Aqueous NH Research Articles

Layered V10O24·nH2O as a new ammonium ion host material for aqueous and quasi-solid-state ammonium-ion hybrid capacitors

Aqueous ammonium-ion hybrid capacitors (AIHCs) emerge as a promising candidate for efficient and sustainable charge storage. Yet, a pivotal challenge lies in the development of an ammonium ion (NH4+) host material that possesses high capacity and prolonged cycle life. Herein, we explore the potential of layered V10O24·nH2O, synthesized via electrodeposition method, for use in high-capacity aqueous NH4+ storage. Our investigation, supported by both experimental observations and first-principles theoretical computations, has demonstrated that the layered V10O24·nH2O exhibits commendable electrochemical performance for aqueous NH4+ storage, which is attributed to the presence of certain amount of crystal water and unique nanowire network structure. This allows for a high specific capacity of 203.1 mAh g−1 at 0.3 A g−1, and the capacity retention is 97.6 % after 20,000 cycles. Ex-situ characterizations uncovered that the insertion and extraction of NH4+ in the V10O24·nH2O layers are reversible processes, accompanied by changes in the oxidation states of vanadium and the reversible contraction and expansion of the interlayer spacing. Furthermore, the as-assembled AIHCs device not only exhibits a voltage window of 1.8 V, surpassing other types of hybrid capacitors, but also retains 82.8 % capacitance after 10,000 cycles, showcasing its good flexibility and potential for series–parallel combinations. The study highlights the potential of layered V10O24·nH2O electrodes for sustainable energy storage applications and offers some insights for high-performance hybrid capacitors with non-metallic NH4+ as the charge carrier.

Nano-Structured CuO Grown with Aqueous NH3 for Salivary Glucose Detection

CuO nanostructures grown on flexible Cu foil by a simple chemical bath deposition in a solution of aqueous ammonia have been explored for non-invasive and nonenzymatic detection of salivary glucose. The nanostructured electrode developed with 100 μl of aqueous ammonia achieves a high sensitivity of 3243 μA mM−1 cm−2, linear range up to 3 mM, and limit of detection of 0.77 μM. The electrode also demonstrates good anti-interference properties, high reproducibility, repeatability, and long-term stability up to 30 days. In addition, the electrode exhibits remarkable sensitivity of 2865 μA mM−1 cm−2 for salivary glucose detection. To explore its potential for non-invasive detection of actual salivary glucose, pre-prandial and post-prandial salivary glucose of different human volunteers were measured using the electrode and were found to be correlated with corresponding blood glucose levels. Development and investigation of similar sensors for non-invasive detection via untraditional methods would certainly pave the way towards next generation glucose monitoring devices and systems.

Synergistically constructed lamination-like network of redox-active polyimide and MXene via π-π interactions for aqueous [formula omitted] storage

As a nonmetallic charge carrier, ammonium ion (NH4+) has garnered significant attention in the construction of aqueous batteries due to its advantages of low molar mass, small hydration size and rapid diffusion in aqueous solutions. Polymers are a kind of potential electro-active materials for aqueous NH4+ storage. However, traditional polymer electrodes are typically created by covering the bulky collectors with excessive additives, which could lead to low volume capacity and unsatisfactory stability. Herein, a nanoparticle-like polyimide (PI) was synthesized and then combined with MXene nanosheets to synergistically construct an additive-free and self-standing PI@MXene composite electrode. Significantly, the redox-active PI nanoparticles are enclosed between conductive MXene flakes to create a 3D lamination-like network that promotes electron transmission, while the π-π interactions existing between PI and MXene contribute to the enhanced structural integrity and stability within the composite electrode. As such, it delivers superior aqueous NH4+ storage behaviors in terms of a notable specific capacity of 110.7 mA·h·cm–3 and a long lifespan with only 0.0064% drop each cycle. Furthermore, in-situ Raman and UV–Vis examinations provide evidence of reversible and stable redox mechanism of the PI@MXene composite electrode during NH4+ uptake/removal, highlighting its significance in the area of electrochemical energy storage.

