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Surface hydroxyl groups commonly exist on the catalyst and present a significant role in the catalytic reaction. Considering the lack of systematical researches on the effect of the surface hydroxyl group on reactant molecule activation, the PtOx/TiO2and PtOx–y(OH)y/TiO2catalysts were constructed and studied for a comprehensive understanding of the roles of the surface hydroxyl group in the oxidation of volatiles organic compounds. The PtOx/TiO2formed by a simple treatment with nitric acid presented greatly enhanced activity for toluene oxidation in which the turnover frequency of toluene oxidation on PtOx/TiO2was around 14 times as high as that on PtOx–y(OH)y/TiO2. Experimental and theoretical results indicated that adsorption/activation of toluene and reactivity of oxygen atom on the catalyst determined the toluene oxidation on the catalyst. The removal of surface hydroxyl groups on PtOxpromoted strong electronic coupling of the Pt 5d orbital in PtOxand C 2p orbital in toluene, facilitating the electron transfers from toluene to PtOxand subsequently the adsorption/activation of toluene. Additionally, the weak Pt–O bond promoted the activation of surface lattice oxygen, accelerating the deep oxidation of activated toluene. This study clarifies the inhibiting effect of surface hydroxyl groups on PtOxin toluene oxidation, providing a further understanding of hydrocarbon oxidation.

NiFe layered double hydroxides (NiFe-LDH) exhibited an outstanding performance and promising application potential for removing ozone. However, the effect of interlayer anions on ozone removal remains ambiguous. Here, a series of NiFe-LDH with different interlayer anions (F–, Cl–, Br–, NO3–, CO32–, and SO42–) were prepared to investigate the effect of the interlayer anion on ozone removal for the first time. It was found that the interlayer anions are a key factor affecting the water resistance of the NiFe-LDH catalyst under moist conditions. NiFe-LDH-CO32–exhibited the best water resistance, which was much better than that of NiFe-LDH containing other interlayer anions. The in situ DIRFTS demonstrates that the carbonates in the interlayer of NiFe-LDH-CO32–will undergo coordination changes through the interaction with water molecules under moist conditions, exposing new metal sites. As a result, the newly exposed metal sites could activate water molecules into hydroxyl groups that act as active sites for catalyzing ozone decomposition. This work provides a new insight into the interlayer anions of LDH, which is important for the design and development of LDH catalysts with excellent ozone removal properties.

Nitrate photolysis is a vital process in secondary NOx release into the atmosphere. The heterogeneous oxidation of SO2due to nitrate photolysis has been widely reported, while the influence of SO2on nitrate photolysis has rarely been investigated. In this study, the photolysis of nitrate on different substrates was investigated in the absence and presence of SO2. In the photolysis of NH4NO3on the membrane without mineral oxides, NO, NO2, HONO, and NH3decreased by 17.1, 6.0, 12.6, and 57.1% due to the presence of SO2, respectively. In the photolysis of NH4NO3on the surface of mineral oxides, SO2also exhibited an inhibitory effect on the production of NOx, HONO, and NH3due to its reducibility and acidic products, while the increase in surface acidity due to the accumulation of abundant sulfate on TiO2and MgO promoted the release of HONO. On the photoactive oxide TiO2, HSO3–, generated by the uptake of SO2, could compete for holes with nitrate to block nitrate photolysis. This study highlights the interaction between the heterogeneous oxidation of SO2and nitrate photolysis and provides a new perspective on how SO2affects the photolysis of nitrate absorbed on the photoactive oxides.

Asymmetrically adhesive hydrogel patch with robust wet tissue adhesion simultaneously anti‐postoperative adhesion is essential for clinical applications in internal soft‐tissue repair and postoperative anti‐adhesion. Herein, inspired by the lubricative role of serosa and the underwater adhesion mechanism of mussels, an asymmetrically adhesive hydrogel Janus patch is developed with adhesion layer (AL) and anti‐adhesion layer (anti‐AL) through an in situ step‐by‐step polymerization process in the mold. The AL exhibits excellent adhesion to internal soft‐tissues. In contrast, the anti‐AL demonstrated ultralow fouling property against protein and fibroblasts, which hinders the early and advanced stages of development of the adhesion. Moreover, the Janus patch simultaneously promotes tissue regeneration via ROS clearance capability of catechol moieties in the AL. Results from in vivoexperiments with rabbits and rats demonstrate that the AL strongly adheres to traumatized tissue, while the anti‐AL surface demonstrate efficacy in preventing of post‐abdominal surgery adhesions in contrast to clinical patches. Considering the advantages in terms of therapeutic efficacy and off the shelf, the Janus patch developed in this work presents a promise for preventing postoperative adhesions and promoting regeneration of internal tissue defects. A Janus patch with an adhesion layer (AL) and anti‐adhesion layer (anti‐AL) is developed, inspired by serosa and mussel. The anti‐AL layer, featuring a zwitterioic polymer hydrogel with N‐acryloyl glycinamide, prevents adhesion. The AL layer, using p(DPAMA‐co‐SBMA‐co‐NAGA), ensures adhesiveness and strength, while catechol moieties enhance tissue regeneration by scavenging ROS.

In previous work, we successfully prepared a NiFe-layered double hydroxide (LDH) with superior activity and stability for catalytic ozone decomposition, which fundamentally avoids deactivation under high-humidity conditions. However, the role of the metal elements (M2+and M3+) in LDH catalysts is not clear. Here, LDH materials containing different metals (NiFe, NiAl, NiMn, CoFe, and MgFe) were prepared by a simple co-precipitation method. It was found that the LDHs containing Ni2+exhibited catalytic performance far superior to that of Co2+and Mg2+for ozone elimination, and NiFe-LDH had the best activity and stability among LDH materials prepared in this study. The NiFe-LDH can maintain 78% catalytic activity within 144 h at room temperature, even under a relative humidity of 65% and a space velocity of 840 L·g–1·h–1. Physicochemical characterizations demonstrated that chemical stability in an oxidizing atmosphere and the synergic role of M2+and M3+ions are crucial. The result of density functional theory calculation showed that the synergic role of Ni2+and Fe3+weakens the interaction between O and H in the O–H bond, which effectively lowers the reaction barrier of ozone decomposition compared with MgFe-LDH.

