Oxidative stress induced by reactive oxygen species (ROS) is one of the most important antibacterial mechanisms of engineered nanoparticles (NPs). To elucidate the ROS generation mechanisms, we investigated the ROS production kinetics of seven selected metal-oxide NPs and their bulk counterparts under UV irradiation (365 nm). The results show that different metal oxides had distinct photogenerated ROS kinetics. Particularly, TiO(2) nanoparticles and ZnO nanoparticles generated three types of ROS (superoxide radical, hydroxyl radical, and singlet oxygen), whereas other metal oxides generated only one or two types or did not generate any type of ROS. Moreover, NPs yielded more ROS than their bulk counterparts likely due to larger surface areas of NPs providing more absorption sites for UV irradiation. The ROS generation mechanism was elucidated by comparing the electronic structures (i.e., band edge energy levels) of the metal oxides with the redox potentials of various ROS generation, which correctly interpreted the ROS generation of most metal oxides. To develop a quantitative relationship between oxidative stress and antibacterial activity of NPs, we examined the viability of E. coli cells in aqueous suspensions of NPs under UV irradiation, and a linear correlation was found between the average concentration of total ROS and the bacterial survival rates (R(2) = 0.84). Although some NPs (i.e., ZnO and CuO nanoparticles) released toxic ions that partially contributed to their antibacterial activity, this correlation quantitatively linked ROS production capability of NPs to their antibacterial activity as well as shed light on the applications of metal-oxide NPs as potential antibacterial agents.

Textile materials have been enriched in function at the composite level with continuous developments in the textile industry. Zinc oxide (ZnO) nanoparticles (ZnO-NPs) are strongly influenced by ultraviolet (UV) filter, antifungal, high catalysis, and semiconductor/piezoelectric coupling characteristics. Therefore, the antibacterial property and UV resistance of ZnO-NP materials are zcomprehensively analysed to provide a basis for applying ZnO-NP in the textile industry. In addition, the textile preparation and application of ZnO-NP in piezoelectric power generation is discussed. Based on relevant documents for ZnO-textile industry applications, scanning electron microscopy analysis, biological activity analysis, and UV transmittance analysis of textiles containing composite materials prove that textiles based on ZnO-based composite materials (ZnO-NP materials) have antibacterial properties and UV resistance. The antibacterial property and UV resistance of ZnO-NP materials are analysed comprehensively to provide a basis for applying ZnO-NP in the textile industry. After the photocatalytic reaction, its practical application as slurry type suspensions is limited because of the difficulty of separating the catalyst particles. In terms of its piezoelectric power generation characteristics, intensity of current voltage analysis and X-ray diffraction analysis reveal that textiles based on ZnO-NP materials have obvious semiconductor characteristic and obvious current enhancement signals locally, indicating that the textiles can achieve better piezoelectric properties.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

In the photocatalytic conversion of CO2 to valuable chemicals under aqueous conditions, the selectivity and the product yield still present the most challenging issues. Against this backdrop, negatively charged water-soluble CdS nanocrystals were used to assemble with a positively charged dinuclear cobalt complex through electrostatic interactions. This assembly efficiently catalyzes the CO2-to-CO conversion under visible light, with a high selectivity of 95%, a high yield of 34.51 μmol of CO, and a large turnover number (TON) of 1380 based on the cobalt catalyst, all of which are record high values for a noble-metal-free visible-light-driven CO2 reduction system with a molecular catalyst in a fully aqueous medium.

Lead halide perovskite (LHP) nanocrystals have recently been actively investigated for photocatalysis, owing to their inexpensive fabrication and excellent optoelectronic properties. However, LHP nanocrystals have not been used for artificial photosynthesis in aqueous solution, owing to their high sensitivity to water. In this study, water‐tolerant cobalt‐doped CsPbBr3/Cs4PbBr6 nanocrystals have been prepared with the protection of hexafluorobutyl methacrylate. The resultant materials are employed as efficient photocatalysts for visible‐light‐driven CO2 reduction in pure water. The perovskite nanocrystals with 2 % cobalt doping afford an impressive overall yield of 247 μmol g−1 for photocatalytic CO2 conversion into CO and CH4, using water as an electron source. This study represents a significant step for practical artificial photosynthesis by using LHP nanocrystals as photocatalysts in aqueous solution.

The instability and low inferior catalytic activity of metal-halide perovskite nanocrystals are crucial issues for promoting their practical application in the photocatalytic field. Herein, we in situ coat a thin graphdiyne (GDY) layer on CsPbBr3 nanocrystals based on a facile microwave synthesis method, and employ it as a photocatalyst for CO2 reduction. Under the protection of GDY, the CsPbBr3-based photocatalyst delivers significantly improved stability in a photocatalytic system containing water concomitant with enhanced CO2 uptake capacity. The favorable energy offset and close contact between CsPbBr3 and GDY trigger swift photogenerated electron transfer from CsPbBr3 to doping metal sites in GDY, boosting a remarkable improvement in the photocatalytic performance for CO2 reduction. Without adding traditional sacrificial reductants, the cobalt-doped photocatalyst achieves a high yield of 27.7 μmol g–1 h–1 for photocatalytic CO2 conversion to CO based on water as a desirable electron source, which is about 8 times higher than that of pristine CsPbBr3 nanocrystals.

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Modulating the morphology and chemical composition is an efficient strategy to enhance the catalytic activity for water splitting, since it is still a great challenge to develop a bifunctional catalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) over a wide pH range. Herein, Pd/ NiFeO x nanosheets are synthesized with tightly arranged petal nanosheets and uniform mesoporous structure on nickel foam (NF). The porous 2D structure yields a larger surface area and exposes more active sites, facilitating water splitting at all pH values. The overpotential of Pd/NiFeO x nanosheets for OER is only 180, 169, and 310 mV in 1 m KOH, 0.5 m H 2 SO 4 , and 1 m phosphate-buffered saline (PBS) conditions at 10 mA cm −2 current density, as well as excellent HER activity with ultralow overpotential in a wide pH range. When using porous Pd/NiFeO x nanosheets as bifunctional catalysts for water splitting, it just required a cell voltage of 1.57 V to reach a current density of 20 mA cm −2 with nearly 100% faradic efficiency in alkaline conditions, which is much lower than that of benchmark Pt/CǁRuO 2 (1.76 V) couples, along with the improving stability benefiting from the good corrosion resistance of the inner NiFeO x nanosheets.

We have firstly demonstrated the photocatalytic utilization of a halide perovskite for combining reduction of CO2 with selective oxidation of methanol.