Online headspace monitoring of volatile organic compounds using proton transfer reaction-mass spectrometry: Application to the multiphase atmospheric fate of 2,4-hexadienedial

Chemical processes in clouds have been suggested to contribute significantly to the mass of organic aerosol particles in the atmosphere. Experimental and theoretical evidence suggest that organic mass production in clouds can be substantial and depends on the concentration of organic precursor compounds available in the gas phase. The present study aims at studying the aqueous phase reactivity of one of these overlooked precursors, i.e. 2,4-hexadienedial, an important and toxic intermediate in the atmospheric oxidation of aromatic species. Cautious synthesis and purification of 2,4-hexadienedial was performed. Its effective Henry's law constant was measured using a new simple and fast method based on online flow-injection analysis. The reactivity of 2,4-hexadienedial in the aqueous phase relevant to atmospheric conditions was studied, including hydrate formation, photolysis, ∙OH- and SO4∙--oxidation as well as reaction with NH3. The results revealed a low hydration constant compared to other dicarbonyls (Khyd1 = 7 × 10−2) and no dihydrate formation, indicating in an intermediate solubility (KH = 1.0 × 104 M atm−1) and high absorption cross sections (σ278nm > 10−16 cm2 molecule−1). Compared to its gas phase photolysis, its aqueous phase photolysis showed low quantum yields (Φ290–380nm = 0.9 %), and a significant red shift of the absorbance maximum, leading to a fast aqueous photolysis kinetics (Jaq,atm = 8.7 × 10−5 s−1) under atmospheric solar radiation, but no triplet state formation was detected. Radical oxidation experiments revealed extremely rapid oxidation kinetics (k∙OH = 1.10 × 1010 M−1 s−1 and kSO4∙- = 1.4 × 109 M−1 s−1) driven by fast addition of the radicals to the unsaturated bonds. In contrast, the reaction with aqueous NH3 (kNH3 = 2.6 × 10−3 M−1 s−1) was found slower than glyoxal and 2-butenedial, likely due to the hyperconjugation of 2,4-hexadienedial. Using these new data complemented with assumed aqueous phase kinetics (for NO3, 3C* and 1O2 reactions) and previous gas-phase kinetic ones, the multiphase atmospheric fate of 2,4-hexadienedial was established under atmospheric conditions reported from previous field measurements and models. The results revealed a short day lifetime (∼1 h) and a long night lifetime (>12 h). It was shown that daytime atmospheric chemistry of 2,4-hexadienedial can be influenced by aqueous-phase reactivity during cloud events, up to ∼50 % under thick cloud conditions (Liquid Water Content >2000 g/m3), indicating that even a compound of intermediate solubility can be strongly affected by condensed-phase reactivity. Besides its fast aqueous phase reactivity towards ∙OH and photolysis, its daytime condensed-phase reactivity may be driven by reactions with dissolved triplet states (3C*), up to 35 %, highlighting the need to study further the kinetics, the nature and concentrations of dissolved 3C* under various atmospheric conditions. In addition, the molecular properties and atmospheric behavior of 2,4-hexadienedial were found different from those of glyoxal and 2-butenedial, highlighting the need for detailed atmospheric reactivity studies of polyfunctional compounds, in particular unsaturated compounds.

Porous carbon-MnO2 heterostructures for high energy density aqueous ammonium-ion asymmetric supercapacitors

