Abstract: (1) Grape stalks and aquafaba (Aq) from chickpeas are promising agricultural by-products with potential applications in the development of sustainable biomaterials due to their ligno-cellulose and protein content. (2) This study aimed to evaluate the incorporation of Aq and cinnamon essential oil (CEO) into grape stalk-based materials to enhance me-chanical properties and prevent microbial contamination. Four formulations were pre-pared, and their mechanical, physicochemical, and antifungal properties were assessed. (3) The incorporation of CEO significantly reduced water absorption, while formulations containing Aq exhibited the highest mechanical resistance, likely due to synergistic interactions between proteins and polysaccharides that modified the microstructure of cellulose fibers. Scanning electron microscopy (SEM) images supported these findings. Additionally, CEO-treated samples showed resistance to fungal contamination by Botrytis cinerea, unlike untreated samples, which were colonized by the fungus. Biodegradability tests indicated slower degradation for CEO-treated samples (10 weeks) compared to those without CEO (5-7 weeks). (4) The results suggest that the combination of Aq and CEO creates a promising material for use in food packaging, though further research is needed to fully understand the reinforcement mechanisms.

Abstract: The research context of this study focuses on optimizing the use of C60 steel in industrial applications where durability and fatigue resistance are critical. C60 steel is known for its combination of strength and hardness, but it is essential to evaluate how thermal and thermo-chemical treatments affect its performance under fatigue condi-tions. The objectives of the study include: Investigating the crack formation process and the early stages of fatigue in C60 steel, comparing the effects of thermal treatments (hardening and tempering) with those of thermo-chemical treatments (oxidation) on the steel's micro-structure, evaluating the performance of C60 steel under fatigue conditions based on the applied treatments, providing insights that can help optimize the use of this steel in in-dustries requiring high resistance and durability. The methodology of the study included: fatigue tests performed on a four-point bending machine to determine the exact time of microcracking. The C60 steel samples were pro-cessed according to SR ISO 1099:2017 "Fatigue testing. Axial load method". To ensure consistency and comparability of results, the samples were made from the same material charge and machined under the same conditions. A total of 26 specimens were used, 13 for each type of treatment: thermal treatment by hardening and tempering and thermo-chemical treatment by oxidation. Due to the different mechanical properties obtained from the thermal and thermo-chemical treatment processes, the sets of specimens were tested at varying forces. In these tests, frequency changes were monitored to evaluate the behaviour of the materials under repeated stresses. Finally, the frequency changes were correlated with the number of cycles to identify when microcracks appeared and their evolution. The main results from this study show: significant differences between the lifetimes of thermally and thermochemically treated samples and the time of microcracks appear-ance in the material.

Abstract: Ferroelectric liquid crystals (FLCs) are key materials for high-speed electro-optical applications, yet achieving optimal properties over a broad temperature range down below room temperature remains a challenge. This study presents a novel series of systematically designed FLC mixtures, incorporating achiral, monochiral, and bichiral components to optimize the mesomorphic stability, electro-optical response, and physicochemical properties. The strategic doping by chiral components up to a 0.2 weight fraction extends the temperature range of the ferroelectric phase while lowering the melting temperature. Notably, mixtures containing two chiral centers exhibit shorter helical pitches, while increasing chirality enhances the tilt angle of the director and spontaneous polarization. However, in the complex chiral mixture (CchM), spontaneous polarization decreases due to opposing vector contributions. Switching time analysis reveals that achiral–bichiral systems exhibit the fastest response, while CchM demonstrates only intermediary behaviour, caused by its high rotational viscosity. Among all formulations, mixtures containing bichiral compounds display the most favorable balance of functional properties for deformed helix ferroelectric liquid crystal (DHFLC) applications. One such composition achieves the lowest melting temperature reported for DHFLC-compatible FLCs, enabling operation at sub-zero temperatures. These findings pave the way for next-generation electro-optical devices with enhanced performance and appropriate environmental stability.

