Zeolitic Imidazolate Framework Coated ZnO Nanorods as Molecular Sieving to Improve Selectivity of Formaldehyde Gas Sensor

Zinc oxide (ZnO) and zeolitic imidazolate framework-8 (ZIF–8) core–shell heterostructures were obtained by using the self-template strategy where ZnO nanorods not only act as the template, but also provide Zn²⁺ ions for the formation of ZIF–8 shell. The ZIF–8 shell was uniformly deposited to form ZnO@ZIF–8 nanorods with core–shell heterostructures at 70 °C for 24 h as the optimum reaction time by the hydrothermal synthesis. Transmission electron microscopy (TEM) images revealed that the ZnO@ZIF–8 heterostructures are composed of ZnO as core and ZIF–8 as shell. Nitrogen (N₂) sorption isotherms demonstrated that the as-prepared ZnO@ZIF–8 nanorods are a typical microporous material. Additionally, the ZnO@ZIF–8 nanorods sensor exhibited distinct gas response for reducing gases with different molecule sizes. The selectivity of the ZnO@ZIF–8 nanorods sensor was obviously improved for the detection of formaldehyde owing to the limitation effect of the aperture of ZIF–8 shell. This study demonstrated that semiconductor@MOF core–shell heterostructures may be a novel way to enhance the selectivity of the gas sensing materials

Boosted Photocatalytic Degradation of Atrazine Using Oxygen-Modified g‑C₃N₄: Investigation of the Reactive Oxygen Species Interconversion

Elaborating the specific reactive oxygen species (ROS) involved in the photocatalytic degradation of atrazine (ATZ) is of great significance for elucidating the underlying mechanism. This study provided conclusive evidence that hydroxyl radicals (·OH) were the primary ROS responsible for the efficient photocatalytic degradation of ATZ, thereby questioning the reliability of widely adopted radical quenching techniques in discerning authentic ROS species. As an illustration, oxygen-modified g-C3N4 (OCN) was prepared to counteract the limitations of pristine g-C3N4 (CN). Comparative assessments between CN and OCN revealed a remarkable 10.44-fold improvement in the photocatalytic degradation of ATZ by OCN. This enhancement was ascribed to the increased content of C–O functional groups on the surface of the OCN, which facilitated the conversion of superoxide radicals (·O2–) into hydrogen peroxide (H2O2), subsequently leading to the generation of ·OH. The increased production of ·OH contributed to the efficient dealkylation, dechlorination, and hydroxylation of ATZ. Furthermore, toxicity assessments revealed a significant reduction in ATZ toxicity following its photocatalytic degradation by OCN. This study sheds light on the intricate interconversion of ROS and offers valuable mechanistic insights into the photocatalytic degradation of ATZ

Data-Driven Based In-Depth Interpretation and Inverse Design of Anaerobic Digestion for CH₄‑Rich Biogas Production

Anaerobic digestion (AD) is one of the most widely used bioconversion technologies for renewable energy production from wet biowaste. However, such an AD system is so complicated that it is challenging to fully comprehend this process and design the operational conditions for a specific biowaste to achieve CH4-rich biogas. In this context, ensemble machine learning (ML) algorithms were employed to develop multitask models for jointly predicting the CH4 yield and content in biogas and understanding this complicated process. Based on the best ensemble model with the R2 values of 0.82 and 0.86 for the multitask prediction of CH4 yield and content, the top three critical factors for CH4 yield/contents were identified and their interactions with process acid generation and microbial community in the AD process were comprehensively interpreted to unveil their importance on CH4 generation. Moreover, the well-developed ensemble model was integrated with an optimization algorithm to inversely design the AD process for a real-world food waste, in which the CH4 yield was as high as 468.7 mL/gVS and the calculation results were experimentally validated with relative errors of 9–16%. This work provides a creative approach to gain insights and inverse design for AD reactors, which is helpful to waste-to-energy technologists and practitioners

High-Purity V₂O₅ Nanosheets Synthesized from Gasification Waste: Flexible Energy Storage Devices and Environmental Assessment

Gasification waste, also known as carbon soot, is solid industrial waste from the bottom residual of an oil refinery and contains a substantial amount of toxic vanadium. In this work, we report an environmentally responsible pathway to harvest toxic vanadium from gasification waste, and the extracted vanadium can be utilized to synthesize high-purity V2O5 nanosheets for the fabrication of flexible, bendable, efficient supercapacitors. The carbonaceous waste was first rinsed with alkaline solution to leach out toxic vanadium. The vanadium-rich leachate was next utilized to synthesize high-quality V2O5 crystals with comparable purity (>98%) and crystallinity to commercial products. Two-dimensional V2O5 nanosheets were further crystallized by hydrothermal treatment for the fabrication of high-performance electrochemical electrodes. The V2O5 electrodes derived from gasification waste demonstrated similar specific capacitance (172 F g–1) to those from commercial V2O5 (173 F g–1). The waste-derived V2O5 nanosheets were further mixed with leached carbon nanoparticles for the fabrication of a symmetric, bendable, and flexible supercapacitor. The waste-derived V2O5 supercapacitor was able to be bent up to 160° and retained its specific capacitance. An environmental impact assessment was finally conducted to evaluate the environmental impacts of producing V2O5 crystals from gasification waste (in terms of the damage to human health, ecosystem diversity, and resource availability). The waste-derived approach was compared with traditional mining processes and showed a large improvement in all three endpoint damage categories

High-Purity V₂O₅ Nanosheets Synthesized from Gasification Waste: Flexible Energy Storage Devices and Environmental Assessment

Gasification waste, also known as carbon soot, is solid industrial waste from the bottom residual of an oil refinery and contains a substantial amount of toxic vanadium. In this work, we report an environmentally responsible pathway to harvest toxic vanadium from gasification waste, and the extracted vanadium can be utilized to synthesize high-purity V2O5 nanosheets for the fabrication of flexible, bendable, efficient supercapacitors. The carbonaceous waste was first rinsed with alkaline solution to leach out toxic vanadium. The vanadium-rich leachate was next utilized to synthesize high-quality V2O5 crystals with comparable purity (>98%) and crystallinity to commercial products. Two-dimensional V2O5 nanosheets were further crystallized by hydrothermal treatment for the fabrication of high-performance electrochemical electrodes. The V2O5 electrodes derived from gasification waste demonstrated similar specific capacitance (172 F g–1) to those from commercial V2O5 (173 F g–1). The waste-derived V2O5 nanosheets were further mixed with leached carbon nanoparticles for the fabrication of a symmetric, bendable, and flexible supercapacitor. The waste-derived V2O5 supercapacitor was able to be bent up to 160° and retained its specific capacitance. An environmental impact assessment was finally conducted to evaluate the environmental impacts of producing V2O5 crystals from gasification waste (in terms of the damage to human health, ecosystem diversity, and resource availability). The waste-derived approach was compared with traditional mining processes and showed a large improvement in all three endpoint damage categories