Surface Reaction Research Articles

Real-time evolution characteristics and potential reactions of contaminants in commuter bus cabin air

Despite the increasing use of motor vehicles, the impact of airborne pollutants and their health risks inside public transportation, such as commuter buses, is not well understood. This study assessed air quality inside an urban commuter bus by continuously monitoring PM10, PM2.5, and CO concentrations during both driving and parking periods. Our findings revealed that the ventilation system of the bus significantly reduced the infiltration of outdoor particulate matter and water vapor. However, CO concentrations were considerably higher inside the bus than outside, primarily due to vehicular self-emission. The ineffection of the ventilation system to remove CO potentially increases long-term exposure risks for passengers. The study identified ozone as a key oxidant in the cabin. Besides vehicle emissions, C3-C10 saturated aldehydes and carbonyl compounds were detected, including acetone, propanal, and hexanal. The presence of 6-MHO, an oxidation product of squalene, suggests that passengers contribute to VOCs load through direct emissions or skin surface reactions. Additionally, human respiration was found to significantly contribute to isoprene levels, estimated at 81.7 %. This research underscores the need for further investigation into the cumulative effects of stable compounds in cabin air and provides insights for developing healthier public transportation systems.

Ultraviolet–Visible-near infrared induced photocatalytic H2 evolution over S-scheme Cu2-xSe/ZnSe heterojunction with surface plasma effects

Localized surface plasmon resonance (LSPR) effect plays a crucial role in the field of solar energy utilization. In this work, we successfully prepared a Cu2-xSe/ZnSe S-scheme heterojunction with a broad-spectrum response using the hot-injection and low-temperature water bath method. Importantly, we demonstrated that the photothermal effect induced by the LSPR of nonstoichiometric Cu2-xSe can significantly improve the slow kinetics of water splitting, resulting in an apparent activation energy reduction from 50.1 to 28.7 kJ·mol−1. This improvement is responsible for achieving the highest photocatalytic H2 evolution rate of 63.6 mmol·g−1·h−1 over 2.7 % Cu2-xSe/ZnSe under the wavelength ranged from 200 to 2500 nm, which is 3.4 and 5.6 times higher than that of ZnSe and Cu2-xSe, respectively. Furthermore, the composite exhibits a remarkable H2 production rate of 0.108 mmol·g−1·h−1 under near-infrared spectroscopy (800<λ<2500 nm), while ZnSe shows limited capability in H2 releasing. Additionally, Cu2-xSe/ZnSe demonstrates distinct photocurrent response when λ > 800 nm. The enhanced performance in H2 evolution can be attributed to the synergistic effect of LSPR-induced light absorption and S-scheme heterojunction, which not only expands the light absorption range to the near-infrared region but also facilitates hot electron injection, charge carrier separation and transfer, leading to a faster surface reaction kinetics. This study provides an effective approach for designing a broad-spectrum light responsive non-precious metal-based photothermal-assisted photocatalytic system.

Engineering FeSe2 encapsulated within carboxymethylcellulose-derived porous carbon for enhanced surface reaction kinetics in Li-ion half/full battery anodes

Encapsulation of transitional metal selenides within the porous nanocarbon network has been regarded as a highly advantageous strategy for improving anode performance in terms of capacity, cycle-to-cycle stability, and operational durability for Li+ storage. Herein, a mildly sol-gel process and in-situ self-transformation strategy were employed to fabricate FeSe2 encapsulated within eco-friendly carboxymethylcellulose (CMC)-derived porous carbon, achieving a feasible capacity and relatively durable structure. The FeSe2@PC anode with square-built Li+/e− diffusion pathway exhibits a comparatively high reversible capacity of up to 758 mAh g−1 at 0.1 A g−1 and relatively good cycling stability, with a capacity retention of 83% after 500 cycles at 1 A g−1 in half cells. Furthermore, FeSe2@PC//LiMn2O4 full cells also demonstrate relatively outstanding electrochemical performance when paired with a LiMn2O4 cathode. The nanoconfinement electrode configuration, featuring interconnected external/internal carbon shell/FeSe2 nanoparticles, not only provides good electrical conductivity and buffering capacity for volume changes but also facilitates electrolyte infiltration and surface/near-surface interactions between electroactive FeSe2 and Li+. Kinetic analysis through cyclic voltammetry, galvanostatic intermittent titration technique, and electrochemical impedance spectroscopy indicates exceptional Li+/e− transport kinetics. Employing green and eco-friendly materials in energy storage is crucial for advancing sustainable energy technologies, and the engineered FeSe2@PC nanocomposite demonstrated in this study offers promising potential towards this objective.

