of MRSA mediated wound infection. The synthesis mechanism of Au NPs is systematically investigated, proving that O 2 •- plays a key role in reduction of HAuCl 4 into Au NPs in the presence of H 2 O and O 2 . Au-doped MoO 3- x exhibits the improved photothermal conversion efficiency (∼52.40%) compared with MoO 3- x (∼41.11%). Moreover, the peroxidase (POD)-like activity of Au/MoO 3- x hybrid is higher than that of MoO 3- x NPs, resulting in increased yield of highly toxic ·OH. In combination with the enhanced photothermal and POD-like properties, Au/MoO 3- x hybrid achieves efficient elimination of MRSA bacteria with eradication ratio of ∼99.76%. Additionally, the as-prepared Au/MoO 3- x NPs exhibit excellent biosafety, which is verified via in vitro and in vivo experiments. This study provides the basis for exploring MoO 3- x -based hybrids via a green O 2 •- -mediated self-synthesis approach.

The unique piezoelectric potential of piezoelectrics could lead to performance gains for electrochemical catalysis. Here, a cuboid-like Na 0.5 Bi 0.5 TiO 3 (NBTO) piezoelectric micron crystal was synthesized by a hydrothermal process. The piezocatalytic and visible light assisted piezo-photocatalytic activities of NBTO were investigated. Surprisingly, under ultrasonic vibration and visible light irradiation, the NBTO exhibited four times faster degradation rate than that under ultrasonic vibration only, although the NBTO doesn't absorb visible light. An efficient coupling between piezoelectric effect and visible light photoexcitation in NBTO was directly demonstrated. The improved piezo-photocatalytic performance is attributed to the piezoelectric potential and the decrease of bandgap of NBTO micron crystal due to strain induced by ultrasonic vibration. A new fundamental mechanism for the improved degradation of organic dye has been proposed for piezoelectric and photoexcitation coupling. This work extends the application of wide band gap piezoelectric materials in the visible light area., Competing Interests: There are no conflicts of interest., (This journal is © The Royal Society of Chemistry.)