Abstract: Recently, graphene oxide (GO) has been largely investigated as potential adsorbent towards dyes. However, the major obstacle to its fully employment is linked to its nat-ural powder consistence, which greatly complexifies the operations of recovery and reuse. With the aim to overcome this issue, the present work reports the design of GO modified carbon nanotubes buckypapers (BPs), in which the main component, GO, is entirely entrapped in the BP grid generated by CNTs, for the double purpose of a) in-creasing adsorption performance of GO-BPs and b) ensure a fast process of regenera-tion and reuse. Adsorption experiments were performed towards several dyes: Acid Blue 29 (AB29), Crystal Violet (CV), Eosyn Y (EY), Malachite Green (MG), and Rhoda-mine B (RB) (Ci = 50 ppm, pH=6). Results demonstrated that adsorption is strictly de-pendent on the charge occurring both on GO-BP and dye surfaces, observing great ad-sorption capacities towards MG (493.44 mg g-1), RB (467.35 mg g-1) and CV (374.53 mg g-1), due to the best coupling of dye cationic form with negative GO-BP surface. Con-firmed also by kinetic constants, where higher values are those of MG, RB and CV, the following trend in GO-BP adsorption performance has been derived: MG ≈ RB > CV > AB29 > EY.

Abstract: This study examines a new approach for improving the dispersion of hydrophilic fillers into a hydrophobic polymer matrix, a long-standing challenge that often limits the thermal and mechanical performance of biocomposites. We investigated two different types of fillers—natural cellulose nanocrystals (CNC) and mineral calcium carbonate (CaCO₃)—introduced into polylactic acid (PLA) at five different volume fractions. PLA-based biocomposite films were fabricated using physical mixing and cryo-milling methods, followed by hot pressing to study their effects. Cryo-milling was explored as a promising strategy to enhance filler distribution within the matrix. Thermal properties, crystallization behavior, and mechanical performance were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing. CNC addition slightly lowered the glass transition temperature (Tg), while CaCO₃ raised it; both fillers promoted crystallization, although overall crystallinity remained relatively stable. Mechanically, tensile strength and strain decreased with filler addition, but CNC composites, particularly those prepared by cryo-milling, retained better ductility. Both CNC and CaCO₃ increased the modulus of PLA composites, with CaCO₃ providing a greater improvement. Although cryo-milling improved nanoparticle dispersion within the PLA matrix, better interfacial bonding is still needed. Future strategies, such as surface modification of fillers—like PEG-coating CNC—are recommended alongside improved mixing methods to optimize composite performance for sustainable applications.

Abstract: This study explores advancements in photovoltaic technologies by enhancing the optoelectronic properties and electronic quality of multicrystalline Silicon (mc-Si) through silicon nitride (SiNx) and hydrogen (H2) plasma deposition via Plasma-Enhanced Chemical Vapor Deposition (PECVD). This innovative approach replaces toxic chemical wet processes with H2 plasma and SiNx, promoting environmentally friendly and sustainable energy solutions. Key parameters of silicon solar cells, including effective lifetime (τeff), diffusion length (Ldiff), in addition to the iron concentration ([Fe]), were analyzed before and after this sustainable solution. The results show significant improvements, particularly in the edge region, which initially exhibited low τeff and a high iron concentration. After treatment, τeff and Ldiff increased to 7 μs and 210 μm, respectively, compared to 2 μs and 70 μm for untreated mc-Si. Additionally, the [Fe] decreased significantly after the process, dropping from 60 ppt to 10 ppt in most regions. Furthermore, the treatment led to a significant decrease in reflectivity, from 25% to 8% at a wavelength of 500 nm. These findings highlight the effectiveness of PECVD-SiNx and H2 plasma treatments in improving the optoelectronic performance of mc-Si, making them promising for high-efficiency photovoltaic devices.

Abstract: Sustainable EPDM elastomers are gaining traction as eco-friendly sealing materials in fuel cell applications. This study evaluates the mechanical degradation behavior of two ECO EPDM formulations—one reinforced with circular carbon black (CCB EPDM) and the other with recycled carbon black (RCB EPDM)—under conditions representative of acidic fuel cell environments. The samples underwent thermal aging at 90 °C for for 1000 hours and were immersed in aqueous H₂SO₄ solutions of varying concentrations (1 M, 0.1 M, and 0.001 M) for 1000 hours at the same temperature. Gravimetric and volumetric swelling measurements revealed that RCB EPDM experienced significantly higher mass and volume uptake, particularly at intermediate acid concentration, indicating greater susceptibility to fluid ingress. Mechanical testing, including tensile strength, Shore A hardness, and IRHD microhardness, showed that while RCB EPDM exhibited higher initial strength, it degraded more severely under thermal and acidic exposure. SEM-EDS analysis revealed microstructural damage and compositional changes, with RCB EPDM displaying more pronounced oxidation and surface erosion. In contrast, CCB EPDM demonstrated greater retention of mechanical integrity, dimensional stability, and lower variability across aging conditions. These findings highlight the advantages of circular carbon black in enhancing the durability of ECO EPDM compounds in acidic and thermally dynamic fuel cell environments.

