Abstract: Two electrochemical methodologies, i.e. flowchart and dual-sensor, were developed to aid law enforcement present at festivals to obtain a rapid indication of the presence of four illicit drugs in suspicious samples encountered.

Abstract: The hydrogen evolution properties of CZTS heterostructure photocathodes are reported with graphene oxide (GO) as a co-catalyst layer coated by a drop-cast method and an Al2O3 protection layer fabricated using atomic layer deposition. In the CZTS absorber, a minor deviation from stoichiometry across the cross section of the thin film results in nanoscale growth of spurious phases, but the kesterite phase remains the dominant phase. We have investigated the band alignment parameters such as the band gap, work function, and Fermi level position that are crucial for making kesterite-based heterostructure devices. The photocurrent density in the photocathode CZTS/CdS/ZnO is found to be improved to -4.71 mAmiddotcm(-2) at -0.40 V-RHE, which is 3 times that of the pure CZTS. This enhanced photoresponse can be attributed to faster carrier separation at p-n junction regions driven by upward band bending at CZTS grain boundaries and the ZnO layer. GO as a co-catalyst over the heterostructure photocathode significantly improves the photocurrent density to -6.14 mAmiddotcm(-2) at -0.40 V-RHE by effective charge migration in the CZTS/CdS/ZnO/GO configuration, but the onset potential shifts only after application of the Al2O3 protection layer. Significant photocurrents of -29 mAmiddotcm(-2) at -0.40 V-RHE and -8 mAmiddotcm(-2) at 0 V-RHE are observed, with an onset potential of 0.7 V-RHE in CZTS/CdS/ZnO/GO/Al2O3. The heterostructure configuration and the GO co-catalyst reduce the charge-transfer resistance, while the Al2O3 top layer provides a stable photocurrent for a prolonged time (similar to 16 h). The GO co-catalyst increases the flat band potential from 0.26 to 0.46 V-RHE in CZTS/CdS/ZnO/GO, which supports the bias-induced band bending at the electrolyte-electrode interface.

Abstract: Our economy drives on reactive nitrogen (Nr); while Nr emissions to the environment surpass the planetary boundary. Increasingly, it is advocated to recover Nr contained in waste streams and to reuse it ‘directly’ in the agri-food chain. Alternatively, Nr in waste streams may be removed as N2 and refixed via the Haber-Bosch process in an ‘indirect’ reuse loop. As a systematic sustainability analysis of ‘direct’ Nr reuse and its comparison to the ‘indirect’ reuse loop is lacking, this structured review aimed to analyze literature determining the environmental and economic sustainability of Nr recovery technologies. Bibliometric records were queried from 2000 to 2020 using Boolean search strings, and manual text coding. In total, 63 studies were selected for the review. Results suggest that ‘direct’ Nr reuse using Nr recovery technologies is the preferred paradigm as the majority of studies concluded that it is sustainable or that it can be sustainable depending on technological assumptions and other scenario variables. Only 17 studies compared the ‘direct’ with the ‘indirect’ Nr reuse route, therefore a system perspective in Nr recovery sustainability assessments should be more widely adopted. Furthermore, Nr reuse should also be analyzed in the context of a ‘new Nr economy’ that relies on decentralized Nr production from renewable energy. It is also recommended that on-par technology readiness level comparisons should be carried out, making use of technology development and technology learning methodologies. Finally, by-products of Nr recovery are important to be accounted for as they are reducing the environmental burdens through avoided impacts.

Abstract: Doping two single transition-metal (TM) atoms on a substrate host opens numerous possibilities for catalyst design. However, what if the substrate contains more than one vacancy site? Then, the combination of two TMs along with their distribution patterns becomes a design parameter potentially complementary to the substrate itself and the bimetal composition. In this study, we investigate ammonia synthesis under mild electrocatalytic conditions on a transition-metal-doped porous C24N24 catalyst using density functional theory (DFT). The TMs studied include Ti, Mn, and Cu in a 2:4 dopant ratio (Ti2Mn4@C24N24 and Ti2Cu4@N-24(24)). Our computations show that a single Ti atom in both catalysts exhibits the highest selectivity for N-2 fixation at ambient conditions. This work is a good theoretical model to establish the structure-activity relationship, and the knowledge earned from the metal-N-4 moieties may help studies of related nanomaterials, especially those with curved structures.