Comprehensive modeling of ignition and combustion of multiscale aluminum particles under various pressure conditions

The ignition and combustion of aluminum particles are crucial to achieve optimal energy release in propulsion and power systems within a limited residence time. This study seeks to develop theoretical ignition and combustion models for aluminum particles ranging from 10 nm to 1000 μm under wide pressure ranges of normal to beyond 10 MPa. Firstly, a parametric analysis illustrates that the convective heat transfer and heterogeneous surface reaction are strongly influenced by pressure, which directly affects the ignition process. Accordingly, the ignition delay time can be correlated with pressure through the pb relationship, with b increasing from –1 to –0.1 as the system transitions from the free molecular regime to the continuum regime. Then, the circuit comparison analysis method was used to interpret an empirical formula capable of predicting the ignition delay time of aluminum particles over a wide range of pressures in N2, O2, H2O, and CO2 atmospheres. Secondly, an analysis of experimental data indicates that the exponents of pressure dependence in the combustion time of large micron-sized particles and nanoparticles are –0.15 and –0.65, respectively. Further, the dominant combustion mechanism of multiscale aluminum particles was quantitatively demonstrated through the Damköhler number (Da) concept. Results have shown that aluminum combustion is mainly controlled by diffusion as Da > 10, by chemical kinetics when Da ≤ 0.1, and codetermined by both diffusion and chemical kinetics when 0.1 < Da ≤ 10. Finally, an empirical formula was proposed to predict the combustion time of multiscale aluminum particles under high pressure, which showed good agreement with available experimental data.

INFLUENCE OF DESIGN AND OPERATIONAL FACTORS ON THE STABILITY OF THE CAR WITH TRAILER OF CATEGORY O2 DURING BRAKING MODE

In recent years, enterprises and private manufacturers in Ukraine have mastered the production of a wide range of towed vehicles. Significant attention is given to the issues of road safety for road trains, particularly those of category M1, which have found widespread use not only among state and private enterprises but also among amateur motorists. Ensuring the safety of such road trains is a pressing task. The movement characteristics of a road train fundamentally differ from those of a single vehicle. This difference is explained by the presence of additional forces in the articulated connections of the vehicle components, as well as the forces and moments acting on its individual components, which influence the movement of the vehicle as a whole. This influence is particularly noticeable during the braking of a road train, which can be accompanied by the folding of components and a loss of vehicle stability. Ensuring the safety of such road trains is a pressing task that requires a more detailed analysis of the impact of the distribution of braking forces on the stability of the road train’s movement. Such research was conducted on a spatial mathematical model of the road train. To determine the longitudinal and lateral forces acting on the wheels of a road train during braking, the normal reactions of the support surface on the wheels of the vehicle and trailer were determined. These reactions, along with the specific braking forces, determine the braking forces acting on the wheels of the vehicle and trailer. For example, with a deceleration of 6.0 m/s², the normal reaction of the support surface on the twin axle of the trailer decreases by 25%. In the absence of an anti-lock braking system in the trailer’s brake drive, wheel lockup and loss of road train stability are possible. Therefore, it is advisable to brake the road train with decelerations not exceeding 4.0 m/s². In this case, the initial braking speed that ensures the stability of the road train’s movement is higher than its maximum speed. When changing the trailer’s load while the vehicle’s load remains unchanged at a speed of 25 m/s, the road train remains stable throughout the entire range of the trailer’s total mass variation, whereas at a speed of 30 m/s, the critical mass of the trailer remains at 2500 kg. This is explained by the fact that the trailer’s mass affects the magnitude of the maximum braking force created by the braking system and the braking force that can be realized. The loading of the trailer, particularly the side loading of its wheels, is very important as it can lead to uneven braking forces on the trailer’s axles. It is shown that with the nominal loading of the vehicle and trailer, increasing the unevenness of the braking forces on the trailer’s axles up to 30% reduces the initial braking speed, which still ensures the stability of the road train’s movement, by almost half from 35.3 to 19.7 m/s. Therefore, the unevenness of the braking forces on the trailer’s axles should be limited to 15%. This will ensure the stability of the road train’s movement and the safety of its operation. Keywords: аutomobile, trailer, road train, side and axle load, braking, initial speed, movement stability.

