Adsorption Of NO Research Articles

Spatial-confined effect of CuOx microneedles bundles on TiO2 nanotubes: Reinforcing the adsorption and enrichment of ultralow concentration nitrate for efficient NH3 electrosynthesis

Nitrate (NO3−) Electroreduction to produce NH3 offers an alternative approach to sustainable production of NH3. Yet it remains challenging to simultaneously improve the adsorption and enrichment of low-concentration NO3−. Here, bundles of CuOx microneedles on TiO2 nanotubes (NTs) were developed by a spatial-confined electrodeposition strategy, achieving 87.7 % or 98.4 % NH3 FE at −0.25 V or −0.45 V vs RHE in 2 or 10 mM NO3− electrolytes, respectively. Both in-situ spectroscopy and finite element analysis simulation demonstrated that CuOx microneedle bundles and its interface between TiO2 NTs not only greatly improve the enrichment of low concentration NO3− and its derived-NO2− and the diffusion of NH3 product, but also enhance the adsorption of NO2− and H2O to facilitate the hydrodeoxygenation of NO3− as well as inhibit hydrogen evolution reaction competition. This work will provide a promising avenue to develop electrocatalysts to realize efficient catalytic conversion of reactants at low concentrations.

Facilitation of Pd–Ru Mixing in Nanoalloys of Immiscible Palladium and Ruthenium by NO Adsorption

Facilitation of Pd–Ru Mixing in Nanoalloys of Immiscible Palladium and Ruthenium by NO Adsorption

Promoting metal oxides–zeolite electron interaction on MnCeOx/HY catalyst for boosting nitrogen oxides reduction

The MnOx-CeO2 metal oxides are considered as promising alternative catalysts for selective catalytic reduction with NH3 (NH3-SCR) to remove NOx due to its excellent low temperature performance. However, their strong oxidative ability can lead to NH3 over-oxidation, narrowing the active temperature range and reducing N2 selectivity. Moreover, their weak surface acidity hampers medium to high-temperature activity and alkali metal resistance. Hence, in this study, MnCeOx metal oxides were coupled with HY zeolite to create MnCeOx/HY, demonstrating excellent NH3-SCR performance. The high dispersion of metal oxides on the zeolite surface and their close integration promoted strong electron interaction, effectively reducing oxygen vacancies and surface adsorbed oxygen concentrations. Consequently, the oxidative ability of active metal oxides was appropriately weakened, suppressing undesirable side reactions. MnCeOx/HY also notably suppressed NO adsorption and nitrate formation, promoting the catalytic reaction solely through the E-R mechanism and enhancing N2 selectivity. The abundant strong acid sites on the zeolite surface facilitates NH3 adsorption at moderate to high temperatures, notably expanding the active temperature window. Furthermore, the acid sites of HY zeolite serve as sacrificial sites, preferentially reacting with alkali metals, thus exhibiting excellent resistance to alkali metal poisoning on MnCeOx/HY. Combining with the DFT results, the structure-activity relationships in this study also reveal the importance of the effective synergy between acid sites and redox sites for optimal catalytic performance, offering valuable insights into the development of highly active and alkali-resistant denitrification catalysts.

The possibility of using the Zn (II) Butadiyne-linked porphyrin nanoring for detection and adsorption of AsH3, NO2, H2O, SO2, CS2, CO, and CO2 gases

The present research aims to study the probability of applying the Zn (II)-Butadiyne-linked porphyrin (ZBPN) nanoring for detection and adsorption of some of the most important air pollutants such as AsH3, NO2, H2O, SO2, CS2, CO, and CO2 gases by using the density functional theory (DFT) method. The key results of the thermodynamic calculations indicated that ZBPN nanoring is able to absorb SO2, AsH3, NO2, and H2O gases; while, it could not strongly adsorb CS2, CO, or CO2. Subsequent to the thermodynamic results, the changes of band gaps and the frontier molecular orbital (FMO) calculations show that ZBPN nanoring might release stronger signals in the presence of SO2 (σ = 1.64(1010) s), AsH3 (σ = 1.35(1010) s), and H2O (σ = 1.11(1010) s) single molecules compared to the other considered ones. Therefore, ZBPN could be used as a relatively good sensor for detection of SO2, AsH3, and H2O (compared to CS2, CO, CO2, and NO2 gases). Regarding the key findings of this research, it hopes that in the future, the results of the work be helpful for experimental synthesis of ZBPN nanoring for adsorption and sensing of the mentioned gases.