Abstract: The London dispersive and polar surface properties of solid materials are very important in many chemical processes, such as adsorption, coatings, catalysis, colloids, and mechanical engineering. One of materials such as styrene–divinylbenzene copolymer modified by 5-hydroxy-6-methyluracil at different percentages, was not deeply characterized in literature, and especially, it is very crucial to determine their London dispersive and polar properties. The new recent research in the inverse gas chromatography (IGC) technique allowed a full determination of the surface properties of styrene–divinylbenzene copolymer modified by 5-hydroxy-6-methyluracil by choosing well-known polar and non-polar organic solvents and varying the temperature. Applying the IGC technique at infinite dilution led to the retention volume of adsorbed molecules on styrene–divinylbenzene copolymer modified by 5-hydroxy-6-methyluracil at different percentages using the Hamieh thermal model and our new recent results on the separation of the two polar and the dispersive contribution of the free energy of interaction. The surface properties of these materials, such the surface free energy of adsorption, the polar acid and base surface energy, and the Lewis acid–base parameters were obtained as a function of temperature and for different percentages 5-hydroxy-6-methyluracil. The obtained results proved that the polar free energy of adsorption on styrene–divinylbenzene copolymer increased when the percentage of 5-hydroxy-6-methyluracil (HMU) increased. However, a decrease of the London dispersive surface energy of copolymer was observed for higher percentage of 5-hydroxy-6-methyluracil. A Lewis amphoteric character was shown for the copolymer with highest acidity, while the basicity linearly increased when the percentage HMU increased.

Abstract: Water pollution by persistent organic and inorganic contaminants implies a significant trouble for ecosystems and public health. Organic substances such as dyes, pharmaceutical residues, pesticides, and phenolic compounds are increasingly detected in water due to industrial and agricultural activities. Alongside these, toxic heavy metals contribute to the complexity of water treatment challenges. Conventional remediation methods often fall short due to high operational costs or limited efficiency. In this context, photocatalysis has emerged as a promising approach for pollutant degradation in water under light irradiation. In this sense, covalent organic frameworks (COFs), a class of porous, crystalline materials formed by covalent linkage of organic units, offer great advantages as photocatalysts. Their tunable electronic properties, structural diversity, and high stability under aqueous conditions make them ideal for visible-light-driven processes. This review explores the structural features that govern the photocatalytic activity of COFs, including conjugation, bandgap modulation, and donor–acceptor structures. Mechanistic insights into photocatalytic degradation are also discussed. Finally, examples of pre-designed COFs are presented with their application in photodegradation of water pollutants and their main reactive oxygen species (ROS) involved in the photodegradation mechanism. Overall, this review aims to provide a foundation for the rational design of COFs in advanced water treatment technologies.

Abstract: The global energy crisis necessitates sustainable and efficient energy alternatives. Dye-sensitized solar cells (DSSCs) represent a promising solution due to their low cost, flexibility, and environmental friendliness. This study focuses on the fabrication and characterization of nanostructured titanium dioxide (TiO₂) thin films using the sol-gel method, employing titanium (IV) isopropoxide and isopropyl alcohol as precursors. A natural dye derived from hen feathers was used as a renewable and eco-friendly sensitizer. The HFD + TiO₂ thin film was analyzed for their surface morphology, optical, structural and photoelectrical properties. Scanning Electron Microscopy (SEM) revealed a uniform distribution of spherical nanoparticles with average particle size 113.93 nm, while X-ray Diffraction (XRD) confirmed the anatase phase of TiO₂ with a crystallite size of 40.12 nm. Optical studies indicated a reduction in the band gap after dye loading, enhancing light absorption and improving DSSC efficiency. Elemental composition and molecular structure were investigated using X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-ray Analysis (EDAX), Fourier Transform Infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy. The hen feather dye-sensitized TiO₂ thin films achieved a photovoltaic conversion efficiency of 2.91%, demonstrating effective light harvesting and favorable electron dynamics. This research underscores the potential of bio-derived materials, such as hen feather dye, in advancing sustainable and cost-effective photovoltaic technologies. These findings promote circular economy principles by utilizing waste-derived resources for green energy solutions.

