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Heavy pnictogen chalcohalide semiconductors are coming under the spotlight for energy conversion applications. Here we present the colloidal synthesis of phase pure AgBiSCl2nanocrystals. This quaternary chalcohalide compound features a quasi-two-dimensional crystal structure and a direct band gap, in contrast with the monodimensional structure and the indirect band gap peculiar to the orthorhombic, ternary Bi chalcohalides. Consistently, colloidal AgBiSCl2nanocrystals exhibit photoinduced luminescence compatible with both band edge excitons and midgap states. This is the first observation of band edge emission in chalcohalide nanomaterials at large, although exciton recombination in our AgBiSCl2nanocrystals mostly occurs via nonradiative pathways. This work further advances our knowledge on this class of mixed anion semiconductor nanomaterials and provides a contribution to establishing chalcohalides as a reliable alternative to metal chalcogenides and halides.

This paper describes for the first time the development of novel photocatalytic coatings specifically for medium-density fibreboard (MDF) substrates. Anatase nanostructures were manufactured using a sol–gel synthesis route and subsequently heat-treated to form micro-sized agglomerates. In this study titanium dioxide particles were doped with cobalt in order to reduce the band gap and promote photocatalysis in the visible wavelength range. These agglomerates were then bound to MDF using a polyurethane-based binder. The subsequent coatings were tested under white, green and ultraviolet light using ink intelligent photoactive dyes in a gaseous environment and methylene blue indicator in an aqueous environment. Manufactured particles were also compared to the commercially available products P25 and Kronoclean 7000. The physical and chemical properties of the manufactured particles and substrates were evaluated using electron microscopy, X-ray diffraction and Raman spectroscopy. This work demonstrates the performance of photocatalytic coatings applied to MDF.

Modern life-style is creating an indoor generation: human beings spend approximately 90% of their time indoors, almost 70% of which is at home – this trend is now exacerbated by the lockdowns/restrictions imposed due to the COVID-19 pandemic. That large amount of time spent indoors may have negative consequences on health and well-being. Indeed, poor indoor air quality is linked to a condition known as sick building syndrome. Therefore, breathing the freshest air possible is of outmost importance. Still, due to reduced ventilation rates, indoor air quality can be considerably worse than outdoor. Heating, ventilation, and air conditioning (HVAC), air filtration systems and a well-ventilated space are a partial answer. However, these approaches involve only a physical removal. The photocatalytic mineralization of pollutants into non-hazardous, or at least less dangerous compounds, is a more viable solution for their removal. Titanium dioxide, the archetype photocatalytic material, needs UVA light to be ‘activated’. However, modern household light emitting diode lamps irradiate only in the visible region of the solar spectrum. We show that the surface of titanium dioxide nanoparticles modified with copper oxide(s) and graphene has promise as a viable way to remove gaseous pollutants (benzene and nitrogen oxides) using a common light emitting diode bulb, mimicking real indoor lighting conditions. Titanium dioxide, modified with 1 mol% CuxO and 1 wt% graphene, proved to have a stable photocatalytic degradation rate, three times higher than that of unmodified titania. Materials produced in this research work are thus strong candidates for offering a safer indoor environment.

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