Aqueous ammonium-ion (NH4+) is gaining attention as a viable energy storage option due to the use of NH4+ as the charge carrier, offering advantages of resource abundance, safety, fast diffusion, and a unique storage mechanism. Despite these benefits, the development of storage devices with NH4+ as the charge carrier are still in the early stages, highlighting the crucial need to explore suitable electrode materials for the production of high-performance devices. In this study, broken porous carbon nanocages (BPCs) serve as the support structure to form a heterostructure with δ-MnO2 nanosheets (MnO2-BPCs) grown onto them, building aqueous NH4+ asymmetric supercapacitors (ASCs). Both MnO2-BPCs and BPCs act as host materials for storing aqueous NH4+, exhibiting high specific capacitance and long cycling durability. The assembled NH4+ ASCs present good capacitive performance, with a large specific capacitance of 223 F g−1 and capacitance preservation of 91.4 % over 10,000 cycles. The high energy density achieved by NH4+ ASCs is crucial for advanced energy storage thanks to their elevated specific capacitance and broad operating voltage. The balanced capacitive performance of the positive and negative electrodes is essential in enhancing the energy storage capabilities of NH4+ ASCs. This work provides a straightforward method for creating porous carbon-MnO2 heterostructures for NH4+ storage and paves the way for designing aqueous NH4+-based sustainable energy storage systems (SESSs) for capacitive energy storage.

Modulating NH4+ in vanadium oxide framework for high-efficient aqueous NH4+ storage

Aqueous energy storage systems have garnered significant attention due to their inherent advantages, including low cost, high eco-sustainability, and enhanced safety profiles. Nonmetal ion as a charge carrier is a fascinated paradigm shift just recently. Vanadium-based materials for ammonium ion (NH4+) storage have received considerable interest and have been demonstrated to serve as highly efficient NH4+ (de)intercalation host materials. However, tuning their structure for enhanced NH4+ storage presents significant challenges. Herein, we report a strategy for the pre-intercalation of NH4+ in vanadium oxide framework to study on the influence of the amount of ammonium ions on their NH4+ storage properties. The results from the experiments and density functional theory (DFT) calculations demonstrate that the appropriate quantity of pre-inserted ammonium ions boosts the (de)intercalation of NH4+ and exhibits the superior electrochemical properties. Moreover, excessive pre-inserted ammonium ions in vanadium oxide framework occupy the active sites for storing NH4+, whereas insufficient pre-inserted ammonium ions in vanadium oxide framework do not support the interlayer space enough for rapid (de)intercalation of NH4+. All results elucidate that modulating NH4+ in vanadium oxide framework enables highly efficient aqueous ammonium ion storage for supercapacitors (SCs). At 0.5 A·g−1, the specific capacitance of 341F·g−1 (171 mAh·g−1) and stable cycle performance of nearly 100 % after 10,000 cycles are achieved. The assembled hybrid supercapacitor exhibits the capacitance with 330 mF·cm−2 at 1 mA·cm−2, and energy density with 13.7 Wh·kg−1 at 22.1 W·kg−1, complemented by commendable mechanical durability and energy output characteristics. The profound insights gleaned from this study illuminate the strategic modulation of NH4+ ions, unveiling the vast potential of vanadium-based materials for efficient NH4+ storage applications.

The spatiotemporal heterogeneity of fertosphere hotspots impacted by biochar addition and the implications for NH3 and N2O emissions

The fertosphere, as the interfaces between fertilizer granular and soil particles, represents a key hotspot for nitrogen transformation processes, particularly for ammonia (NH3) and nitrous oxide (N2O) emissions. Understanding the heterogeneity of the fertosphere, especially when incorporating organic amendments like biochars, is crucial for predicting NH3 and N2O emissions after soil fertilization. In this study, we investigated the effects of three types of biochar (pristine, aged, and acid-washed biochar) on heterogeneity of fertosphere induced by localized urea application. pH-specific planar optodes were employed to visualize pH gradients in fertosphere hotspots with high spatial and temporal resolution. In addition, we conducted thorough measurements of the gradient distribution of electric conductivity (EC), mineral N, aqueous NH3 in soil and enzyme activities relevant to nitrification. Concurrently, NH3 and N2O emissions from the soil were continuously monitored at a high temporal resolution. Initially, urea-induced fertosphere exhibited significant NH3 emissions, primarily attributed to the pH elevation resulting from urea hydrolysis. However, after 6 days, NH3 emissions subsided, and there was a notable sharp increase in N2O emissions. Importantly, compared to urea application alone, the inclusion of pristine biochar led to a delay in soil pH decline with a 19% rise in NH3 emission. Aged biochar, characterized by a higher content of oxygen functional groups, demonstrated increased NH4+/NH3 adsorption capacity and enhanced ammonia monooxygenase (AMO) activity in soil, resulting in an 18% reduction in NH3 emission. While a slight decrease of 5% in NH3 cumulative emission was observed in the acid-washed biochar treatment. Notably, biochar could potentially promote nitrification-derived N2O emissions due to the accumulation of NH3 oxidation products (NH2OH). These findings could contribute to refining N transformation models for fertilized soils, and optimizing N fertilizer application strategies.