Abstract: Despite substantial policy efforts made by the French government to reduce dependence on pesticides, farming practices are only changing slowly. This paper analyses the socio-economic trade-offs that 110 farmers are currently facing in the transition to agro-ecological practices. A mixed-method approach – a quantitative discrete choice experiment (DCE) and qualitative interviews – was set up to understand these farmers' motivations and perspectives, and how policy can improve to accompany them on the road to low chemical input farming. Results of the DCE indicate that the majority of the farmers in our sample are keen to change practices but are at a loss as to how this can be done, as a number of preferences for this transition came out as inconclusive. Qualitative interviews with a representative sample of the farmers that took part in the DCE complemented this result by illustrating a deep uncertainty for the future and a disconnect felt between authorities and themselves as a group. We argue that this uncertainty contributed to a lack of clear-cut solutions established through the DCE. The indepth discussions with farmers illustrated the wish for concrete and local policy measures based on farmers' networks and peer support.

Abstract: Clathrate hydrates gained significant attention as a viable option for large-scale storage of natural gas, primarily methane (CH4). Unlike employing the nanoconfinement for enhancing the nucleation sites and hydrate growth as in the porous materials, whose synthesis is often associated with high costs and poor batch reproducibility, a new approach for promoting CH4 hydrates using pure water (H2O) in an unstirred reactor packed with stainless steel beads (SSB) was proposed in this fundamental work, where the interstitial space between the beads was exploited for enhanced hydrate growth. SSB of two diameters, 5 mm and 2 mm, were used as. a packed bed to investigate their effects on CH4 hydrate formation at 273.65 K, 275.65 K, and 277.65 K with an initial pressure of 6 MPa. The thermal conductivity of SSB packing potentially aided hydrate growth by expelling the hydration heat, while, the results also revealed that driving force has a substantial impact on the rate of CH4 hydrate formation and gas uptake. The experiments conducted in both 5 mm and 2 mm SSB packed bed reactors showed a maximum gas uptake of 0.147 mol CH4/mol H2O at 273.65 K with water to hydrate conversion of 84.42% with no significant variation. The results established the promotion effect on the kinetics of CH4 hydrate formation in the unstirred reactor packed with 2 mm SSB due to the availability of more interstitial space offering multiple nucleation sites for CH4 hydrate by providing a larger specific surface area for H2O-CH4 reaction. Experiments with varying H2O content were also performed and the results showed that the water to hydrate conversion and rate of hydrate formation could be enhanced at a lower H2O content in a packed bed reactor. This study demonstrates that the use of costly or intricate porous materials can be made redundant, by exploiting the interstitial voids in packing of cheap and widely available SSB as a promising alternative material for enhancing the kinetics of artificial CH4 hydrate synthesis.

Abstract: In this work, the absorption–desorption performance of CO2 in six new solvent blends of amine (diisopropylamine (DPA), 2-amino-2-methyl-1-propanol (AMP), methyldiethanolamine (MDEA), diethanolamine (DEA), diisopropanolamine (DIPA), and ethanolamine (MEA)), sulfolane, and methanol has been monitored using ATR-FTIR spectroscopy. Additionally, NMR-based species confirmation and solvent viscosity analysis were done for DPA solvent samples. The identified CO2 capture products are monomethyl carbonate (MMC), carbamate, carbonate, and bicarbonate anions in different ratios. The DPA solvent formed MMC entirely with 0.88 molCO2/molamine capture capacity, 0.48 molCO2/molamine cyclic capacity, and 3.28 mPa·s CO2-loaded solvent viscosity. MEA, DEA, DIPA, and MDEA were shown to produce a low or a negligible amount of MMC while AMP occupied an intermediate position.

Abstract: Electrophoretic Deposition (EPD) is one of the alternative methods to fabricate and enhance the performance of Li-ion batteries. It enables the fabrication of electrodes with outstanding qualities and different electrochemical properties by the great domination over various parameters. EPD facilitates the processing of electrodes by binder-free grafting of nanomaterials, such as graphene derivatives, carbon nanotube, and nanoparticles, into the battery electrodes. It also enables the assembly of the free-standing electrodes with 3D structure and provides possibilities, such as the fabrication of the electrodes with an oriented microstructure, even on 3D substrates to improve the energy or power density. In this review, after an introduction to EPD, the effect of EPD parameters on the properties of the prepared electrodes is reviewed. Then, EPD is compared with tape cast, and its advantages over the conventional method are evaluated. Also, employing the EPD method as an intermediate process is discussed. Finally, the application of EPD in the fabrication of separators is assessed, and the prospects for the future are described.