Layered sodium manganese oxides for toxic nitrogen dioxide gas removal in ambient conditions

In this study, Na0.7MnO2 samples were successfully synthesized using a solid-state synthesis route with Na and Mn acetate precursors. The resulting Na0.7MnO2 crystallized in a hexagonal lattice with space group P63/mmc. These materials were investigated for their capacity to adsorb 100 ppm of NO2 gas at room temperature. Na0.7MnO2 exhibited an exceptional NO2 adsorption capacity of 163.3 mg/g, surpassing many previously reported porous and non-porous materials. Comprehensive experimental and spectroscopic analyses confirmed the formation of NO, NO2–, and NO3– species, following NO2 adsorption on the Na0.7MnO2 surface. Theoretical calculations further supported the chemisorption of NO2 gas molecules on the Na0.7MnO2 surface, with a maximum adsorption energy of –1.937 eV. Spectroscopic and Bader charge analyses confirmed that the NO2 gas molecule acted as a charge acceptor species on the oxide surface. This work represents the first detailed study validating Na0.7MnO2 as an effective room-temperature adsorbent for capturing and mineralizing NO2 gas. The exceptional NO2 adsorption capacity and the mechanistic insights into the adsorption process suggest the promising potential of Na0.7MnO2 and related oxides for applications in NO2 gas capture and conversion.

Exploring effects of reactant’s chemical environments on adsorption and reaction mechanism by global optimization and IR spectrum calculation, using NO oxidation as a case

Reactant’s chemical environments derived from the type and concentration of surface species on heterogeneous catalysts do great effects on the structures of reactants and reaction pathway. Unraveling the arrangement of surface species and reaction mechanism at different reactant’s chemical environments in theory remains a substantial challenge due to the difficulty in obtaining the global stable configuration of surface species on catalysts and the lack of other theoretical evidences for the identification of surface species and reaction pathway. To solve this problem, a protocol combining the global optimization of surface species at different chemical environments with electronic structure analysis and IR spectrum calculation including frequency and intensity was proposed to unravel the arrangement of surface species and their reaction pathway in this work. Using NO adsorption and oxidation on Pt(111) and O-covered Pt(111) as a case, their stable structures were obtained by the global optimization; then the origins of the structural transformation of NO and NO2 at different environments were elucidated by electronic structure analysis; then the structures and reaction pathway were confirmed by comparing the experimental and calculated IR spectra of NO and NO2 with frequency and intensity. Utilizing this protocol, the stable structures of NO and its transformation, as well as oxidation pathway were revealed under varying chemical environments at the molecular level. It provides solid supports for identifying the stable arrangement of surface species, their transformation and reaction pathway, and can be easily extended to heterogeneous catalysis.

Hazardous CO, NO, NH3 gases over boron and beryllium doped α-CN monolayers: A first principles study for sensing and removal applications

The exploration of two-dimensional (2D) honeycomb layered structure (HLS) has garnered significant attention due to their multifunctional properties, with diverse applications emerging in various fields. Motivated by the challenges posed by hazardous gases such as CO, NO, NH3 and inspired by the unique properties of 2D HLS this first principles study digs into the structural, electronic, and sensing properties of Boron and Beryllium doped α-CN monolayers. Rendering the structural and electronic variations induced by B and Be doping, our analysis reveals distinct functionalities for α-CN monolayers. Boron doping at the C-site exhibits promise for NO and NH3 sensing (with 73 % and 77 % increment in adsorption energies), while B-doping at the N-site enhances suitability for gas removal applications. Similarly, Be doping demonstrates effectiveness in gas removal across both C and N sites. Notably, the ultra-fast response (2.31 × 10−8 s) observed for NO adsorption over B-doped α-CN highlights its potential as a rapid sensor. Additionally, work function analysis suggests the suitability of B-doped α-CN for φ-type sensing in NH3 adsorption. These findings underscore the applicability of doped α-CN monolayers in gas sensing mechanisms.