Analogous Confinement Effect Enables High Stability and High Capacity Ammonium Storage in Polyaniline@Poly(o-fluoroaniline)@Carbon Layer.

Rechargeable aqueous ammonium ion (NH4 +) batteries have attracted much attention due to the unique properties of NH4 +. Polyaniline (PA) with outstanding conductivity is a potential cathode material, but it can be oxidized to pernigraniline (PG) rapidly, resulting in its poor stability. In this study, polyaniline@poly(o-fluoroaniline)@carbon layer (PA@POFA@C) is prepared for excellent and durable NH4 + storage. PA@POFA@C exhibits a high capacity of 208 mAh g-1 at 0.2 A g-1 and maintains 126 mAh g-1 at 10 A g-1. More importantly, an excellent capacity retention rate of 88.24% is achieved after 2000 cycles with ≈100% coulombic efficiency. Spectroscopy studies suggest analogous confinement effect can effectively limit the escape of hydrogen in imine group, and form the hydrogen-restricted region between the PA and POFA layer which can provide H+ for the complete reduction of PG. Meanwhile, the hydrophobic effect of POFA effectively restrains the hydrolysis of PG. Interestingly, the introduction of C layer improves the hydrophilicity of electrode and shortens the activation process, serving as the outermost protective layer of the electrode. Finally, PA@POFA@C achieves desirable electrochemical performances with analogous confinement effect. This research provides ideas for the preparation of advanced polymer electrodes for aqueous NH4 + batteries.

Synthesis of conducting polymer intercalated sodium vanadate nanofiber composites as active materials for aqueous zinc-ion batteries and NH3 gas sensors at room temperature

Among the key technologies required for building industrial safety systems is portable integrated safety devices based on gas sensors and rechargeable batteries. In preparation for such integrated devices, this study focuses on the synthesis of sodium vanadate nanofibers (SVNF) and poly(3,4-ethylene dioxythiophene) (PEDOT) intercalated SVNF (E-SVNF) composites by a simple sonochemical approach for room temperature NH3 gas sensing and zinc ion battery (ZIB) studies. Applying E-SVNF to ZIBs resulted in superior rate capability, with a capacity of 192.13 mAh g−1 at 15 A g−1. Furthermore, they demonstrated long-term cycling stability, maintaining 83.47% of their capacity at 15 A g−1 even after 3,000 cycles. The gas sensor incorporating E-SVNF showcased a high response and excellent selectivity, even at room temperature, with response values of 1.059 for 10 ppm and 1.113 for 70 ppm of NH3 gas. These remarkable enhancements in the electrochemical performance of ZIBs and the gas sensor are attributed to the insertion of conductive polymers between SVNF layers. This resulted in improved electrical conductivity, increased interlayer distance in the vanadate nanofiber structure, enhanced layered structural stability, increased oxygen vacancies, a decreased work function, and the formation of p-p heterojunctions, all of which contribute to improved functionality of the composites materials. This research is expected to serve as a cornerstone for the development of industrial safety systems.

A new model-aided approach for the design of packed columns for CO2 absorption in aqueous NH3 solutions

A novel model-based approach to design packed beds for CO2 absorption with NH3 is proposed and experimentally validated. The two-film theory is adopted to model gas/liquid mass transfer while the thermodynamic equilibrium among ion species is considered in the liquid. Such strategy allows to simulate both CO2 absorption and NH3 evaporation, that represent the most important aspects to improve capture efficiency and process cost-effectiveness. The resulting ODEs system is a two boundary-value problem which is solved by means of the shooting method. The model is then exploited to develop a new algorithm that, based on the adopted operating conditions, evaluates the packed bed height as a function of the desired capture efficiency. The height calculated for different combinations of operating conditions is successfully compared with the real height of the experimental column, thus confirming the reliability of the developed tool which can be run with very low computational loads.