Abstract: Chitosan biopolymer membranes reinforced with channel-selective ZIF-8 nanofillers were developed and characterized for use as separators in bioelectrochemical systems. The study focused on the application of biopolymer chitosan in combination with ZIF-8 as nano reinforcement agents to improve membrane performance. Key properties such as water retention, chemical and thermal stability, surface resistance, antifouling ability, and ionic conductivity of the mixed matrix membranes (Composite ZIF-8/chitosan) were evaluated and compared with commercial Nafion-117 and nanofiltration (NF) membranes. The composite ZIF-8/chitosan membranes exhibited excellent water retention and structural stability under harsh conditions, while reducing surface resistance and effectively rejecting organic contaminants and salts (NaCl, Na₂SO₄). Impressively, the ionic conductivity reached 0.105 S/cm, which is similar to that of Nafion-117. These results suggest that biopolymer chitosan reinforced with ZIF-8 nanofillers offers a sustainable and cost-effective alternative for use as separators in bioelectrochemical systems applications.

Abstract: The use of thermochromic pigments in food packaging offers several advantages, including improved food safety, waste reduction, and temperature change monitoring. However, little is known about how chemically resilient these materials are, especially regarding optical stability, thermochromic activation, and mechanical integrity following exposure to acidic, alkaline, oil-based, and neutral food-contact environments. This study evaluates the chemical resistance, thermal cycling effects, and mechanical durability of thermochromic pigments-polymer blends. Thermochromic polymer samples were subjected to multiple chemical environments, repeated thermal cycling, and mechanical analysis to assess degradation behavior. The findings show that virgin food-grade polymer with no thermochromic pigment sustains its performance stability throughout chemical exposure with little degradation. However, thermochromic polymer blends experienced reduced thermochromic functionality. This study offers insight into how well thermochromic pigment can be incorporated into intelligent food packaging despite the limitations associated with chemical exposure.

Abstract: The construction sector is heading towards more sustainable practices by focusing on the utilization of secondary materials previously considered waste. Among these materials, cellulose and mining and metallurgy slags are particularly significant due to their prevalence and the volume of waste they represent. These materials are generated in vast quantities globally, posing environmental challenges but also presenting substantial opportunities for reuse in construction, thereby reducing landfill use and promoting resource efficiency. Additionally, the reuse of cellulose and slag has a substantial environmental impact. Transforming them into valuable construction resources can significantly reduce the environmental footprint associated with extracting and processing new raw materials. This reuse not only mitigates waste but also aligns with global sustainability goals by lowering emissions and reducing resource depletion. The growing use of cellulose in products like insulation and fiberboards, and the incorporation of slags into concrete and road materials, underscores the feasibility of these practices. Despite these promising developments, challenges such as economic feasibility, technological limitations, and regulatory issues continue to limit their full potential. This review explores these challenges and provides an in-depth look at the innovations and strategies needed to overcome them, setting a path for a sustainable and circular construction industry.

Abstract: In Part 1 of this work, it concerns about theoretical foundation of microwave absorption theories that the newly established wave mechanics theory conforms to transmission line theory while the impedance matching theory of microwave absorption originates from the misinterpretation of this fundamental physics law. This Part 2 provides another perspective from a question and its responses from DeeoSeek to show the common mis-concepts dominated in the field. The purpose of the work is to draw attention of the material scientists to the important issues concerned since the practice of wrong theories continuing in publication with little attention to the newly established wave mechanics theory for microwave absorption. It also shows that artificial intelligence can be a useful tool to identify how the established concepts were behind the scenes to prevent the wave mechanics theory from to be accepted, even though machine intelligence cannot go beyond commonly accepted theory to provide innovations.

Abstract: Nickel phosphides (Ni_xP_y) are recognized as an important potential alternative to noble-metal catalysts for the oxygen evolution reaction (OER). Among nickel phosphides, NiP consisting of the equal stoichiometric ratio of Ni and P could help quantify the catalytic effect of P and Ni. In this work, density functional theory (DFT) is employed to investigate the OER mechanism of NiP surfaces. Electronic structure theory analysis reveals that P atoms tend to assist in stabilizing O* at the adsorption sites. The rich electron donation from the Ni atom can alter the local charge distribution and enhance the interaction between O* and P atom. Moreover, we find that both oxygen intermediate adsorption energy and OER overpotential exhibit linear correlations with adsorption site charge. Electron loss at the site induces the overall system exhibiting Lewis acid characteristics, making it favorable for the OER. Leveraging electronic structure theory and Lewis acid-base theory, we offer a new insight into the OER mechanism on NiP surface, demonstrating that the catalytic activity of bulk metallic surface materials like NiP can be optimized by tailoring the local chemical environment on the surface. This study may provide a reference for base metal catalyst design.