Ni-NCDs promoted photocatalytic benzylamine oxidation coupled hydrogen production in Cu-In-Zn-S/WO3·H2O Z-scheme heterojunction

The construction of Z-scheme heterojunction is important for efficient photocatalytic organic oxidation coupled hydrogen production. However, current methods suffer from poor synergy of charge extraction and surface reactions. In this study, we combined Cu-In-Zn-S (CIZS) quantum dots with WO3·H2O (WO) nanosheets to form a Z-scheme heterojunction, which was further modified with bifunctional N-doped carbon dots (NCDs) to improve charge extraction and abundant Ni sites for hydrogen evolution. The unique 0D/2D/0D CIZS/WO/Ni-NCDs heterojunction resulted in a hydrogen production rate of 4.261 mmol g−1 h−1, with ascorbic acid, 8.06 times higher than that of CIZS. In addition, the selectivity of N-benzylidenebenzylamine from benzylamine oxidation reaction has been increased from 31.65 % to 73.34 %. This improvement can be attributed to the efficient charge separation, transfer, and surface reactions accelerated by the multifunctional Ni-NCDs. A series of photoelectrochemical tests and radical scavenging experiments confirmed the Z-scheme photocatalytic process and the important roles of superoxide radicals and holes. Photo-induced electrocatalysis tests further confirmed the accelerated hydrogen evolution reaction in the presence of Ni-NCDs. Furthermore, time-resolved photoluminescence test demonstrated that the synergies of NCDs and Ni significantly extended the charge carrier lifetime. These findings provide valuable insights into efficient hydrogen production through the modulation of Z-scheme heterojunctions using bifunctional metal-carbon dots.

Synergistic degradation of metronidazole and penicillin G in aqueous solutions using AgZnFe2O4@chitosan nano-photocatalyst under UV/persulfate activation

In recent years, the persistence of pharmaceutical contaminants like metronidazole (MNZ) and penicillin G (PG) in water bodies has become a major environmental concern. The present research studied the simultaneous degradation of MNZ and PG utilizing an AgZnFe2O4@Ch catalyst generated through the co-precipitation technique as an effective stimulator for persulfate (PS) in the existence of UV light. The structure of the AgZnFe2O4@Ch catalyst was characterized using X-ray powder diffraction, Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, vibrating-sample magnetometer, and energy dispersive spectroscopy mapping. After 50 minutes of reaction time under the ideal operating conditions, which included 0.4 g/L of catalyst, 4 mM of PS, 5 mg/L of MNZ and PG, and a pH of 5, the highest MNZ and PG degradation of 81.5 % and 82.3 % were obtained. Statistical parameters, including the R2 values of 0.985 for MNZ and 0.981 for PG, indicate a very good agreement between the predicted and observed values. The Garson's method analysis revealed that PS dosage had the greatest impact on MNZ degradation, while the initial concentration of PG exerted the most significant influence on PG degradation. The Langmuir-Hinshelwood model has surface reaction rate constants (Kc) of 0.954 (mg/L.min) and adsorption equilibrium constants (KL-H) of 0.032 (L/mg) for both antibiotics, respectively. The claimed mechanism was illustrated by the free radical scavenging studies, which demonstrated that the SO•4- radicals were the main radicals involved in the degradation of MNZ and PG. A last investigation of the catalyst's regeneration revealed that it had satisfactory chemical stability after five cycles of usage and regeneration using chemical approaches.

Structural and chemical evolutions of a magnesium vanadium oxide cathode under electrochemical cycling in magnesium batteries

The design of cathode materials that remain chemically and structurally stable during repetitive ion insertion and extraction poses a significant challenge in developing multivalent batteries. The cycling stability of traditional metal oxide-based cathode is challenged by sluggish diffusion of multivalent cations and parasitic reactivity at interfacial regimes, including the cathode electrolyte interphase layer (CEI). Understanding the reactions at the cathode-electrolyte interface, particularly those induced by non-stoichiometric surface layers, is a crucial design parameter for both cathode materials and electrolytes. In this study, we employed multimodal analysis, including in situ and ex situ X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) to examine the surface reactions and subsequent structural and chemical evolutions of the CEI on high voltage magnesium vanadium oxide (MgV2O4) spinel cathode during the Mg2+ insertion/extraction processes. The results revealed that the presence of non-stoichiometric surface layers in the magnesium vanadium oxide cathode drive the decomposition of bis(trifluoromethanesulfonyl)imide (TFSI-) anion, leading to the formation of the CEI layer. The CEI layer could inhibit the Mg2+ ion transfer processes. Accompanying this reactivity-driven degradation, the magnesium vanadium oxide cathode undergoes pulverization, forming clusters of nanosized particles. This process likely improves cycling ability by creating new intercalation sites and shortening the diffusion pathway for the Mg2+ cations. This study demonstrates that controlling surface stoichiometry and engineering morphological properties are critical design parameters for high performance cathodes for multivalent batteries.