Tannic acid crosslinked chitosan-guar gum composite films for packaging application

Chitosan (CH)-guar gum (GG) composite films crosslinked with tannic acid (TnA) were prepared by solution casting method. The films were then immersed in 5 % aqueous NH3 and dried again. They were characterized by IR spectroscopy, wide angle x-ray diffraction and thermogravimetric analysis. All the films were studied for physicochemical properties such as moisture content, swelling, solubility in water, water contact angle, water vapor permeability, opacity, tensile strength and antioxidant activity. The physicochemical and mechanical properties of films changed significantly when compared to CH as reflected by an increase in the amorphous domains of the films, a decrease in moisture content, swelling and solubility in water. The films turned hydrophobic with concomitant decrease in moisture content, swelling, water-solubility and exhibited improved UV absorption as well as mechanical strength, which in turn was dependent on the tannic acid concentration. These results along with enhanced antioxidant properties, UV absorption with no significant change in water vapor permeation compared to CH suggested that the films could find application in packaging applications.

Technoeconomic evaluation of post-combustion carbon capture technologies on-board a medium range tanker

The international maritime organization has recently set targets and timelines for reducing global greenhouse gas emissions from the maritime industry, which currently stand at 1.1 Gt/year and make 3 % of the global emissions. Reducing emissions by increasing engine efficacy is the immediate target, but there is a limit to how much this path can achieve. Onboard post-combustion carbon capture and concentration in large marine vessels is emerging as an interim approach to reduce maritime emissions until large-scale deployment of low/zero emission fuels become viable. In this paper, we evaluate three carbon capture technologies (chemical absorption using either aqueous MEA or aqueous NH3 as the solvent, cryogenic separation, and membrane separation) for a medium-range tanker for two fuels, namely heavy fuel oil and liquefied natural gas. The capture cost per tonne of CO2 (recovery>90 %, purity>95 %) was considered as the assessment criterion, with simultaneous evaluation of other aspects such as energy and space demands. The simulations were carried out using MATLAB and ASPEN V12. For rate-based models, the adjustable parameters for the model were tuned using pilot plant data. Additionally, options for hot and cold energy integration were also assessed and implemented. Based on the reference ship conditions and assessment criteria, the simulation studies show that amine-based absorption is the best prospect for on-board capture by a clear margin.

Band engineering in Ti2N/Ti3C2Tx-MXene interface to enhance the performance of aqueous NH4+-ion hybrid supercapacitors

The aqueous hybrid supercapacitor (AHSC) based on ammonium ion (NH4+) is an interesting energy storage device with excellent properties. However, the scarcity of appropriate and effective cathode materials limited its practicality. Two-dimensional (2D) transition metal nitrides, carbides, or carbonitrides (MXenes) show potential as cathode materials, but their low capacitance limits their applicability. Here, we synthesized N-functionalized 2D MXene (Ti3C2Tx) with Ti2N interface engineering (Ti2N/Ti3C2Tx), which displayed not only superior capacitance and rate capability but also a cycling stability than pristine Ti3C2Tx. Ex-situ XRD and XPS were used to study the charge storage mechanism at the interface of Ti2N/Ti3C2Tx. Furthermore, density functional theory (DFT) calculations were employed to validate the superior conductivity at the interface of the Ti2N/Ti3C2Tx (Tx = OH) electrode. Moreover, AHSC was assembled with the Ti2N/Ti3C2Tx as cathode, and activated carbon as anode possesses outstanding energy storage performance. This study not only elucidates the charge storage process of Ti2N/Ti3C2Tx but also provides new insights for designing novel cathode materials for energy storage devices.