Groundwater plays a dominant role in the eco-environmental protection of arid and semi-arid regions. Understanding the sources and mechanisms of groundwater recharge, the interactions between groundwater and surface water and the hydrogeochemical evolution and transport processes of groundwater in the Longdong Loess Basin, Northwest China, is of importance for water resources management in this ecologically sensitive area. In this study, 71 groundwater samples (mainly distributed at the Dongzhi Tableland and along the Malian River) and 8 surface water samples from the Malian River were collected, and analysis of the aquifer system and hydrological conditions, together with hydrogeochemical and isotopic techniques were used to investigate groundwater sources, residence time and their associated recharge processes. Results show that the middle and lower reaches of the Malian River receive water mainly from groundwater discharge on both sides of valley, while the source of the Malian River mainly comes from local precipitation. Groundwater of the Dongzhi Tableland is of a HCO3-Ca-Na type with low salinity. The reverse hydrogeochemical simulation suggests that the dissolution of carbonate minerals and cation exchange between Ca2+, Mg2+and Na+are the main water-rock interactions in the groundwater system of the Dongzhi Tableland. The δ18O (from −11.70‰ to −8.52‰) and δ2H (from −86.15‰ to −65.75‰) values of groundwater are lower than the annual weighted average value of precipitation but closer to summer-autumn precipitation and soil water in the unsaturated zone, suggesting that possible recharge comes from the summer-autumn monsoonal heavy precipitation in the recent past (≤220 a). The corrected 14C ages of groundwater range from 3,000 to 25,000 a old, indicating that groundwater was mainly from precipitation during the humid and cold Late Pleistocene and Holocene periods. Groundwater flows deeper from the groundwater table and from the center to the east, south and west of the Dongzhi Tableland with estimated migration rate of 1.29–1.43 m/a. The oldest groundwater in the Quaternary Loess Aquifer in the Dongzhi Tableland is approximately 32,000 a old with poor renewability. Based on the δ18O temperature indicator of groundwater, we speculate that temperature of the Last Glacial Maximum in the Longdong Loess Basin was 2.4°C–6.0°C colder than the present. The results could provide us the valuable information on groundwater recharge and evolution under thick loess layer, which would be significative for the scientific water resources management in semi-arid regions.

For supported noble metal catalysts, the properties of the support have a great influence on the state of the noble metals. Herein, we chose Al2O3as a model to find a simple method for regulating the types and related contents of surface OH groups. The treated Al2O3supports with different content of terminal OH groups were utilized to prepare a series of Pt-Na/Al2O3samples, which were evaluated by formaldehyde (HCHO) catalytic oxidation. Characterization results illustrated that terminal OH groups were beneficial to Pt and Na anchoring. Terminal OH groups with the participation of Na species dispersed Pt atomically, which promoted the formation of bridging OH groups between Na and Al, showing excellent performance in the decomposition of formate species. The strategy of controlling surface OH groups provided a new insight to regulate supports which further changed the state of noble metals and is beneficial to the synthesis of efficient heterogeneous catalysts.

Ozone (O3) removal has important implications for environmental protection and human health, and Ag-Mn catalysts have shown promising O3decomposition. Catalysts with Ag supported on porous cube-like α-Mn2O3(Ag/Mn-C) with high utilization of Ag were prepared by the impregnation method and showed excellent O3decomposition activity. Physicochemical characterizations demonstrated that metallic Ag nanoparticles (Agn0) were mainly anchored on manganese vacancies, forming Ag–O–Mn bonds between Agn0and α-Mn2O3-C. The abundant manganese vacancies of α-Mn2O3-C can lead to Agn0with a smaller particle size and more uniform dispersion, thereby resulting in markedly enhanced O3decomposition performance compared to Agn0with a large particle size and uneven distribution on rod-like α-Mn2O3(Ag/Mn-R). Under a relative humidity of 65% and a space velocity of 1,110,000 h–1, the conversion of 40 ppm O3over the 2%Ag/Mn-C catalyst within 6 h (98%) at 30 °C was more than twice as high as that of the 2%Ag/Mn-R catalyst (42%). The study provides guidance for the design of highly efficient Ag-based catalysts and the understanding of the microstructure of supported catalysts.

Nitrates formed on mineral dust through heterogeneous reactions in high NOxareas can undergo photolysis to regenerate NOxand potentially interfere in the photochemistry in the downwind low NOxareas. However, little is known about such renoxification processes. In this study, photolysis of various nitrates on different mineral oxides was comprehensively investigated in a flow reactor and in situ diffuse reflectance Fourier-transform infrared spectroscopy (in situ DRIFTS). TiO2was found much more reactive than Al2O3and SiO2with both NO2and HONO as the two major photolysis products. The yields of NO2and HONO depend on the cation basicity of the nitrate salts or the acidity of particles. As such, NH4NO3is much more productive than other nitrates like Fe(NO3)3, Ca(NO3)2, and KNO3. SO2and water vapor promote the photodegradation by increasing the surface acidity due to the photoinduced formation of H2SO4/sulfate and H+, respectively. O2enables the photo-oxidation of NOxto regenerate nitrate and thus inhibits the NOxyield. Overall, our results demonstrated that the photolysis of nitrate can be accelerated under complex air pollution conditions, which are helpful for understanding the transformation of nitrate and the nitrogen cycle in the atmosphere.