Degradation Processes of Two Compound Layers on Nitrided Surfaces During the Wear Test by “Block on Hot Al Cylinder”

The results obtained in the study help to explain the degradation process of the nitrided steel compound layer. Compound layers with different properties on gas-nitrided H10 tool steel blocks were tested for wear with “block on hot Al cylinder”. Degradation processes were observed on both compound layers with different properties and at three contact pressures. In order to observe the degradation processes in the compound layers, the wear tests were interrupted at various fixed time intervals and the resulting changes were closely monitored. The comprehensive analysis highlighted the complexity of the degradation process in the compound layers and emphasized the existence of complex relationships between the above-mentioned parameters. The reaction of the nitrided steel surface with hot Al is more pronounced in areas with lower contact pressure, while adhesive removal and furrow formation are pronounced in areas with low and medium contact pressure. This process begins with a sufficient density of the areas where islands of adhesive removal are located, their enlargement during the test, the breaking up of the walls between them, and finally the removal of the compound layer in the sliding direction, which appears as furrowing in the final phase of wear.

A Comprehensive Investigation of Methanol Electrooxidation on Copper Anodes: Spectroelectrochemical Insights and Energy Conversion in Microfluidic Fuel Cells.

Here, we comprehensively investigated methanol electrooxidation on Cu-based catalysts, allowing us to build the first microfluidic fuel cell (μFC) equipped with a Cu anode and a metal-free cathode that converts energy from methanol. We applied a simple, fast, small-scale, and surfactant-free strategy for synthesizing Cu-based nanoparticles at room temperature in steady state (ST), under mechanical stirring (MS), or under ultrasonication (US). The morphology evaluation of the Cu-based samples reveals that they have the same nanoparticle (NP) needle-like form. The elemental mapping composition spectra revealed that pure Cu or Cu oxides were obtained for all synthesized materials. In addition to having more Cu2O on the surface, sample US had more Cu(OH)2 than the others, according to X-ray diffractograms and X-ray photoelectron spectroscopy. The sample US is less carbon-contaminated because of the local heating of the sonic bath, which also enhances the cleanliness of the Cu surface. The activity of the Cu NPs was investigated for methanol electrooxidation in an alkaline medium through electrochemical and spectroelectrochemical measurements. The potentiodynamic and potentiostatic experiments showed higher current densities for the NPs synthesized in the US. In situ FTIR experiments revealed that the three synthesized NP materials eletcrooxidize methanol completely to carbonate through formate. Most importantly, all pathways were led without detectable CO, a poisoning molecule not found at high overpotentials. The reaction path using the US electrode experienced an additional round of formate formation and conversion into carbonate (or CO2 in the thin layer) after 1.0 V (vs. Ag/Ag/Cl), suggesting improved catalysis. The high activity of NPs synthesized in the US is attributed to effective dissociative adsorption of the fuel due to the site's availability and the presence of hydroxyl groups that may fasten the oxidation of adsorbates from the surface. After understanding the surface reaction, we built a mixed-media μFC fed by methanol in alkaline medium and sodium persulfate in acidic medium. The μFC was equipped with Cu NPs synthesized in ultrasonic-bath-modified carbon paper as the anode and metal-free carbon paper as the cathode. Since the onset potential for methanol electrooxidation was 0.45 V and the reduction reaction revealed 0.90 V, the theoretical OCV is 0.45 V, which provides a spontaneous coupled redox reaction to produce power. The μFC displayed 0.56 mA cm-2 of maximum current density and 26 μW cm-2 of peak power density at 100 μL min-1. This membraneless system optimizes each half-cell individually, making it possible to build fuel cells with noble metal-free anodes and metal-free cathodes.