Kinetic and thermodynamic analysis of ammonia electro-oxidation over alumina supported copper oxide (CuO/Al2O3) catalysts for direct ammonia fuel cells

In this work, ammonia electrooxidation (AEO) is studied to probe the electrochemical behavior of aqueous NH3 as direct fuel by implication of gamma alumina supported copper oxide catalysts (CuO/Al2O3). Precipitation and impregnation techniques are adapted to synthesize the substrate Al2O3, and loading of different ratios (1%, 2%, 3%, 4%) of active precursor i.e., CuO, respectively. Small average crystallite sizes (DAvg) in range of 1.46–6.76 nm and smaller particle sizes from micrographs proposed a superb activity of the catalysts. Modified GCE exhibited the excellent conductive properties towards standard redox probe K4[Fe(CN)6] and KCl, displaying a high active electrochemical surface area of up to 0.0021 cm2. Current profiles in response to increase in scan rates, concentrations of ammonia and temperature have been observed in 0.1 M KOH, thereby estimating the thermodynamic and kinetic constraints of the AEO process. Attributed to the electroactive properties towards AEO, CuO/Al2O3 is found to exhibit the desirable physiochemical properties owing to large oxidation current, large diffusion coefficient “D°” (3.6 × 10-9 cm2 s-1), large rate constant “ko” (1.2 × 10-5 cm s-1), large system entropy “ΔS” (-108 J K-1 mol-1), high change in enthalpy “ΔH” (72.3 J mol-1) and low activation energy “ΔG” (32.8 kJ mol-1). Resultingly, the oxidation of ammonia is found to be facile and robust by incorporation of CuO/Al2O3 catalysts owing to large ko, ΔH and ΔH. This study opened a gateway towards eco-benign and economical efficient energy generation and viable market entry of direct ammonia fuel cells.

Biomonitoring of dairy farm emitted ammonia in surface waters using phytoplankton and periphyton

The increasing environmental abundance of reactive N (‘Nr’) entails many adverse effects for society such as soil degradation and eutrophication. In addressing the global surplus of N, there is a pressing need to quantify local sources and dynamics of Nr. Although quantified as an important anthropogenic source of Nr, the spatiotemporal patterns of ammonia (‘NH3’) emitted by dairy farming and its resulting pressure on local surface waters lacks quantification. Quantification could optimize farm management with minimized losses of valuable nitrogen and protection of freshwater ecology. This study aimed to unravel spatiotemporal dynamics of ammonia nitrogen emitted by a dairy farm in the atmospheric and aquatic geo-ecosphere. Atmospheric NH3 and aqueous ammonium (‘NH4+’) were determined over time, together with meteorological variables. Aquatic biomonitors (periphyton and phytoplankton) were employed to monitor the spatial impacts of cattle-stable emitted NH3. Atmospheric NH3 on the farm was significantly regulated by wind, sharply declining over increasing distances from the stable (average decrease in the dominant wind direction from 55.5 μg/m3 at 20 m to 5.8 μg/m3 at 500 m, in the other wind directions values decreased from 38.3 μg/m3 to 6.0 μg/m3). This was also reflected in local surface water concentrations of NH4+, with average concentrations decreasing from 37.0 mg [NH4+-N]/L at 65 m to 4.8 mg [NH4+-N]/L in the dominant wind direction, and from 1.2 to 0.7 in other directions. Periphyton biomass, total N (“TN”) and δ15N all significantly reflected spatiotemporal dynamics of atmospheric NH3 and aqueous NH4+, as did phytoplankton TN. The cattle stable significantly influenced local water quality through atmospheric spreading of NH3, and both aquatic biomonitors were influenced by and reflected dairy farm emitted NH3 with a sharp dilution over distance. This study strongly underlines the importance of atmospheric transport of dairy farm emitted NH3 and its effects on local water quality.