Secondary organic aerosol (SOA) plays a critical role in sustained haze pollution in megacities. Traditional observation of atmospheric aerosols usually analyzes the ambient organic aerosol (OA) but neglects the SOA formation potential (SOAFP) of precursors remaining in ambient air. Knowledge on SOAFP is still limited, especially in megacities suffering from frequent haze. In this study, the SOAFP of ambient air in urban Beijing was characterized at different pollution levels based on a two-year field observation using an oxidation flow reactor (OFR) system. Both OA and SOAFP increased as a function of ambient pollution level, in which increasing concentrations of precursor volatile organic compounds (VOCs) and decreasing atmospheric oxidation capacity were found to be the two main influencing factors. To address the role of the atmospheric oxidation capacity in SOAFP, a relative OA enhancement ratio (EROA= 1 + SOAFP/OA) and the elemental composition of the OA were investigated in this study. The results indicated that the atmospheric oxidation capacity was weakened and resulted in higher SOAFP on more polluted days. The relationship found between SOAFP and the atmospheric oxidation capacity could be helpful in understanding changes in SOA pollution with improving air quality in the megacities of developing countries.

The NO–NO2cycle determines the formation of O3and hence plays a critical role in the oxidizing capacity of troposphere. Traditional view concluded that the heterogeneous oxidation of NO to NO2was negligible due to the weak reactivity of NO on aerosols, compared to the homogeneous oxidation process. However, the results here reported for the first time that SO2can greatly promote the heterogeneous transformation of NO into NO2and HONO on MgO particles under ambient conditions. The uptake coefficients of NO were increased by 2–3 orders of magnitudes on SO2-aged MgO, compared to the fresh sample. Based on spectroscopic characterization and density functional theory (DFT) calculations, the active sites for the adsorption and oxidation of NO were determined to be sulfates, where an intermediate [SO4–NO] complex was formed during the adsorption. The decomposition of this species led to the formation of NO2and the change of sulfate configuration. The formed NO2could further react with surface sulfite to form HONO and sulfate. The conversion of NO to NO2and HONO on the SO2-aged MgO surface under ambient conditions contributes a new formation pathway of NO2and HONO and could be quite helpful for understanding the source of atmospheric oxidizing capacity as well as the formation of air pollution complexes in polluted regions such as the northern China.

Ag–Mn catalysts with excellent water resistance and ozone decomposition activity were successfully synthesized by simple precipitation and impregnation methods. Under a relative humidity of 65% and space velocity of 840,000 h–1, the 6%Ag/α-Mn2O3-I catalyst showed 99% conversion of 40 ppm O3after 6 h, which was far superior to the performance of the 6%AgMnOx-C (49%), 6%Ag/MnCO3-I (32%), and α-Mn2O3(5%) catalysts. Physicochemical characterization indicated that the chemical state of Ag on the Ag–Mn catalysts determined the O3decomposition activity of the catalysts. The Ag species on the 6%Ag/α-Mn2O3-I catalyst were mainly metallic silver nanoparticles (Agn0), which exhibited much better ozone decomposition performance than the Ag1.8Mn8O16and oxidized silver clusters (Agnδ+) existing on the 6%Ag/MnCO3-I and 6%AgMnOx-C catalysts. The 6%Ag/α-Mn2O3-I catalyst still had above 85% ozone conversion after 60 h under a relative humidity of 65% and space velocity of 840,000 h–1. The slight deactivation of the catalyst was ascribed to the oxidation of Agn0, and its activity could be completely recovered by treatment at 350 °C under an N2atmosphere, which indicated that it is a promising catalyst for ozone decomposition. This research provides guidance for the subsequent development of Ag–Mn catalysts for ozone decomposition with high activity.

ABSTRACTHere, we prepared the novel combined adjuvants, CTB as intra-molecular adjuvant, CpG and aluminum hydroxide (Alum) to strengthen the immunogenicity of clumping factor A221-550of Staphylococcus aureus(S. aureus). The protein-immunoactive results showed CTB-ClfA221-550elicited the strong immune responses to serum from mice immunized with CTB and ClfA221-550, respectively. The mice immunized with CTB-ClfA221-550plus CpG and Alum adjuvant exhibited significantly stronger CD4+T cell responses for IFN-γ, IL-2, IL-4, and IL-17 and displayed the higher proliferation response of splenic lymphocytes than the control groups, in addition, these mice generated the strongest humoral immune response against ClfA221-550among all groups. Our results also showed CTB-ClfA221-550plus CpG and Alum adjuvant obviously increased the survival percentage of the mice challenged by S. aureus. These data suggested that the novel combined adjuvants, CTB, CpG, and Alum, significantly enhance the immune responses triggered with ClfA221-550, and could provide a new approach against infection of S. aureus.AbbreviationsCTB: Cholera Toxin B; CpG: Cytosine preceding Guanosine; ODN: Oligodeoxynucleotides; Alum: Aluminum hydroxide; TRAP: Target of RNAIII-activating Protein; TLR9: Toll-like Receptor 9; TMB: 3, 3ʹ, 5, 5ʹ-tetramethylbenzidine; mAbs: Monoclonal Antibodies; OD: Optical Densities; S. aureus: Staphylococcus aureus; ClfA: Clumping factor A; FnBPA: Fibronection-binding protein A; IsdB: Iron-regulated surface determinant B; SasA: Staphylococcus aureusSurface Protein A; GapC: Glycer-aldehyde-3-phosphate dehydrogenase-C

To clarify how coexisting atmospheric pollutants affect secondary organic aerosol (SOA) formation, we investigated the effects of mixed gaseous pollutants (CO and SO2) and mixed organic–inorganic (MOI) particles on SOA formation during n-butyl vinyl ether (BVE) ozonolysis. Higher CO levels (90 ppm) were found to significantly change the chemical composition of SOA (prompting monomers while reducing oligomer formation) without causing much change in the overall SOA mass. Based on the positive matrix factorization (PMF) analysis, heterogeneous chemical conversions between preformed and newly formed SOA were the major pathways of SOA formation in the presence of MOI particles. Furthermore, MOI particles had an enhancing effect on SOA formation at 1% relative humidity (RH) but a negligible effect at higher RH (10 and 55%). The enhancing effect was attributed to the formation of multifunctional products resulting from high functionalization of preformed and newly formed SOA. The negligible effect observed was ascribed to the cleavage of unstable oligomers as a result of the reversible oligomerization of preformed and newly formed SOA. Even so, MOI particles could still affect the composition of newly formed SOA. These results highlight the need to account for the significant effect of mixed gaseous and particulate pollutants on both SOA constituents and their evolution.