Abstract: The microstructural features of intergranular irradiation-assisted stress corrosion crack tips from a redeemed neutron-irradiated flux thimble tube (60 dpa) have been investigated using focused-ion beam analysis and (scanning) transmission electron microscopy. The current work presents a close examination of the deformation field and oxide assembly associated with intergranular cracking, in addition to the analysis of radiation-induced segregation at leading grain boundaries. Evidence of stress induced martensitic transformation extending from the crack tips is presented. Intergranular crack arrest is demonstrated on the account of the external tensile stress orientation, and as a consequence of MnS inclusion particles segregating close to the fractured grain boundary. Exclusive observations of grain boundary oxidation prior to the cracking are presented, which is in full-agreement with the internal oxidation model.(c) 2022 Elsevier B.V. All rights reserved.

Abstract: A combination of synchrotron radiation-based elementalimaging, in vivo redox status analysis, histology, and toxic responses was usedto investigate the uptake, biodistribution, and adverse effects of Cenanoparticles (CeO2NP; 10 nm; 0.5-34.96 mg Ce L-1) or Ce(NO3)3(2.3-26 mg Ce L-1)inCaenorhabditis elegans. Elemental mapping of theexposed nematodes revealed Ce uptake in the alimentary canal prior todepuration. Retention of CeO2NPs was low compared to that of Ce(NO3)3in depurated individuals. X-rayfluorescence (XRF) mapping showed that Cetranslocation was confined to the pharyngeal valve and foregut. Ce(NO3)3exposure significantly decreased growth, fertility, and reproduction, causedslightly reduced fecundity. XRF mapping and histological analysis revealedsevere tissue deformities colocalized with retained Ce surrounding thepharyngeal valve. Both forms of Ce activated the sod-1 antioxidant defense,particularly in the pharynx, whereas no significant effects on the cellular redox balance were identified. The CeO2NP-induceddeformities did not appear to impair the pharyngeal function or feeding ability as growth effects were restricted to Ce(NO3)3exposure. The results demonstrate the utility of integrated submicron-resolution SR-based XRF elemental mapping of tissue-specificdistribution and adverse effect analysis to obtain robust toxicological evaluations of metal-containing contaminants.

Abstract: This study aims at sensing in situ reactive oxygen and nitrogen species (RONS) and specifically superoxide anion (O-2(center dot-)) in aqueous buffer solutions exposed to cold atmospheric plasmas (CAPs). CAPs were generated by ionizing He gas shielded with variable N-2/O-2 mixtures. Thanks to ultramicroelectrodes protected against the high electric fields transported by the ionization waves of CAPs, the production of superoxide and several RONS was electrochemically directly detected in liquids during their plasma exposure. Complementarily, optical emissive spectroscopy (OES) was used to study the plasma phase composition and its correlation with the chemistry in the exposed liquid. The specific production of O-2(center dot-), a biologically reactive redox species, was analyzed by cyclic voltammetry (CV), in both alkaline (pH 11), where the species is fairly stable, and physiological (pH 7.4) conditions, where it is unstable. To understand its generation with respect to the plasma chemistry, we varied the shielding gas composition of CAPs to directly impact on the RONS composition at the plasma-liquid interface. We observed that the production and accumulation of RONS in liquids, including O(2)(center dot-)depends on the plasma composition, with N-2-based shieldings providing the highest superoxide concentrations (few 10s of micromolar at most) and of its derivatives (hundreds of micromolar). In situ spectroscopic and electrochemical analyses provide a high resolution kinetic and quantitative understanding of the interactions between CAPs and physiological solutions for biomedical applications.

Abstract: Electron-withdrawing perfluoroalkyl peripheral groups grafted on phthalocyanine (Pc) macrocycles improve their single-site isolation, solubility, and resistance to self-oxidation, all beneficial features for catalytic applications. A high degree of fluorination also enhances the reducibility of Pcs and could alter their singlet oxygen (1O2) photoproduction. The ethanol/toluene 20:80 vol % solvent mixture was found to dissolve perfluorinated FnPcZn complexes, n = 16, 52, and 64, and minimize the aggregation of the sterically unencumbered F16PcZn. The 1O2 production ability of FnPcZn complexes was examined using 9,10-dimethylanthracene (DMA) and 2,2,6,6-tetramethylpiperidine (TEMP) in combination with UV–vis and electron paramagnetic resonance (EPR) spectroscopy, respectively. While the photoreduction of F52PcZn and F64PcZn in the presence of redox-active TEMP lowered 1O2 production, DMA was a suitable 1O2 trap for ranking the complexes. The solution reactivity was complemented by solid-state studies via the construction of photoelectrochemical sensors based on TiO2-supported FnPcZn, FnPcZn|TiO2. Phenol photo-oxidation by 1O2, followed by its electrochemical reduction, defines a redox cycle, the 1O2 production having been found to depend on the value of n and structural features of the supported complexes. Consistent with solution studies, F52PcZn was found to be the most efficient 1O2 generator. The insights on reactivity testing and structural–activity relationships obtained may be useful for designing efficient and robust sensors and for other 1O2-related applications of FnPcZn.