T‐Nb2O5 Surface Coating Enables a Stable Zinc Anode

The surface reactions of zinc anode, including dendrite formation, corrosion, and passivation, hinder the aqueous zinc‐ion batteries. Surface engineering is one effective strategy for zinc protection. Herein, a high dielectric constant and stable and easily prepared T‐Nb2O5 first demonstrate as the surface coating for zinc anode. The hydrophilic T‐Nb2O5 coating can restrict the migration path of zinc ions and induce the bottom‐up orderly deposition of zinc ions instead of disordered deposition. The T‐Nb2O5 coating zinc anode (T‐Nb2O5/Zn) shows improved electrochemical performance. The voltage of T‐Nb2O5/Zn symmetric cell is stable in the long cycle of 1600 h and about 50 mV in the first 20 h and 25 mV in the last 20 h. After 150 cycles, the discharge capacity of T‐Nb2O5/Zn || MnO2 full battery is 209 mAh g−1, showing a capacity retention rate of 94%. The design of T‐Nb2O5 coating provides an attractive strategy for stable and reversible aqueous zinc metal batteries.

NiMo₂S₄-VS₂ heterostructure on nickel Foam: A promising electrocatalyst for alkaline oxygen evolution reaction

Oxygen Evolution Reaction (OER) is a slow process; therefore, improved kinetics require catalytic active centers and higher charge transfer capacities. In the present study, a novel heterostructure made of nickel molybdenum sulfide and vanadium disulfide supported on nickel foam (NiMo2S4-VS2/NF) substrate is fabricated using a single-step hydrothermal process. The structural, morphological, elemental, and textural properties of the fabricated materials are confirmed via various analytical techniques. Furthermore, at the current density of 10 mA cm−2, the observed overpotentials was approximately 318 mV corresponding to an OER in 1 M potassium hydroxide electrolyte. It also shows a lower Tafel slope of 78 mV/dec with large turnover frequency of 2.56 s−1. The resulting NiMo2S4-VS2/NF showed enhanced charge transfer properties and frequent integrated active sites. Hence the remarkable activity of this catalyst is significantly influenced by the synergistic effect of these combined features and resulted in an efficient overall water splitting. This was ascribed to NiMo2S4 which increases OER at the anode by providing active sites for oxidizing water molecules. In NiMo2S4, Mo and S elements aid to maintain active sites and accelerate reaction kinetics, while Ni sites operate as electrocatalytic efforts for water oxidation. In general, VS2 promotes hydrogen atom recombination into molecular hydrogen while also encouraging HER at the cathode via hydrogen atom adsorption. In general, NiMo2S4-VS2/NF is a suitable option for water splitting applications due to the close proximity of these two components within the structure of the catalyst, which enables charge transfer and surface reactions and also allow for effective OER. This unique approach for designing the catalyst and engineering the heterointerface is a promising strategy to develop novel and efficient OER catalysts.

Strategy for the Preparation of ZnS/ZnO Composites Derived from Metal-Organic Frameworks toward Lithium Storage.

The synergistic effect between multicomponent electrode materials often makes them have better lithium storage performance than single-component electrode materials. Therefore, to enhance surface reaction kinetics and encourage electron transfer, using multicomponent anode materials is a useful tactic for achieving high lithium-ion battery performance. In this article, ZnS/ZnO composites were synthesized by solvothermal sulfidation and calcination, with the utilization of metal-organic frameworks acting as sacrificial templates. From the point of material design, both ZnS and ZnO have high theoretical specific capacities, and the synergistic effect of ZnS and ZnO can promote charge transport. From the perspective of electrode engineering, the loose porous carbon skeleton that results from the calcination of metal-organic frameworks can enhance composite material conductivity as well as full electrolyte penetration and the area of contact between the electrolyte and active material, all of which are beneficial to enhancing lithium storage performance. As expected, ZnS/ZnO anode materials displayed remarkably high specific capacities and outstanding performance at different rates. Combining material design and electrode engineering, this paper provides another idea for preparing anode materials with excellent lithium storage properties.

Interactions between organic matter and alkaline minerals in bauxite residue: implication for soil restoration.