In this study, a series of Ce-OMS-2 catalysts were synthesized by a hydrothermal method, their physicochemical properties and catalytic activity for ozone decomposition were evaluated. The results show that suitable grain size and morphology can be formed as needed by tuning the hydrothermal conditions. In this way, the content of surface oxygen in the catalyst can be increased to enhance the reduction performance of the samples. At the same time, the quantity of low-valent manganese (Mn2+and Mn3+) can be increased to raise the oxygen vacancy concentration, and finally improve the O3elimination performance of the catalyst. On the basis of this study, we screened out a suitable range of hydrothermal conditions, namely 95–100 °C and 8–24 h, which showed a higher ozone conversion rate than manganese oxide catalysts reported to date. The durability of the preferred catalyst under harsh conditions shows that preferred Ce-OMS-2 catalysts can meet the requirements of engineering applications.

Durable Pd-Ce-OMS-2 catalysts for ozone catalytic decomposition under harsh conditions were successfully prepared viaa simple one-step hydrothermal process. The incorporation of Pd could greatly improve the ozone removal performance of the catalysts under high GHSV and RH conditions. The catalysts were evaluated by XRD, ICP-OES, BET, XRF, Raman, TEM, FE-SEM, XAFS, XPS, H2-TPR and O2-TPD. The enhancement effect of Pd is discussed in terms of the relationship between the activity and structure. The inhibiting effect of oxidized palladium on the crystal growth of these catalysts leads to a decrease in the grain size and crystallinity, increasing the proportion of amorphous regions, and thus significantly increases the specific surface area, lattice defects and low-valence manganese content of Ce-OMS-2. The interaction between Pd and Mn enhances the lability of oxygen on the catalyst surface and accelerates the redox reaction. The increase in oxygen vacancy concentration caused by Pd–Mn interactions is the key factor in improving the catalytic ozone decomposition performance of manganese oxide.

The heterogeneous oxidation of sulfur dioxide (SO2) to sulfate on the surface of MgO particles was investigated by in situdiffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT). The in situDRIFTS spectra show that the major products of SO2adsorption on MgO particles are sulfite, bisulfite and sulfate, while the coexisting NO2and O2promote the conversion of sulfite/bisulfite into sulfate. DFT calculations show that the main adsorption products of SO2on the perfect MgO (001) surface, the hydroxylated MgO (001) surface and the step sites of the MgO (001) surface are sulfite (SO2,gas+ Olattice→ SO3,ads), bisulfite and sulfate, respectively. The oxidation of sulfite to sulfate was hardly promoted by the presence of O2at room temperature, because the process needs to overcome an energy barrier of 0.67 eV. The existence of NO2couldn't promote the formation of sulfate, because the direct oxidation of sulfite into sulfate by NO2is difficult (ΔEa= 1.08 eV). However, coexisting NO2with O2can facilitate the oxidation of SO2, which illustrates the micro-mechanism of the synergistic effect between SO2and NO2on MgO. In contrast to sulfite, surface bisulfite formed through the adsorption of SO2on surface OH could be oxidized by O2or NO2viabarrierless processes. This mechanism highlights the synergistic effects of O2/NO2as well as surface hydroxyl on the heterogeneous oxidation of SO2on the MgO surface. Atmospheric implications of the heterogeneous oxidation of SO2on MgO under ambient atmosphere are discussed.

Adsorption is an efficient method for atmospheric NOxabatement under ambient conditions; however, traditional adsorbents suffer from limited adsorption capacity and byproduct formation. Developing a low-cost material with high capacity for atmospheric NO2elimination remains a challenge. Here, we synthesized a nanodispersed Mn3O4/γ-Al2O3(Mn/Al) material that exhibits excellent ability to remove NO2. The 10 wt % Mn/Al sample showed the highest removal capacity, with 247.6 mgNO2/gMn/Al, which is superior to that of activated carbon (42.6 mgNO2/g). There were no byproducts produced when Mn/Al was tested with ppb-level NO2. The NO2abatement mechanism with Mn/Al is different from physisorption or chemisorption. NO2removal is mainly a catalytic process in air, during which surface hydroxyls and lattice oxygen are involved in the oxidation of NO2to nitrate. In contrast, a chemical reaction between Mn3+and NO2is dominant in N2, where Mn3+is converted into Mn4+and NO2is reduced to nitrite. Washing with deionized water is an effective and convenient method for the regeneration of saturated Mn/Al, and an 86% adsorption capacity was recovered after one washing. The results suggest that this low-cost Mn/Al material with easy preparation and regeneration is a promising candidate material for atmospheric NO2elimination.

Manganese oxides are prominent candidates for the catalytic oxidation of volatile organic compounds (VOCs) or ambient decomposition of O3individually. Here, we compared various preparation methods to create a defect-enriched Ag–MnOxnanocomposite that exhibits a remarkably multifunctional activity in VOC combustion and ozone decomposition. Ag+ions were well-dispersed in the microtunnels of Ag–MnOx-H via hydrothermal replacement of the original K+ions; this catalyst’s benzene combustion efficiency (T90%= 216 °C at a space velocity of 90 000 mL h–1g–1) was comparable to that of typical noble metal catalysts. Moreover, the decomposition of ozone over the Ag–MnOx-H catalyst (space velocity = 840 000 mL h–1g–1) under a relative humidity of 60% was above 90%, indicating that it is a promising material for ozone elimination in practical application. The local structure results indicated that silver incorporation via the hydrothermal method facilitates the formation of nonstoichiometric defects in the MnOxmatrix. The large number of active oxygen species related to O vacancies appeared to play critical roles in VOC combustion; moreover, the oxygen vacancies originating from O defects were also critical in O3abatement. This work provides multifunctional catalysts for VOC combustion and ambient O3decomposition and may assist with the rational design of MnOxcatalysts for application in various conditions.