Environmental effects on ammonium adsorption onto clay minerals: Experimental constraints and applications

Adsorption of ammonium (NH4+) by clay minerals in soil/sediment and altered oceanic crust plays an important role in Earth's geological nitrogen cycle by transporting nitrogen from the biosphere and hydrosphere into the lithosphere. Clay minerals have also been proposed to play an important role in catalyzing abiotic synthesis of organic compounds (which also requires adsorption enrichment of NH4+) for the origin of life. Consequently, nitrogen in clay minerals could be used as a potential tracer for reconstructing paleo-environments and searching for life on extraterrestrial planets and moons. However, the premise of these applications, i.e., how different environmental conditions (e.g., ambient pH, temperature, salinity and aqueous NH4+ concentration) would affect NH4+ adsorption onto clay minerals, is still poorly understood. In this study, we carried out laboratory experiments to examine the NH4+ adsorption behavior of several clay minerals (montmorillonite, vermiculite, illite, chlorite, kaolinite) under conditions varying in aqueous NH4+ concentration (20, 50, 100, 200, 500, 1000 mg/L), pH (2, 5, 7), salinity (fresh water vs. artificial seawater), and temperature (23, 50, 70 °C). Our results show that the NH4+ adsorption on all studied minerals is very fast (reaching equilibrium within a few minutes). The NH4+ adsorption capacity is however strongly mineral-dependent and follows the order of vermiculite ≈ montmorillonite ≫ illite > kaolinite ≈ chlorite. The much higher NH4+ adsorption capacities of vermiculite and montmorillonite can be attributed to the NH4+ adsorption in their interlayer sites in addition to the surface and edge sites that dominate the NH4+ adsorption in illite, kaolinite, and chlorite. But illite contains some frayed edge sites that are accessible to NH4+ adsorption, and thus has higher adsorption capacity than kaolinite and chlorite. The NH4+ adsorption on all these clay minerals is highly susceptible to environmental conditions (e.g., aqueous NH4+ concentration, pH, temperature, and salinity). For example, the NH4+ adsorption capacities of montmorillonite and vermiculite significantly decrease following the increase in salinity and the decreases in pH and aqueous NH4+ concentration. Our experimental data can be best fitted by the Freundlich Model, which suggests that NH4+ adsorption on clay minerals likely occurs in energetically heterogeneous surface sites. Based on these results, we provide new insights into the understanding of NH4+ migration from seawater to sediments and altered oceanic crust, preservation capability of the paleoenvironmental nitrogen signature in clay minerals, and optimal conditions for clay to catalyze organic synthesis toward the origin of life on the early Earth.

Critical Advances of Aqueous Rechargeable Ammonium Ion Batteries

Aqueous rechargeable batteries have drawn wide attention owing to the advantages of low cost, high safety, and rapid kinetic process. In recent years, the use of NH4+ ions and other nonmetallic ions as carrier batteries has come into researchers’ view. The storage of NH4+ shows fast diffusion kinetics and the ability to achieve highly reversible redox processes by forming hydrogen bonds between NH4+ and electrode materials. Designing and exploration of advanced materials for NH4+ storage are of high significance in building high‐performance aqueous battery systems. This review summarizes the latest advances of critical materials, including Prussian blue analogs, transition metal oxides, and organic compounds for NH4+ batteries. Comparison of properties among different materials is discussed in detail. Different NH4+ storage behaviors according to several kinds of materials are demonstrated. Finally, the challenges and valuable perspectives for the further development of aqueous NH4+ batteries are also provided.

Synthesis of Polystyrene@TiO2 Core–Shell Particles and Their Photocatalytic Activity for the Decomposition of Methylene Blue

In this study, we investigated the preparation conditions of polystyrene (PS)@TiO2 core–shell particles and their photocatalytic activity during the decomposition of methylene blue (MB). TiO2 shells were formed on the surfaces of PS particles using the sol–gel method. Homogeneous PS@TiO2 core–shell particles were obtained using an aqueous NH3 solution as the promoter of the sol–gel reaction and stirred at room temperature. This investigation revealed that the temperature and amount of the sol–gel reaction promoter influenced the morphology of the PS@TiO2 core–shell particles. The TiO2 shell thickness of the PS@TiO2 core–shell particles was approximately 5 nm, as observed using transmission electron microscopy. Additionally, Ti elements were detected on the surfaces of the PS@TiO2 core–shell particles using energy-dispersive X-ray spectroscopy analysis. The PS@TiO2 core–shell particles were used in MB decomposition to evaluate their photocatalytic activities. For comparison, we utilized commercial P25 and TiO2 particles prepared using the sol–gel method. The results showed that the PS@TiO2 core–shell particles exhibited higher activity than that of the compared samples.