Interface Induced by Hydrothermal Aging Boosts the Low-Temperature Activity of Cu-SSZ-13 for Selective Catalytic Reduction of NOx.

Hitherto, sulfur poisoning and hydrothermal aging have still been the challenges faced in practical applications of the Cu-SSZ-13 catalyst for the selective catalytic reduction (SCR) of NOx from diesel engine exhaust. Here, we elaborately design and conduct an in-depth investigation of the synthetic effects of hydrothermal aging and SO2 poisoning on pristine Cu-SSZ-13 and Cu-SSZ-13@Ce0.75Zr0.25O2 core@shell structure catalysts (Cu@CZ). It has been discovered that Cu@CZ susceptible to 750 °C with 5 vol % H2O followed by 200 ppm SO2 with 5 vol % H2O (Cu@CZ-A-S) could still maintain nearly 100% NOx conversion across the significantly wider temperature region of 200-425 °C, which is remarkably broader than that of the Cu-SSZ-13-A-S (300-400 °C) counterpart. The experimental results show that the hydrothermal aging process results in the migration of highly active Cu species within the cage of Cu-SSZ-13 to the CZ surface, forming CuO/CZ with abundant interfaces, which significantly enhances the adsorption and subsequent activation of NO, leading to the generation of reactive N2O3 and HONO intermediates. Moreover, density functional theory (DFT) calculations reveal that the H of the HONO* species can function as Brønsted acid sites, effectively adsorbing NH3 to generate the active NH4NO2* intermediate, which readily decomposes into N2 and H2O. Furthermore, this pathway is the rate-determining step with an energy barrier of 0.93 eV, notably lower than that of the "standard SCR" pathway (1.42 eV). Therefore, the formation of the new CuO/CZ interface profoundly boosts the low-temperature NH3-SCR activity and improves the coresistance of the Cu@CZ catalyst to sulfur poisoning and hydrothermal aging.

DFT Study on the Janus ZrSSe Monolayer for Its Potential Application in NO Gas Sensing.

The growth of industry has resulted in increased global air pollution, necessitating the urgent development of highly sensitive gas detectors. In this work, the adsorption of the Janus ZrSSe monolayer for CO, CO2, NH3, NO, NO2, and O2 was studied by first-principles calculations. First, the stability of the ZrSSe monolayer is confirmed through calculations of cohesive energy and AIMD simulations. Furthermore, the calculations indicate that the Se layer exhibits higher selectivity and sensitivity toward gas molecules compared to the S layer. Specifically, among the gases adsorbed on the Se layer, NO has the shortest adsorption distance (1.804 Å), the lowest adsorption energy (-0.424 eV), and the greatest electron transfer (0.098 e). Additionally, density of states analysis reveals that adsorption of NO, NO2, and O2 on the Janus ZrSSe monolayer can induce a transition from a nonmagnetic to a magnetic state. The adsorption of NO not only alters the magnetic state but also induces a transition from a semiconductor to metal, which is highly advantageous for gas sensing applications. There results suggest that the Janus ZrSSe monolayer has the potential to serve as a highly sensitive detector for NO gas.