Alkyl vinyl ethers are widely used as fuel additives. Despite this, their atmospheric chemistry and secondary organic aerosol (SOA) formation potentials are still not well-known under complex pollution conditions. In this work, we examined the impact of SO2, relative humidity (RH), and particle acidity on the formation and oxidation state (OSc) of SOA from butyl vinyl ether (BVE) ozonolysis. Increasing SO2concentration produced a notable promotion of SOA formation and OSc due to the significant increase in H2SO4particles and formation of more highly oxidized components. Increased RH in the presence of SO2appeared to promote, suppress, and dominate the formation and OSc of SOA in the dry range (1–10%), low RH range (10–42%), and moderate RH range (42–64%), respectively. This highlights the importance of competition between H2O and SO2in reacting with the stabilized Criegee intermediate in BVE ozonolysis at ambient RH. Increased particle acidity mainly contributed to the change in chemical composition of BVE-dominated SOA but not to SOA formation. The results presented here extend previous analysis of BVE-derived SOA and further aid our understanding of SOA formation potential of BVE ozonolysis under highly complex pollution conditions.

Accurate estimation of terrestrial evapotranspiration (E) is critical to understand the world's energy and water cycles. MOD16 is the core algorithm of the widely used global Edata set (the Moderate Resolution Imaging Spectroradiometer [MODIS] Eproduct). However, it exhibits considerable uncertainties in some regions. Based on the data from 175 flux towers, we identified the key parameters of the MOD16 algorithm using the Sobol’ sensitivity analysis method across biomes. The output of the MOD16 algorithm was sensitive to eight parameters. Among them, β, which is treated as a constant (0.2 kPa) across biomes in the original MOD16 algorithm, was identified as the parameter to which the algorithm was most sensitive. We used the differential‐evolution Markov chain method to obtain the proper posterior distributions for each key parameter across a range of biomes. The values of the key parameters for the different biomes were accurately estimated by differential‐evolution Markov chain in comparison with data from the flux towers. We then evaluated the performances of the original MOD16 and the optimized MOD16 and compared them at multiple spatial scales (i.e., site, catchment, and global). We obtained relatively consistent and more reliable Esimulations using the optimized MOD16 at all three scales. In the future, more attention should be paid to uncertainties in the algorithm's structure and its parameterizations of soil moisture constraint, canopy resistance, and energy partitioning. We evaluated the MOD16 algorithm based on data from 175 flux towersWe acquired optimized parameters for the MOD16 algorithm via the DE‐MC schemeWe evaluated and compared the results at multiple temporal and spatial scales

Introduction. The development of combinatorial adjuvants is a promising strategy to boost vaccination efficiency. Accumulating evidence indicates that manganese exerts strong immunocompetence and will become an enormous potential adjuvant. Here, we described a novel combination of Mn2+ plus aluminum hydroxide (AH) adjuvant that significantly exhibited the synergistic immune effect. Methodology. Initially, IsdB3 proteins as the immune-dominant fragment of IsdB proteins derived from Staphylococcus aureus (S. aureus) were prepared. IsdB3 proteins were identified by western blotting. Furthermore, we immunized C57/B6 mice with IsdB3 proteins plus Mn2+ and AH adjuvant. After the second immunization, the proliferation of lymphocytes was measured by the cell counting kit-8 (CCK-8) and the level of IFN-γ, IL-4, IL-10, and IL-17 cytokine from spleen lymphocytes in mice and generation of the antibodies against IsdB3 in serum was detected with ELISA, and the protective immune response was assessed through S. aureus challenge. Results. IsdB3 proteins plus Mn2+ and AH obviously stimulated the proliferation of spleen lymphocytes and increased the secretion of IFN-γ, IL-4, IL-10, and IL-17 cytokine in mice, markedly enhanced the generation of the antibodies against IsdB3 in serum, observably decreased bacterial load in organs, and greatly improved the survival rate of mice. Conclusion. These data showed that the combination of Mn2+ and AH significantly acted a synergistic effect, reinforced the immunogenicity of IsdB3, and offered a new strategy to increase vaccine efficiency.

Photothermal catalysis is extremely promising for the removal of various indoor pollutants owing to its photothermal synergistic effect, while the low light utilization efficiency and unclear catalytic synergistic mechanism hinder its practical applications. Here, nitrogen atoms are introduced, and Pt nanoparticles are loaded on TiO2to construct Pt/N-TiO2-H2, which exhibits 3.5-fold higher toluene conversion rate than the pure TiO2. Compared to both photocatalytic and thermocatalytic processes, Pt/N-TiO2-H2exhibited remarkable performance and stability in the photothermocatalytic oxidation of toluene, achieving 98.4% conversion and 98.3% CO2yield under a light intensity of 260 mW cm–2. Furthermore, Pt/N-TiO2-H2demonstrated potential practical applicability in the photothermocatalytic elimination of various indoor volatile organic compounds. The synergistic effect occurs as thermocatalysis accelerates the accumulation of carboxylate species and the degradation of aldehyde species, while photocatalysis promotes the generation of aldehyde species and the consumption of carboxylate species. This ultimately enhances the photothermocatalytic process. The photothermal synergistic effect involves the specific conversion of intermediates through the interplay of light and heat, providing novel insights for the design of photothermocatalytic materials and the understanding of photothermal mechanisms.