Abstract: The production and development of drug-loaded nanofibers by electrospinning are interesting because of their use as scaffolds in drug-delivery system applications. In the present study, Preparing the 50:50 polylactic acid: Gelatin and ZnO nanoparticles (PLA: GA: ZnO) scaffold nanofibers for loading the anti-inflammatory drugs naproxen and meloxicam at 0.1, 0.2, and 0.3 wt. % of each drug. The morphology results measured by scanning electron microscopy showed significantly increased diameters by 556±427, 566±437, and 1298±723 nm for 0.1%, 0.2%, and 0.3wt.% for naproxen, respectively compared with 352±245 nm for PLA: GA: ZnO. While the meloxicam revealed nanofibers with smaller diameters; the respective diameters for the ratios 0.1%, 0.2%, and 0.3% were 327 ± 163 nm, 312 ± 156 nm, and 333 ± 209 nm. Zinc oxide increases the crystal size, while the loaded drugs improve the degree of crystallization. Consequently, the fibers turn into a low-crystalline structure. FTIR spectroscopy results indicated no chemical interaction between the polymers. Moreover, adding zinc oxide nanoparticles to the blend polymer fibers increased the surface's free energy by 56.31±1.69 mJ.m-2 and reduced the contact angle to 83.16 ± 2.49°. Conversely, both naproxen and meloxicam increased the contact angle and reduced the surface's free energy, reaching values of 116.14 ± 3.48°, 114.4 ± 3.43°, 37.05±1.11 mJ.m-2, and 38.78±1.16 mJ.m-2 In addition, the drugs accelerate the thermal degradation of the polymer matrix. The maximum cumulative release for drug samples at 21 days was 97.62±4.88%, and 93.75±4.53 % for NAP and MEL respectively, while 87.24±4.24% for PLA: GA: ZnO. The kinetic model for samples showed the Korsmeyer-Peppas more suitable in this study, the burst release of 60.66% and 55.67% drugs from NAP and MEL Nano fibrous formulations was observed during the first 24 h. The diffusion coefficient (n) values of all nanofiber samples were found to be n < 0.45, confirming that the drug release mechanism follows Fickian diffusion. Naproxen produced a diameter of inhibition zones (MIC) at a stuck solution (MIC1000) of 17± 3.7 mm against S. aureus and 16±3.1 mm against E. coli, while meloxicam showed MIC1000 of 18±3.4 mm and 17±3.7 mm against S. aureus and E. coli, respectively. All dilution ratios of the drug solutions showed antibacterial activity. All samples showed no cytotoxicity, with cell viability ranging from 81% to 98.5%, confirming their biocompatibility. In addition, the naproxen showed the low half-maximal inhibitory concentration (IC50) value indicates that the drug is effective at low concentrations. The statistical analysis of all samples (P< 0.05)

Abstract: This paper presents the results of a study of the effect of a biochar additive produced by pyrolysis at 400^oC and 500^oC from waste biomass, i.e. walnut shells, on the tribological and rheological properties of vegetable lubricating compositions. Sunflower oil, and amorphous silica as a thickener were used to prepare the lubricants. To the base lubricant prepared in this way, 1 and 5 % of biochar additive was introduced and, for comparison, take the same amounts of graphite. Tests were carried out on the anti-wear properties, coefficient of friction and changes in dynamic viscosity during the tribological test, as well as on the anti-scuffing properties for the tested lubricant compositions. The effect of the applied modifying additive on the lubricating and rheological properties of the prepared lubricating greases was evaluated. On the basis of the study of vegetable greases, it was found that the addition of 5% biochar from walnuts shell produced during pyrolysis in 500^oC had the most favourable effect on the anti-wear properties of the tested greases, while the 5% of biochar from walnuts shell prepared in pyrolysis in 400^oC had the best antiscuffing protection. The use of the biochar additive in vegetable greases resulted in a reduction in the dynamic viscosity of the tested greases, particularly for greases modified with 5% of walnut shell biochar produced at 500^oC, which is particularly important during the work of steel friction nodes and in central lubrication systems.