Enhancement of NO[formula omitted] sensing in Sb[formula omitted]Te[formula omitted]Se by vacancies

Topological insulators (TI) are a class of materials characterized by metallic edge states protected by time reversal symmetry from local perturbations such as defects while having a bulk insulating gap. Since the topological surface states are exposed to the environment, gas sensing applications could benefit from the higher carrier mobility of the topological surface states. In this work, we study the resistance response of Sb2Te2Se towards NO2 and the effects of vacancies introduced by annealing. We found that the vacancies greatly enhance the response and inferred the significant role the vacancies play in the mechanism of NO2 adsorption in Sb2Te2Se.

Investigating the Impact of Air Pollutants on Fuel Cell Performance and Durability: Experimental and Modeling Approaches

Fuel cells hold immense promise as efficient and sustainable power sources for transportation and stationary applications. However, their operation can be severely impacted by air pollutants, particularly sulfur dioxide (SO2) and nitrogen oxides (NOx). These pollutants can adsorb onto the platinum catalyst, leading to a decrease in fuel cell performance and durability.In this study, we investigate the impact of SO2 and NO2 on PEM fuel cell performance and durability. The contamination tests were carried out at a constant current density of 0.5 A.cm−2, and they consisted of four steps: a pre-poisoning step to evaluate initial performance (15-16 h), poisoning step (50 h), self-recovery in a pure air stream (20-21 h) and a driven CV-induced recovery. Electrochemical characterizations were carried out at the end of each step (Polarization curve, Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and H2 Crossover). Our initial investigation involved contaminating a single fuel cell with a low concentration of 0.1 ppm of sulfur dioxide (SO2). Remarkably, this resulted in a 1.1% decrease in cell voltage. Building on this foundation, our ongoing research aims to delve deeper into the impact of individual pollutant concentrations (SO2 and NO2) and their combined effects, considering varying temperatures and current densities to simulate real-world conditions.Simultaneously, a comprehensive model is being developed using Simscape in Matlab. The model accounts for the pollutants either as single-component gases or as a mixture. For single-component gas adsorption, the Langmuir Isotherm model is employed. To capture the competitive adsorption of SO2 and NO2 on platinum in gas mixtures, we are testing the Modified Competitive Langmuir Isotherm Model. The model will further be calibrated and validated using the experimental results.This combined experimental and modeling approach will provide a comprehensive understanding of the impact of air pollutants on fuel cell performance and durability. The insights gained from this study can inform the development of mitigation strategies and enhance the robustness of fuel cells in real-world applications as well as the sizing of a filter. Figure 1

Edge-enriched CeO2/MoS2 heterostructure with coupled interface for enabling selective room-temperature NO2 detection

Endowed with abundant oxygen vacancy and excellent redox properties, CeO2 has attracted extensive attention for potential application in gas sensing, while it suffers from high working temperature and low sensing response. Herein, the MoS2 nanoflowers with abundant edges are coupled with CeO2 nanoparticles and the edge-enriched heterostructure is formed at interface. Owing to the synergistic effects of strong adsorption, abundant adsorption sites, and coupled interface, the CeO2/MoS2 compounds behave excellent room-temperature NO2 sensing performance. The 5 ppm NO2-sensing response of compounds is enhanced by 1033 % and 450 % in company with pure CeO2 and MoS2, respectively and the low detection limit of 1 ppm, high recovery rate, excellent long-term stability and selectivity are also obtained at room temperature. According to first-principles calculation, the binding energy of CeO2 for NO2 is much more negative than that of MoS2. Functionalization of MoS2 with CeO2 substantially improves NO2 adsorption. The Fermi level of MoS2 is nearer to the vacuum level than that of CeO2. The electrons are transferred from MoS2 to CeO2 at interface to create an electric field and an electron accumulation layer is formed on CeO2 to promote electron exchange between NO2 and the sensor and the NO2-sensing response. The results promote the application of two-dimensional materials to gas sensing boding well for the wireless sensing systems development in environmental and safety monitoring.