In this study, a wall-coated flow tube reactor, in situdiffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC) were used to investigate the effect of water on the heterogeneous reactions of SO2and NH3on the surfaces of α-Fe2O3and γ-Al2O3. Flow tube results show that water exhibited little effect on the initial uptake coefficients (γBET) of SO2but the addition of NH3increased the γBETat various relative humidity (RH) values on both α-Fe2O3and γ-Al2O3. The γBETof SO2in the presence of NH3was negatively RH dependent on α-Fe2O3, which decreased from (8.80 ± 2.30) × 10−6at 9% RH to (2.24 ± 0.71) × 10−6at 85% RH. In contrast, the γBETof SO2in the presence of NH3on γ-Al2O3increased from (1.32 ± 0.45) × 10−6at 10% RH to (2.56 ± 0.39) × 10−6at 74% RH. Surface product analysis by DRIFTS and IC shows that ammonium sulfate-like species formed, whereas the variation of SO42−and NH4+with RH differed on Fe2O3and Al2O3. With the increase of RH, sulfate tended to transform into bisulfate on Fe2O3with copresence of NH3, whereas surface-coordinated sulfite transformed to water-solvated sulfite and water-solvated sulfate species on Al2O3regardless of the presence of NH3. During this process, the amount of sulfate decreased with RH on Fe2O3, as opposed to that on Al2O3; yet the NH4+was inhibited to form by adsorbed water on both surfaces. The different interaction mechanisms among water, NH3, and SO2on Fe2O3and Al2O3as well as the atmospheric implications have been proposed.

Although the heterogeneous conversion of SO2on TiO2has been considered a potential source of sulfate in the troposphere, little is known about the kinetics of SO2uptake on TiO2under ambient conditions. In this study, heterogeneous reactions of SO2on a TiO2surface at 298 K were investigated by a coated-wall flow tube reactor and in situ diffuse reflectance Fourier transformed infrared spectroscopy (DRIFTS). The effect of UV irradiation, relative humidity (RH), and O2on the uptake coefficients and adsorption amount of SO2have been analyzed comprehensively. UV irradiation exhibits a slight effect on the initial uptake coefficient (γBET), which increases from 1.23 × 10–6to 1.48 × 10–6in air conditions and 5.89 × 10–7to 6.42 × 10–7in a N2stream under dry conditions. Surface water exhibits a competition effect on the adsorption of SO2on TiO2. An increase in RH (in the range of 0–75%) led to a decrease in the γBETand adsorption amount of SO2both in the dark and the light reaction. In contrast, oxygen plays an important role in the uptake of SO2. Both the uptake coefficients and adsorption amount of SO2on TiO2decreased in the N2stream compared to those in air conditions. Only sulfite was formed during the adsorption of SO2in dark and dry conditions. The presence of UV irradiation was found to promote the conversion of SO2to sulfate and the adsorption amount of sulfur species on the TiO2surface. These results suggest that heterogeneous reaction on TiO2as a sink for SO2is not important in the atmosphere.

Transition metal (cerium and cobalt) doped γ-MnO2(M-γ-MnO2, where M represents Ce, Co) catalysts were successfully synthesized and characterized. Cerium-doped γ-MnO2materials showed ozone (O3) conversion of 96% for 40 ppm of O3under relative humidity (RH) of 65% and space velocity of 840 L g–1h–1after 6 h at room temperature, which is far superior to the performance of the Co-γ-MnO2(55%) and γ-MnO2(38%) catalysts. Under space velocity of 840 L g–1h–1, the conversion of ozone over the Ce-γ-MnO2catalyst under RH = 65% and dry conditions within 96 h was 60% and 100%, respectively, indicating that it is a promising material for ozone decomposition. XRD and HRTEM data suggested that Ce-γ-MnO2formed mixed crystals consisting of α-MnO2and γ-MnO2with specific surface area increased from 74 m2/g to 120 m2/g compared to undoped γ-MnO2, thus more surface defects were introduced. H2-TPR, O2-TPD, XPS, Raman, and EXAFS confirmed that Ce-γ-MnO2exhibited more surface oxygen vacancies and surface defects, which play a key role during the decomposition of ozone. This study provides important insights for developing improved catalysts for gaseous ozone decomposition and promoting the performance of manganese oxide for practical ozone elimination.

In this study, Ag supported on TiO2, SiO2, and SiO2–TiO2catalysts were prepared through the impregnation method and their performance for the selective catalytic oxidation of ammonia (NH3–SCO) was tested. The results showed that the Ag/SiO2–TiO2(denoted as Ag/Si–Ti) performed at a much higher activity than Ag/TiO2and Ag/SiO2at low temperature range. Characterization results revealed that SiO2possessed a high surface area, but lacked OH groups and acidic sites; TiO2possessed abundant OH groups and acidic sites, but the surface area was low. High surface area and abundant OH groups were a benefit for the dispersion of Ag, and acidic sites contributed to the adsorption and activation of ammonia. The synergistic effect compromised the advantages and disadvantages of SiO2and TiO2, which improved the dispersion of Ag, enriched acidic sites of the catalyst and maintained Ag0content at an appropriate level, therefore enhanced the NH3–SCO activity of Ag/Si–Ti catalyst.

In this work, a relationship between the role of NH3and the properties of mineral oxides (α-Fe2O3, α-Al2O3, CaO, and MgO) in the evolution of NO3–, SO42–, and NH4+has been established. It was found that the promotion effect of NH3was more favorable for the formation of NO3–(or SO42–) and NH4+on acidic α-Fe2O3and α-Al2O3due to acid–base interactions between NO2with NH3or between SO2and NH3, while this effect was weaker on basic CaO and MgO possibly due to their basic nature. The acid–base interaction (NO2/SO2with NH3) overpowered the redox reaction (SO2with NO2) on Fe2O3owing to its unique redox chemistry. However, the opposite was found on basic CaO and MgO for the formation of SO42–and NO3–. Under equivalent concentration conditions, the two synergistic effects did not further strengthen on Fe2O3, CaO and MgO due to a competition effect. In NH3-rich situation, a synchronous increase of SO42–, NO3–, and NH4+occurred on Fe2O3. On acidic Al2O3, the favorable adsorption of NH3on the surface as well as the existence of NO2with an oxidizing capability synergistically promoted the formation of SO42–, NO3–, and NH4+.