Abstract: There is an urgent need for sensing strategies to screen perfluoroalkyl substances (PFAS) in aqueous matrices. These strategies must be applicable in large-scale monitoring plans to face the ubiquitous use of PFAS, their wide global spread, and their fast evolution towards short-chain, branched molecules. To this aim, the changes in fluorinated self-assembled monolayers (SAM) with different architectures (pinholes/defects-free and with randomized pinholes/defects) were studied upon exposure to both long and short-chain PFAS. The applicability of fluorinated SAM in PFAS sensing was evaluated. Changes in the SAM structures were characterised combining electrochemical impedance spectroscopy and voltam-metric techniques. The experimental data interpretation was supported by molecular dynamics simu-lations to gain a more in-depth understanding of the interaction mechanisms involved. Pinhole/defect-free fluorinated SAM were found to be applicable to long-chain PFAS screening within switch-on sensing strategy, while a switch-off sensing strategy was reported for screening of both short/long-chain PFAS. These strategies confirmed the possibility to play on fluorophilic interactions when designing PFAS screening methods.(c) 2022 Elsevier B.V. All rights reserved.

Abstract: Enhancing aluminium interaction with graphene-based materials is of crucial importance for the development of Al-storage materials and novel functional materials via atomically precise doping. Here, DFT calculations are employed to investigate Al interactions with non-doped and N-doped graphene nanoribbons (GNRs) and address the impact of the edge sites and N-containing defects on the material's reactivity towards Al. The presence of edges does not influence the energetics of Al adsorption significantly (compared to pristine graphene sheet). On the other hand, N-doping of graphene nanoribbons is found to affect the adsorption energy of Al to an extent that strongly depends on the type of N-containing defect. The introduction of edge-NO group and doping with in -plane pyridinic N result in Al adsorption nearly twice as strong as on pristine graphene. Moreover, double n-type doping via N and Al significantly alters the electronic structure of Al,N-containing GNRs. Our results suggest that selectively doped GNRs with pyridinic N can have enhanced Al-storage capacity and could be potentially used for selective Al electrosorption and removal. On the other hand, Al,N-containing GNRs with pyridinic N could also be used in resistive sensors for mechanical deformation. Namely, strain along the longitudinal axis of these dual doped GNRs does not affect the binding of Al but tunes the bandgap and causes more than 700-fold change in the conductivity. Thus, careful defect engineering and selective doping of GNRs with N (and Al) could lead to novel multifunctional materials with exceptional properties. [GRAPHICS]

Abstract: The smuggling of illicit drugs urges the development of new tools for rapid on-site identification in cargos. Current methods rely on presumptive color tests and portable spectroscopic techniques. However, these methods sometimes exhibit inaccurate results due to commonly used cutting agents, the colorful nature of the sample or because the drugs are smuggled in common goods. Interestingly, electrochemical sensors can deal with these specific problems. Herein, an electrochemical device is presented that uses affordable screen-printed electrodes for the electrochemical profiling of several illicit drugs by square-wave voltammetry (SWV). The identification of the illicit compound is based on the oxidation potential of the analyte. Hence, a library of electrochemical profiles is built upon the analysis of illicit drugs and common cutting agents. This library allows the design of a tailor-made script that enables the identification of each drug through a user-friendly interface (laptop or mobile phone). Importantly, the electrochemical test is compared by analyzing 48 confiscated samples with other portable devices based on Raman and FTIR spectroscopy as well as a laboratory standard method (i.e., gas chromatography-mass spectrometry). Overall, the electrochemical results, obtained through the analysis of different samples from confiscated cargos at an end-user site, present a promising alternative to current methods, offering low-cost and rapid testing in the field.