Detection and confirmation of fentanyls in high clay-content soil by electron ionization gas chromatography-mass spectrometry.

Detection of illicit drugs in the environment, particularly in soils, often suggests the present or past location of a clandestine production center for these substances. Thus, development of efficient methods for the analysis and detection of these chemicals is of paramount importance in the field of chemical forensics. In this work, a method involving the extraction and retrospective confirmation of fentanyl, acetylfentanyl, thiofentanyl, and acetylthiofentanyl using trichloroethoxycarbonylation chemistry in a high clay-content soil is presented. The soil was spiked separately with each fentanyl at two concentrations (1 and 10 μg/g) and their extraction accomplished using ethyl acetate and aqueous NH4 OH (pH ~ 11.4) with extraction recoveries ranging from ~56% to 82% for the high-concentration (10 μg/g) samples while ranging from ~68% to 83% for the low-concentration (1 μg/g) samples. After their extraction, residues containing each fentanyl were reacted with 2,2,2-trichloroethoxycarbonyl chloride (Troc-Cl) to generate two unique and predictable products from each opioid that can be used to retrospectively confirm their presence and identity using EI-GC-MS. The method's limit of detection (MDL/LOD) for Troc-norfentanyl and Troc-noracetylfentanyl were estimated to be 29.4 and 31.8 ng/mL in the organic extracts. In addition, the method's limit of quantitation for Troc-norfentanyl and Troc-noracetylfentanyl were determined to be 88.2 and 95.5 ng/mL, respectively. Collectively, the results presented herein strengthen the use of chloroformate chemistry as an additional chemical tool to confirm the presence of these highly toxic and lethal substances in the environment.

Boosting the energy storage performance of aqueous NH4+ symmetric supercapacitor based on the nanostructured molybdenum disulfide nanosheets

Nanostructured molybdenum disulfide (MoS2-2H phase) is a well-known metal dichalcogenide and promising material for electrochemical energy storage due to its unique properties, including structural stability, tuneable bandgap, and dangling-bond free basal surface. However, electrochemical devices based on MoS2 suffer from a short lifespan, low power density, and safety. Herein, we proposed 2H-MoS2 nanosheets as a capacitive energy storage material for aqueous ammonium-ion supercapacitors (AASCs) to address the above-mentioned issues. MoS2 nanosheets were grown on carbon cloth (MoS2@CC) with a wet-chemical method as binder-free capacitive electrodes, and a symmetric supercapacitor (SSC) was assembled to evaluate its energy storage performance. According to our simulation results with density functional theory (DFT), the ammonium sulfate (NH4)2SO4 aqueous solution was selected as the ammonium-ion electrolyte. The MoS2@CC electrode exhibits outstanding NH4+ ion storage by achieving a high capacitance of 1,010 Fg−1 at 1 Ag−1 and ultra-high rate performance (60% at 50-folded high current density) with 98% capacitance retention after 10,000 cycles. The pseudocapacitive charge storage process governs the NH4+ intercalation/deintercalation mechanism through the bounding/breaking of H with S atoms. A symmetric AASC was fabricated using the MoS2@CC and an aqueous (NH4)2SO4 electrolyte to assess the practical performance. The assembled AASC can operate at a wide potential window (0.0–1.5 V) and demonstrates high charge storage performance (237 Fg−1 at 1 Ag−1 and 133 Fg−1 at 50 Ag−1) with extremely stable rate and cycling performance of ∼ 99% up to 50,000 cycles. This study would give an effective and a succinct technique for creating metal dichalcogenide with porous structure for advanced NH4+ storage.