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The imperative development of a cutting-edge environmental gas sensor is essential to proficiently monitor and detect hazardous gases, ensuring comprehensive safety and awareness. Nanostructures developed from metal oxides are emerging as promising candidates for achieving superior performance in gas sensors. NO2 is one of the toxic gases that affects people as well as the environment so its detection is crucial. The present study investigates the gas sensing capability of copper oxide-based sensor for 5 ppm of NO2 gas at 100 °C. The sensing material was synthesized using a facile precipitation method and characterized by XRD, FE-SEM, UV–visible spectroscopy, photoluminescence spectroscopy, XPS and BET techniques. The developed material shows a response equal to 67.1% at optimal temperature towards 5 ppm NO2 gas. The sensor demonstrated an impressive detection limit of 300 ppb, along with a commendable percentage response of 5.2%. Under optimized conditions, the synthesized material demonstrated its high selectivity, as evidenced by the highest percentage response recorded for NO2 gas among NO2, NH3, CO, CO2 and H2S. [ABSTRACT FROM AUTHOR]

The goal of the current research was to develop CuO-ZnO heterojunction capable of detecting NO2 gas at room temperature. Pure CuO and CuO-ZnO composite samples were developed by changing the weight percentage of CuO and ZnO using a simple precipitation method and nominated as CZ0, CZ1, CZ2 and CZ3. Structural, optical and morphological properties of pristine CuO and heterojunctions were studied using XRD, FE-SEM, BET, XPS, FTIR and PL. Investigation of gas sensing properties revealed that the CZ2 sample (20 wt% ZnO) exhibited maximum response of 36.7% to 100 ppm of NO2 gas at room temperature. The mechanism behind the response of pristine material and CuO-ZnO was explained in detail. The development of p-n heterojunction due to the combination of p-type CuO and n-type ZnO was responsible for the increase in the gas detecting capabilities of the synthesized composite material for detecting NO2 gas at ambient temperature. Hence, the proposed approach focuses on the design of a cost-effective and sensitive gas sensor that can sense NO2 gas even at room temperature. [ABSTRACT FROM AUTHOR]

Energy, water, and healthy air are the basic needs to survive, and all these resources are intricately connected. Modern lifestyle activities and growing energy demands cause more consumption of fossil fuels and contamination of water and air. The inappropriate discharge of a substantial biomass waste byproduct worsened these problems, mainly in developing nations. The carbonization process can resolve all these problems by converting biomass waste into valuable advanced materials. One of the innovative materials is porous activated carbons derived from various biomass and widely utilized as adsorbents of many pollutants and robust energy storage in supercapacitors with a reported specific capacitance of up to 720 F g−1. The highest adsorption capacity of ~ 2600 mg g−1 for contaminants was attained using biomass-derived activated carbon with > 99% removal efficiency and a high surface area of ~ 3700 m2 g−1. In this, the review not only summarizes the most advanced progress in biomass-derived activated carbon and its role in waste water treatment, energy storage, and air purification but also focuses on the essential factors that affect efficiency towards these specific applications for future demands. [ABSTRACT FROM AUTHOR]

The circular economy requires advanced methods to recycle biomass into value-added materials, such as lignin extraction and modification. Here, we review lignin valorization with focus on lignin extraction from biomass, lignin modification, and applications in medicine, cosmetics, environment and agriculture. Lignin extraction can be done by alkaline hydrolysis, kraft pulp method, glycerolysis, single and binary solvent systems, and ionic liquids. Lignin modification includes functionalization, preparation of lignin graft polymers and lignin nanoparticles, and depolymerization. Applications comprise tissue engineering and wound healing, substance carriers for delivery, coatings, natural sunscreen and surfactants. [ABSTRACT FROM AUTHOR]