Abstract: In this paper the modification of natural clinoptilolite and mordenite zeolites from Almaty using acid treatment is addressed for the purposes of improving adsorption performance and for drinking water purification. Structural chemical transformation was characterized by the use of XRD, FTIR, and SEM techniques. Acid treatment led to a partial dealumination that was responsible for the increase in number of surface defects and micropores, improvement in ion exchange capacity and selectivity toward heavy metals. Additionally, modifications greatly enhance the uptake capacities of Pb²⁺, Cd²⁺ and As³⁺. The clinoptilolite post-modification removal efficiencies reached 94%, 86%, and 84% respectively, while mordenite zeolites achieved 95%, 90%, and 87% removal efficiencies respectively. The enhancement of performance was related to the increase of surface area and active sites for ion exchange, verified from analysis of BET surface area. The use of different Bhatt and Kothari methods has revealed that adsorption processes followed Langmuir isotherm models for Pb²⁺ and Cd²⁺, whereas As³⁺ adsorption was better described by the Freundlich isotherm model. However, second-order kinetics indicate that chemisorption was the dominant mechanism. Such evidence indicates spontaneity and an endothermic process, as shown from thermodynamic studies. Results showed that modified zeolites indeed had a high degree of reusability, with over 80% of the adsorption capacity retained even after five cycles. Acid-modified zeolites can provide cheaper, greener methods of purification, generating only negligible secondary waste when compare to conventional methods of water purification, for example, activated carbon and membrane filtration. Results from this study proved that modified clinoptilolite and mordenite zeolites have the potential for sustainable heavy metal treatment in drinking water purification systems.

Abstract: This study explores the development of flexible and efficient piezoelectric materials by incorporating multiwalled carbon nanotubes (MWCNTs) into poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] polymer films. The MWCNTs, acting as nucleating agents, significantly improve the electroactive β phase content in the polymer, enhancing its piezoelectric performance. Composite films were prepared using a solution casting technique with varying MWCNTs concentrations (0.25%, 0.5%, 0.75%, and 1.0%). Morphological analysis through SEM and AFM confirmed increased surface roughness and pore size with higher MWCNTs content, resulting in better hydrophobic, mechanical and electrical properties. It is evident that the WCA values of all samples ranged from 96.73° ± 4.82° to 117.07° ± 2.10°, confirming the inherent hydrophobicity of the films and demonstrating good water repellence. FTIR and XRD analyses showed a phase transformation from the non-polar α phase to the polar β phase, enhancing the piezoelectric effect. With increasing MWCNTs content, the crystallinity of the composite improves, rising from 50.04% in the pure P(VDF-HFP) sample to 54.83% in the 1.00% MWCNTs composite, leading to more ordered structures. This boosts the mechanical properties, notably raising the tensile strength from 14.56 MPa to 45.13 MPa. TGA analysis further shows that the composites have higher thermal stability compared to pure P(VDF-HFP), due to increased crystallinity and stronger intermolecular forces. Dielectric measurements showed enhanced dielectric constant and reduced energy loss with increasing MWCNTs concentrations. This finding is pivotal in understanding the piezoelectricity mechanisms within these composites. Finally, piezoelectric sensitivity tests demonstrated an optimal concentration of 0.75% MWCNTs, achieving a voltage output of 16.58 V under applied mechanical stress, making these composites promising candidates for advanced sensing technologies.

Abstract: We present a chemiresistor sensor for NO2 leaks. The sensor uses the organometallic semiconductor copper(II)phthalocyanine (CuPc) and is manufactured and characterised easier than previously described organic transistor gas sensors. Resistance R is high but within range of modern voltage buffers. The chemiresistor weakly responds to several gases, with either a small increase (NH3, H2S), or decrease (SO2) of R. However, response is low at environmental pollution levels. Response to NO2 also is near- zero for permitted long-term exposure. Our sensor is therefore not suited for environmental monitoring, but acceptable environmental pollutant levels also do not interfere with the sensor. Above a threshold of ~ 87 ppb, response to NO2 becomes very strong. Response presumably is due to doping of CuPc by the strongly oxidising NO2, and is far stronger than for previously reported CuPc chemiresistors. We relate this to differences in film morphology. Under 1 ppm NO2, R drops by a factor of 870 vs. non- polluted air. 1 ppm NO2 is far above ‘background’ environmental pollution, avoiding false alarms, but far below immediately life-threatening levels, giving time to evacuate. Our sensor is destined for leak detection in the nitrogen fertiliser industry, where NO2 is an important intermediate.