Gas‐Sensing Properties of NO on Ce‐Doped Zinc Oxide: A DFT Study

AbstractOne of the most prevalent pollutants that pollute the environment is nitrogen oxide (NOx). NO and NO2 gases, which are hazardous to both human health and the environment, are included in NOx. The rare earth element Ce doped metal oxide semiconductor (MOS) ZnO is employed to reveal their NO gas sensing properties. Based on density functional theory (DFT) calculations, the optimized surface of ZnO (0001), Ce‐doped ZnO (0001), adsorbate structure of NO, and adsorbate NO on the modified ZnO (0001) surface are obtained. The gas sensing properties are examined through adsorption energy, Bader charge analysis, charge density difference (CDD), charge transfer, band structure, total density of state (DOS), and partial density of states (PDOS). For the Ce‐doped ZnO (0001) surface the NO adsorption energy is more negative than the bare ZnO. From the observation of Bader charge analysis, the charge transfer value increases from the substrate to adsorbate after doping with Ce, which indicates that the Ce‐doped ZnO (0001) surface is more favorable for NO gas sensing. Favorable electronic properties and suitable adsorption energy of Ce‐doped ZnO can be a potential gas sensor for NO molecule. The obtained DFT results are also compared with the existing experimental results.

Combined experimental and theoretical studies on adsorption characteristics of graphitic carbon nitride for flue gas molecules

Graphitic carbon nitride (g-C3N4) is a novel selective adsorbent for separation of Hg0 and Hg2+, which plays a pivotal role in mercury continuous emission monitoring systems (Hg-CEMS). However, some of the flue gas components may interfere with their binding characteristics with g-C3N4. This study employs the density functional theory (DFT) and experimental method to investigate the adsorption behavior of gas components on g-C3N4 and elucidates the intrinsic driving forces behind these interactions and assesses their impact on separation of Hg0 and HgCl2. The binding energies of H2O, SO2, CO2, NO, and O2 molecules on g-C3N4 are −0.575 eV, −0.530 eV, −0.309 eV, −0.246 eV, and −0.238 eV, respectively. The electronic structure and weak interaction analyses indicate that these interactions are primarily van der Waals forces caused by multi-atomic interactions. In contrast, the binding energy between HCl and g-C3N4 is −0.557 eV, primarily controlled by weak H-N covalent bonds. The co-adsorption results indicate that flue gas molecules exert negligible effects on the binding of HgCl2 to g-C3N4 because the changes in binding energy are within 0.15 eV. The experimental results verify that under practical operating conditions, the adsorption of H2O, HCl, SO2, CO2, NO, and O2 on g-C3N4 is below 0.1 %, demonstrating those components do not interfere with the separation of Hg0 and HgCl2 by g-C3N4, nor do they affect the regeneration performance of g-C3N4. This study provides new insights into the development and practical application of separation and conversion modules in Hg-CEMS technologies.

Phographene as a new carbon allotrope for adsorption and detection of SO2, AsH3, NO2, CF3H, and CO2 air pollutant gaseous species.

Phographene and its family member structures are of the newly proposed semiconductors for detection of chemicals. That is, in this project, the potential of using α-phographene (α-POG) both for adsorption and detection of five types of the most important air pollutant gases containing SO2, AsH3, CF3H, NO2, and CO2 species were investigated. The results of the time dependent density functional theory (TD-DFT) calculations indicate that during the adsorption of NO2, and SO2 by the sorbent, big redshifts occur (up to 866.2 nm, and 936.5, respectively) resulting in considerable changes in the orbitals and the electronic structures of the systems. Moreover, the results of the thermodynamic calculations reveal that α-POG could selectively adsorb SO2, NO2, and AsH3 gases (with different orders), but it could not adsorb the two other gases.Finally, the outcome of the band gap calculations shows that between all mentioned gases, α-POG could selectively detect the presence of SO2, and then NO2; while, this nanosheet could not sense the existence of AsH3, CF3H, or CO2 gases. All of the calculations were carried out by using the Gaussian 03 quantum chemical package. In addition, the physiochemical parameters were extracted from the output files for further calculations. Studies on all saddle points and the following calculations were performed applying the B3LYP/6-311g(d,p) level of theory.