MFI zeolites (ZSM-5) with different Si/Al ratios were synthesized to assess their adsorptive removal of dichloromethane vapor, compared with FAU zeolites (NaX and NaY). All adsorbents were characterized by means of N2adsorption, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The adsorption and desorption performance, water vapor tolerance, and regeneration ability were fully examined. FAU zeolites exhibited better equilibrium capacity than MFI zeolites, while MFI zeolites had superior dynamic capacity. The kinetic uptake of FAU zeolites was significantly depressed by low humidity levels in the mixture. Regardless of the type of zeolite, high Si content was not only beneficial to equilibrium adsorption but also helpful for water vapor resistance. ZSM-5 (200) (SiO2/Al2O3= 200) with the highest Si/Al ratio was the best candidate in this study for removal of dichloromethane. In addition, it could be reused without a significant decrease in uptake after several regeneration cycles. With the aid of in situ diffuse reflectance Fourier transform infrared spectroscopy and density functional theory simulation, adsorbed dichloromethane was found to be in intimate contact with the pore window of FAU zeolites but was surrounded by the pore walls of MFI zeolites. Experimental and theoretical results were consistent with each other and indicated that MFI zeolites show better adsorptive selectivity of dichloromethane (DCM) over water than FAU.

Precipitation chemistry analysis is essential to evaluate the atmospheric environmental quality and identify the sources of atmospheric pollutants. In this study, we collected a total of 480 precipitation samples at 6 sampling sites in the northern and southern slopes of Wushaoling Mountain from May 2013 to July 2014 to analyze the chemical characteristics of precipitation and to identify the main sources of ions in precipitation. Furthermore, we also explored the indicative significance for sand dust events in the northern and southern slopes of Wushaoling Mountain based on the precipitation chemistry analysis. During the sampling period (from May 2013 to July 2014), the pH values, EC (electrical conductivity) values and concentrations of cations (Ca2+, Mg2+, Na+, K+and NH4+) and anions (SO42–, NO3–, Cl–, NO2–and F–) in precipitation were different in the northern and southern slopes at daily and seasonal time scales, with most of the values being higher in the northern slope than in the southern slope. The chemical type of precipitation in the southern and northern slopes was the same, i.e., SO42–-Ca2+-NO3–-Na+. The concentrations of ions in precipitation were mainly controlled by terrigenous material and anthropogenic activities (with an exception of Cl–). The concentration of Cl–in precipitation was mainly controlled by the sea salt fraction. The concentrations of Na+and Cl–showed an increasing trend after the occurrence of sand dust events both in the northern and southern slopes. In addition, after the occurrence of sand dust events, the concentrations of K+, Mg2+, SO42–, NO3–and Ca2+showed an increasing trend in the southern slope and a decreasing trend in the northern slope. It is our hope that the results may be helpful to further understand the atmospheric pollution caused by sand dust events in the Wushaoling Mountain and can also provide a scientific basis for the effective prevention of atmospheric pollution.

Global and regional estimates of daily evapotranspiration are essential to our understanding of the hydrologic cycle and climate change. In this study, we selected the radiation‐based Priestly‐Taylor Jet Propulsion Laboratory (PT‐JPL) model and assessed it at a daily time scale by using 44 flux towers. These towers distributed in a wide range of ecological systems: croplands, deciduous broadleaf forest, evergreen broadleaf forest, evergreen needleleaf forest, grasslands, mixed forests, savannas, and shrublands. A regional land surface evapotranspiration model with a relatively simple structure, the PT‐JPL model largely uses ecophysiologically‐based formulation and parameters to relate potential evapotranspiration to actual evapotranspiration. The results using the original model indicate that the model always overestimates evapotranspiration in arid regions. This likely results from the misrepresentation of water limitation and energy partition in the model. By analyzing physiological processes and determining the sensitive parameters, we identified a series of parameter sets that can increase model performance. The model with optimized parameters showed better performance (R2= 0.2–0.87; Nash‐Sutcliffe efficiency (NSE) = 0.1–0.87) at each site than the original model (R2= 0.19–0.87; NSE = −12.14–0.85). The results of the optimization indicated that the parameter β(water control of soil evaporation) was much lower in arid regions than in relatively humid regions. Furthermore, the optimized value of parameter m1(plant control of canopy transpiration) was mostly between 1 to 1.3, slightly lower than the original value. Also, the optimized parameter Toptcorrelated well to the actual environmental temperature at each site. We suggest that using optimized parameters with the PT‐JPL model could provide an efficient way to improve the model performance. To identify the key parameters of the PT‐JPL model specific to different biomes by using SA with forcing dataTo optimize the selected key parameters using the DEMC scheme for different biomesTo evaluate and compare the performance of the original model and the optimized model across different biomes

The role of hydroxyl groups (OH) is significant in understanding the surface reactions on oxides. Here we combined spectroscopic experiments and theoretical calculations to reveal the role of OH in the heterogeneous reactions of NO2on TiO2nanoparticles with various crystal structures. The interaction between OH and NO2was determined to be a critical step, giving rise to the formation of surface HNO3. HNO3was found to be either a stable product on amorphous TiO2, or an important intermediate of nitrate on anatase due to its further reaction with nearby OH. The lack of surface OH on rutile limited its reactivity toward NO2. This study presents clear evidence that the reactivity of TiO2toward NO2greatly depends on the surface OH as well as the crystalline form. Considering the ubiquitous presence of TiO2nanoparticles in catalysts and in natural environments, our results could provide insights helpful to future research in both environmental catalysis and atmospheric chemistry.

The distribution of stable isotopes and ions in precipitation in the Shule River Basin, northwestern China, were investigated to understand the regional water cycle and precipitation input to groundwater recharge. The study found that the mean annual concentrations of Ca2+, Na+, SO42–, Cl–, Mg2+, NO3–, and K+in the basin were lower than those in other arid areas of northwestern China. The average concentrations of ions in the lower reaches of the Shule River were higher than those in the upper reaches. The results showed that the main ionic concentrations decreased with the increase of precipitation amount, indicating that heavy precipitation cannot only wash crustal aerosols out of the atmosphere, but also create a dilution effect. Cl–and Na+in precipitation had a strong and positive correlation, suggesting a common origin for the two ions. However, the excess of Na+, combined with non-marine SO42–and NO3–, indicated that some ions were contributed by terrestrial origins. In the extremely arid regions of northwestern China, the evaporation process obviously changes the original relationship between δ2H and δ18O in precipitation, and leads to dexcess values <8‰. δ18O and temperature were significantly correlated, suggested that temperature strongly affected the characteristics of isotopes in the study area. The δ18O value indicates a dominant effect of westerly air masses and southwest monsoon in warm months, and the integrated influence of westerly and Siberian-Mongolian polar air masses in cold months. The d-excess values were generally lower in warm months than those in cold months, indicating that post-condensation processes played a significant role in the water cycle. The results provide reliable precipitation input information that can be used in future groundwater recharge calculations in the study area.