Ecological restoration of bauxite residue has received extensive attention, and organic matter plays a crucial role in the soil formation process of bauxite residue. However, the interaction between organic matter and alkaline minerals in bauxite residue is not well understood. In this work, molecular spectroscopic techniques combined with isothermal titration calorimetry (ITC) were employed to investigate the interactions between humic acid (HA) and four representative alkaline minerals in bauxite residue (calcite, garnet, sodalite, and cancrinite). The results show that the adsorption processes of HA onto calcite and garnet were primarily governed by monolayer surface adsorption and controlled by surface reactions, which were different for sodalite and cancrinite. Both garnet and cancrinite had strong binding affinities with fluorescent HA, while cancrinite only bound with a small fraction of HA. In contrast, the bindings of calcite and sodalite with fluorescent HA were weak. The ITC results indicate distinct thermodynamic properties of different alkaline minerals in the interaction with HA. The molar enthalpy of calcite was - 45.88kJ/mol, which was much higher than those of garnet, sodalite, and cancrinite, suggesting that calcite exhibited a relatively uniform interaction mechanism with HA dominated by enthalpy change, while the others showed heterogeneous entropy-driven mechanisms. The findings contribute to a better understanding on the microscale connections between organic matter and alkaline minerals in bauxite residue.

Ligand-functionalized surfaces for chemoselective heterogeneous catalysis

Selectivity of multi-pathway surface reactions depends on subtle differences in the activation barriers of competing reactive processes, which is difficult to control. One of the most promising strategies to overcome this problem is to introduce a specific selective interaction between the reactant and the catalytically active site, directing the chemical transformations towards the desired route. This interaction can be imposed via functionalization of a solid catalyst with organic ligands, promoting the desired pathway via steric constrain and/or electronic effects. The microscopic-level understanding of the underlying surface processes is an important prerequisite for rational design of such new class of ligand-functionalized catalytic materials. In this perspective, we present an overview over our recent mechanistic studies on heterogeneous Pd(111) catalysts functionalized with different types of organic ligands for chemoselective hydrogenation of a,b-unsaturated aldehyde acrolein. Employing a combination of real space microscopic (STM) and in operando spectroscopic (IRAS) surface sensitive techniques, we show that self-ordered active ligand layers are formed under operational conditions and identify their chemical nature and the geometric arrangement on the surface turning over. Deposition of a ligand layer renders Pd highly active and nearly 100 % selective toward propenol formation by promoting acrolein adsorption in a specific adsorption configuration via the O atom of the C = O bond. In this adsorption configuration, acrolein can be hydrogenated first to the desired reaction intermediate propenoxy species followed by formation of the target product propenol. Both the reaction intermediate and the final product propenol as well as their time evolution were identified by IRAS and gas phase analysis via quadrupole mass spectrometry (QMS). Particular focus of these studies was on the role of geometric and electronic effects imposed by specific functional groups purposefully introduced in the ligand layer. Obtained atomistic-level insights into the formation and dynamic evolution of the active ligand layer under operational conditions as well as into the role of geometric vs. electronic effects imposed by the ligand provide important input required for controlling chemoselectivity by purposeful surface functionalization.

IrSn Bimetallic Clusters Confined in MFI Zeolites for CO Selective Catalytic Reduction of NOx in the Presence of Excess O2.

We developed a simple strategy for preparing IrSn bimetallic clusters encapsulated in pure silicon zeolites via a one-pot hydrothermal synthesis by using diethylamine as a stabilizing agent. A series of investigations verified that metal species have been confined successfully in the inner of MFI zeolites. IrSn bimetallic cluster catalysts were efficient for the CO selective catalytic reduction of NOx in the presence of excess O2. Furthermore, the 13CO temperature-programmed surface reaction results demonstrated that NO2 and N2O could form when most of the CO was transformed into CO2 and that Sn modification could passivate CO oxidation on the IrSn bimetallic clusters, leading to more reductants that could be used for NOx reduction at high temperatures. Furthermore, SO2 can also influence the NOx conversion by inhibiting the oxidation of CO. This study provides a new strategy for preparing efficient environmental catalysts with a high dispersion of metal species.

Atomic dynamics of electrified solid-liquid interfaces in liquid-cell TEM.