NO2 Adsorption on Biochar Derived from Wood Shaving Litter: Understanding Surface Chemistry and Adsorption Mechanisms

NO2 Adsorption on Biochar Derived from Wood Shaving Litter: Understanding Surface Chemistry and Adsorption Mechanisms

Magnon Sensing of NO, NO2 and NH3 Gas Capture on CrSBr Monolayer.

Air pollution and greenhouse emissions are significant problems across various sectors, urging the need for advanced technologies to detect and capture harmful gases. In recent years, two-dimensional (2D) materials have attracted increasing attention due to their large surface-to-volume ratio and reactivity. Herein, we investigate the potential of single-layer CrSBr for gas sensing and capturing by means of first-principles calculations. We explore the adsorption behaviour of different pollutant gases (H2S, NH3, NO, NO2, CO and CO2) on this 2D ferromagnet and the impact of intrinsic defects on its magnetic properties. Interestingly, we find that Br vacancies enhance the adsorption of NH3, NO and NO2 and induce a selective frequency shift on the magnon dispersion. This work motivates the creation of novel magnonic gas sensing devices based on 2D van der Waals magnetic materials.

Recent Progress and Future Prospects of Metal‐Organic Frameworks for Adsorption, Separation and Catalytic Removal of NOx and N2O

Recent Progress and Future Prospects of Metal‐Organic Frameworks for Adsorption, Separation and Catalytic Removal of NO_x and N₂O

Synergistic catalysis of NO and chlorobenzene over Mn3O4-CeO2 catalysts: Acid sites, catalytic pathway and mechanism

Catalyst active sites and surface acidity are crucial for the synergistic catalysis of NOx and dioxins, determining the selectivity towards N2 and CO2. This study synthesized Mn3O4-CeO2 catalysts to investigate the influence of these sites on the catalytic performance for NO and chlorobenzene. Mn0.086Ce, made by the redox method, showed the highest Mn-Ce interface, achieving nearly complete conversion of chlorobenzene and NO at 180℃, with CO2 and N2 selectivity reaching about 80 % and 100 %, respectively. EPR, NH3-TPD and Py-IR analyses revealed that the Mn-Ce interface induces the formation of Lewis acid sites and oxygen vacancies, facilitating the adsorption and conversion of chlorobenzene, NH3, and NO. Mn adjacent to Lewis acid sites is the main active site, while Ce acts as an electron transfer agent. Based on the results of in-situ DRIFTS and TOF-SIMS, the possible degradation pathway for chlorobenzene was proposed and as follows: phenol, benzoquinone, maleic anhydride, propionic acid, CO2, and H2O. The NH3-SCR reaction follows the Eley-Rideal mechanism at 150–300℃.

Biaxial strain modulation of NO2 adsorption on χ3 borophene: A first-principles study

Based on first-principles calculations, the effects of applying biaxial strain to χ3 borophene and the adsorption behavior of NO2 molecule on the surface of χ3 borophene under strain are investigated. Firstly, the pristine borophene exhibits a metallic electronic structure and the thermodynamic stability of χ3 borophene is demonstrated by molecular dynamics simulations. Different adsorption sites and orientations are selected on the χ3 surface, and the optimal adsorption is found to be the S2 conformation, which has an adsorption energy of −1.589 eV. The applied biaxial strain significantly alters the electron density distribution of the χ3 borophene surface, which is predicted to be able to achieve a modification of the adsorption properties for NO2. Finally, we investigate the NO2 adsorption behavior of χ3 borophene surfaces under 1% to 5% biaxial tensile and compressive strains. Biaxial strain is found to enhance the NO2 adsorption capacity of the χ3 borophene surface, and χ3 at 3% biaxial tensile strain has the highest adsorption energy. Therefore, these results show that χ3 borophene can be a candidate material for gas sensors and theoretically guide researchers to develop more effective sensor materials for gas sensing.