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This study aims to investigate the correlation of the photocatalytic oxidation effect of decomposing organic matter and inactivating bacteria using two different TiO2 materials: a Degussa P25 powder film and a commercial TiO2 thin film. The destructed organic matter was formaldehyde and the test bacterium was E. coli (JM 109 strain). The decomposition tests and the bactericidal tests were carried out in a plate reactor and on the TiO2 surface, respectively. Observations indicate that there exists an apparent correlation between the two photocatalytic processes of decomposing formaldehyde and inactivating E. coli. However, it is essential to distinguish the exact driver for microbe inactivation, in which both UV light irradiation and reactive oxygen species reaction are directfactors of disinfection, and for organic matter, in which only reactive oxygen species reaction contributes to degradation. Observations from this study would make it possible to use analogy as a potential method to evaluate the antimicrobial effect based on the organic compound degradation effect, whereby the latter is much easier to measure quantitatively.

Magnetic van der Waals (vdW) materials possess versatile spin configurations stabilized in reduced dimensions. One magnetic order is the interlayer antiferromagnetism in A-type vdW antiferromagnet, which may be effectively modified by the magnetic field, stacking order and thickness scaling. However, atomically revealing the interlayer spin orientation in the vdW antiferromagnet is highly challenging, because most of the material candidates exhibit an insulating ground state or instability in ambient conditions. Here, we report the layer-dependent interlayer antiferromagnetic spin reorientation in air-stable semiconductor CrSBr using magnetotransport characterization and firstprinciples calculations. We reveal an odd-even layer effect of interlayer spin reorientation, which originates from the competitions among interlayer exchange, magnetic anisotropy energy and extra Zeeman energy of uncompensated magnetization. Furthermore, we quantitatively constructed the layer-dependent magnetic phase diagram with the help of a linear-chain model.Our work uncovers the layer-dependent interlayer antiferromagnetic spin reorientation engineered by magnetic field in the air-stable semiconductor.

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Ultraviolet (UV) light irradiation, including the type of light source, light intensity, and irradiation dosage, directly affects the photocatalytic reaction rate and energy consumption. In this study, we investigated the photocatalysis effect of decomposing organic matter and inactivation bacteria and fungi under various conditions of UV sources (UVA and UVC) and light intensities (from 0.01 to 10 W/m2). The effect of light intensity was evaluated by photocatalytic reaction rate and UV dosage defined as a product of light intensity and irradiation time necessary to achieve a certain reduction. The results confirmed the positive effect of increased light intensity on photocatalytic reactions and suggested that within the light intensity range applied in this study low light intensity with long exposure time has higher light utilization efficiency compared to that of high light intensity with short exposure time. A conception for selection of the appropriate light intensity and dosage for effective degradation of pollutants, while saving energy, was provided.