Electrified solid-liquid interfaces (ESLIs) play a key role in various electrochemical processes relevant to energy1-5, biology6 and geochemistry7. The electron and mass transport at the electrified interfaces may result in structural modifications that markedly influence the reaction pathways. For example, electrocatalyst surface restructuring during reactions can substantially affect the catalysis mechanisms and reaction products1-3. Despite its importance, direct probing the atomic dynamics of solid-liquid interfaces under electric biasing is challenging owing to the nature of being buried in liquid electrolytes and the limited spatial resolution of current techniques for in situ imaging through liquids. Here, with our development of advanced polymer electrochemical liquid cells for transmission electron microscopy (TEM), we are able to directly monitor the atomic dynamics of ESLIs during copper (Cu)-catalysed CO2 electroreduction reactions (CO2ERs). Our observation reveals a fluctuating liquid-like amorphous interphase. It undergoes reversible crystalline-amorphous structural transformations and flows along the electrified Cu surface, thus mediating the crystalline Cu surface restructuring and mass loss through the interphase layer. The combination of real-time observation and theoretical calculations unveils an amorphization-mediated restructuring mechanism resulting from charge-activated surface reactions with the electrolyte. Our results open many opportunities to explore the atomic dynamics and its impact in broad systems involving ESLIs by taking advantage of the in situ imaging capability.

Tuning Dynamic Structural Evolution of Bi24O31Cl10 for Enhancing Piezo-Photocatalytic Nitrogen Oxidation to Nitrate.

Direct nitrogen oxidation into nitrate under ambient conditions presents a promising strategy for harsh and multistep industrial processes. However, the dynamic structural evolution of active sites in surface reactions constitutes a highly intricate endeavor and remains in its nascent stage. Here, we constructed a Bi24O31Cl10 material with moiré superlattice structure (BCMS) for direct piezo-photocatalytic oxidation of nitrogen into nitrate. Excitingly, BCMS achieved excellent nitric acid production (15.44 mg g-1 h-1) under light and pressure conditions. Detailed experimental results show that the unique structure extracts the local strain tensor from the constricting Bi-Bi bond and Bi-O bond for internal structural reconstruction, which promotes the formation of electron and reactive molecule vortexes to facilitate charge transfer as well as N2 and O2 adsorption. Ultimately, these initiatives strengthen electron exchange between the superoxide radical and nitrogen as well as the binding strength of multiple intermediates, which swayingly adjusts the reaction path and energy barriers.

UV activated formaldehyde gas sensing based on gold decorated ZnO@ In2O3 hollow nanospheres at room temperature

Using uniform carbon nanospheres as sacrificial templates, gold nanoparticle-modified ZnO@ In2O3 hollow nanospheres with controlled dimensions and porous architectures were successfully synthesized through water bath, hydrothermal and chemical reduction methods. Gas sensing evaluation revealed that the Au-decorated ZnO@ In2O3 hollow nanostructures exhibited a dramatically amplified response up to 14.8 when exposed to 10 ppm formaldehyde analyte at room temperature. Furthermore, multifaceted performance benefits of Au-decorated ZnO@ In2O3 over single-phase ZnO, Au-ZnO, ZnO@ In2O3 heterojunction-based composites were observed, including excellent selectivity towards formaldehyde even in complex gas mixtures; tremendous sensitivity enhancement stemming from synergies between efficient gas diffusion through hollow heterojunction nanospheres and accelerated surface reactions at catalytically-active Au sites; and rapid, fully-reversible response/recovery time of 32 s and 42 s, respectively. In-depth investigations were conducted into the fundamental sensing mechanisms enabling formaldehyde detection using AC impedance spectroscopy, in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), and density functional theory (DFT) computational modeling analyses.

VO2/VS4 heterostructures structure–modified 3D reduced graphene oxide aerogel as an advanced host for lithium–sulfur batteries

Lithium–sulfur batteries face challenges including volume expansion, slow reaction kinetics, and shuttle effects. To overcome these limitations, we utilized a combination of vanadium–based heterostructures and conductive porous reduced graphene oxide aerogels to improve charge transfer kinetics. The researchers synthesised vanadium–based reduced graphene oxide aerogels (VO2/VS4@RGO) via tube furnace calcination and a one–step hydrothermal method. Vanadium–based heterostructures were electrostatically adsorbed onto the surface of three–dimensional reduced graphene oxide aerogels. The fibrous structure of VO2/VS4 promoted charge transfer, while the high conductivity of VS bonds lowered the surface reaction barrier. The VO2/VS4@RGO–3/S cathode exhibited outstanding cycling stability at a high discharge rate of 2C, demonstrating an initial discharge specific capacity of 771.94 mAh g−1 and an average decay rate of 0.071 % after 700 cycles. It also maintained excellent electrochemical performance under high sulfur loading.