Construction of bismuth oxide iodide (BiOI)/zinc titanium oxide (Zn2TiO4) p-n heterojunction nanofibers with abundant oxygen vacancies for improving photocatalytic carbon dioxide reduction

Unveiling cutting-edge developments in defective BiOI nanomaterials: Precise manipulation and improved functionalities towards bolstered photocatalysis

Defect engineering represents a paradigm shift in tailoring nanomaterials for enhanced catalytic performance across various applications. This manuscript succinctly highlights the significance of defect engineering in improving the catalytic performance of BiOI nanoparticles for multiple applications, particularly in photocatalysis. The photocatalytic process of BiOI semiconductor is intricately linked to its indirect bandgap and layered crystalline structure. By influencing the structural dynamics of its layered materials, defects contribute significantly to optimizing its catalytic performance. "Fundamental insights into manipulating defects, including oxygen and iodine vacancies, bismuth defects, and synergistic dual defects, in BiOI are meticulously discussed. Advanced characterization techniques, spanning spectroscopy to microscopy, are explored for precise defect identification and quantification. The fragile van der Waals forces foster interactions between adjacent iodine atoms in BiOI, contributing to the overall structural stability". Understanding these structural intricacies lays a robust foundation for comprehending and exploring the exceptional physicochemical properties of two-dimensional BiOI. The manuscript showcases BiOI potential in energy and environmental sectors, ranging from solar-driven H2 evolution to CO2 reduction and various harmful pollutant degradation. By unravelling the intricate interplay between defects and catalytic activity, this manuscript sets a new benchmark for tailored catalytic solutions. This manuscript offers a comprehensive overview of defect engineering in BiOI and charts a path towards sustainable and efficient photocatalytic systems. It underscores the imperative of meticulous defect control and innovation in addressing the pressing challenges of the energy and environmental landscape.

Accelerating carrier separation to boost the photocatalytic CO2 reduction performance of ternary heterojunction Ag-Ti3C2Tx/ZnO catalysts

Developing low-cost and efficient photocatalyst/co-catalyst systems that promote CO2 reduction remains a challenge. In this work, Ag-Ti3C2Tx composites were made using a self-reduction technique, and unique Ag-Ti3C2Tx/ZnO ternary heterojunction structure photocatalysts were created using an electrostatic self-assembly process. The photocatalyst's close-contact heterogeneous interface increases photogenerated carrier migration efficiency. The combination of Ti3C2Tx and Ag improves the adsorption active sites and reaction centers for ZnO, making it a key site for CO2 adsorption and activation. The best photocatalysts had CO and CH4 reduction efficiencies of 11.985 and 0.768 μmol g-1 h-1, respectively. The CO2 conversion was 3.35 times better than that of pure ZnO, which demonstrated remarkable stability even after four cycle trials with no sacrificial agent. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) and valence band spectroscopy were utilized to propose the photocatalytic reaction mechanism and electron transfer channels of the Ag-Ti3C2Tx/ZnO system, confirming that CHO* and CO* are the important intermediates in the generation of CH4 and CO. This study introduces a novel method for the development of new and efficient photocatalysts and reveals that Ti3C2Tx MXene is a viable co-catalyst for applications.

SiO2-TiO2 Nanoparticle Aqueous Foam for Volatile Organic Compounds' Suppression

Volatile organic compounds (VOCs) are prevalent soil contaminants. During the ex situ soil remediation process, VOCs may overflow from the soil and cause gas to diffuse into the atmosphere. Moreover, some VOCs, such as trichloromethane, are categorized by the EPA as emerging contaminants, imparting toxicity to organs, and the endocrine and immune systems, and posing a huge threat to human health and the environment. To reduce VOCs' emissions from contaminated soil, aqueous foam suppression is a prospective method that provides a durable mass transfer barrier for VOCs, and it has been widely used in odor control. Based on an aqueous foam substrate, in order to enhance the foam's stability and efficiency of suppression, SiO2-TiO2-modified nanoparticles have been used as stabilizing agents to improve the mechanical strength of liquid film. The nanoparticles are endowed with the ability to photocatalyze after the introduction of titanium dioxide. From SEM imaging, IR, and a series of morphological characterization experiments, the dispersibility of the SiO2-TiO2-modified nanoparticles was significantly improved under the polar solvent, which, in turn, increased the foam duration. The foam dynamic analysis experiments showed that the foam liquid half-life was increased by 4.08 h, and the volume half-life was increased by 4.44 h after adding the novel synthesized nanoparticles to the bulk foam substrate. From the foam VOC suppression test, foam with modified nanoparticles was more efficient in terms of VOCs' suppression, in contrast with its nanoparticle-free counterparts, due to the longer retention time. Moreover, in a bench-scale experiment, the SiO2-TiO2 nanoparticles foam worked against dichloroethane, n-hexane, and toluene for almost 12 h, with a 90% suppression rate, under UV irradiation, which was 2~6 h longer than that of UV-free SiO2-TiO2 nanoparticles, the KH-570-modified nanosilica foam, and the nanoparticle-free bulk foam. XPS and XRD results indicate that in SiO2-TiO2 nanoparticles, the proportion of titanium valence was changed, providing more oxygen vacancies compared to raw titanium dioxides.