Fluorinated amino acids are a class of highly valuable building blocks that are widely employed in biological science and pharmaceutical industry for improved stability, activity, and folding property of proteins. However, the synthetic approach has conventionally been constrained by harsh conditions and limited substrate range. We demonstrate a general synthetic protocol for photoinduced α-CF3amino acids using continuous flow technology that benefits from enhanced fusion and precise control of reaction time, making it potentially useful in large-scale peptide synthesis.

Manganese oxides are one of the most promising candidates for ambient decomposition of O3. However, catalysts with high efficiency require complicated preparation processes to cultivate active microstructures. This study developed a simple and easy to scale up method to produce catalysts via thermal annealing of Mn precursor. With slight addition of Ce and Pd, the obtained PdCe–MnOxcatalyst exhibited excellent O3removal activity in the presence of water vapor. Numerous characterization methods, including X-ray diffraction, high-resolution transmission electron microscopy, mapping, Brunauer–Emmett–Teller, H2-temperature-programmed reduction, O2-temperature-programmed desorption, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy, were applied to explore the relationship between activity and structure. The slight addition of Pd and Ce not only boosts the formation of surface vacancy species but also enhances the water vapor resistance, all of which contribute to its excellent ozone decomposition performance.

The effects of Mn2+precursors on the structure and ozone decomposition activity of cryptomelane-type manganese oxide (OMS-2) catalysts were investigated under high-humidity conditions. The OMS-2 catalysts were synthesized using a hydrothermal approach. Characterization of OMS-2 was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), N2physical adsorption, Raman spectroscopy, X-ray absorption fine structure (XAFS), H2temperature-programmed reduction (H2-TPR), and inductively coupled plasma (ICP) spectroscopy. The OMS-2-Ac synthesized using MnAc2as a Mn2+precursor showed the best catalytic activity for ozone decomposition (∼80%) under RH = 90% and space velocity of 600000 h–1and is a promising catalyst for purifying waste gases containing ozone under high-humidity conditions. Acetate groups could prevent the aggregation of manganese oxide particles, which may introduce more crystalline defects. On the basis of the characterization results, it is supposed that the greater surface area and higher amount of Mn3+are the main factors that contribute to the excellent performance of OMS-2-Ac. This study can improve our understanding of ozone decomposition on OMS-2 catalysts and serve as a guide in using OMS-2 for ozone removal.

To investigate the sensitivity of secondary aerosol formation and oxidation capacity to NOxin homogeneous and heterogeneous reactions, a series of irradiated toluene/NOx/air and α-pinene/NOx/air experiments were conducted in smog chambers in the absence or presence of Al2O3seed particles. Various concentrations of NOxand volatile organic compounds (VOCs) were designed to simulate secondary aerosol formation under different scenarios for NOx. Under “VOC-limited” conditions, the increasing NOxconcentration suppressed secondary aerosol formation, while the increasing toluene concentration not only contributed to the increase in secondary aerosol formation, but also led to the elevated oxidation degree for the organic aerosol. Sulfate formation was suppressed with the increasing NOxdue to a decreased oxidation capacity of the photooxidation system. Secondary organic aerosol (SOA) formation also decreased with the presence of high concentration of NOx, because organoperoxy radicals (RO2) react with NOxinstead of with peroxy radicals (RO2or HO2), resulting in the formation of volatile organic products. The increasing concentration of NOxenhanced the formation of sulfate, nitrate and SOA under “NOx-limited” conditions, in which the heterogeneous reactions played an important role. In the presence of Al2O3seed particles, a synergetic promoting effect of mineral dust and NOxon secondary aerosol formation in heterogeneous reactions was observed in the photooxidation. This synergetic effect strengthened the positive relationship between NOxand secondary aerosol formation under “NOx-limited” conditions but weakened or even overturned the negative relationship between NOxand secondary aerosol formation under “VOC-limited” conditions. Sensitivity of secondary aerosol formation to NOxseemed different in homogeneous and heterogeneous reactions, and should be both taken into account in the sensitivity study. The sensitivity of secondary aerosol formation to NOxwas further investigated under “winter-like” and NH3-rich conditions. No obvious difference for the sensitivity of secondary aerosol formation except nitrate to NOxwas observed.

Oxygen-deficient TiO2was prepared with a low-temperature method and utilized in photocatalytic removal of gaseous NO at the 400 ppbv level in air under visible light (420 nm < λ < 700 nm) irradiation. Catalysts synthesized at 200 °C (TiO2-200) exhibited the highest ability to remove the NO gas in air under visible light irradiation. A higher oxidation ability for NO2to NO3–leads to a higher conversion of NOxon TiO2-200. The relationship between the physicochemical properties and the photocatalytic performance of the as-prepared catalyst is discussed. The large surface area of TiO2-200 can provide more active sites for the reaction. The oxygen vacancies of TiO2-200 can effectively expand the absorption of visible light and accelerate the separation of photogenerated electrons and holes. The first-principles density functional theory (DFT) calculation further confirms the role of oxygen vacancies on the narrowing of the band gap and separating of photogenerated electron–hole pairs.

Smog chamber experimental systems, which have been widely used in laboratory simulation for studying atmospheric processes, are comprehensively reviewed in this paper. The components, development history, main research topics and main achievements of smog chambers are introduced. Typical smog chambers in the world, including their volumes, wall materials, light sources and features, are summarized and compared. Key factors of smog chambers and their influences on the simulation of the atmospheric environment are discussed, including wall loss, wall emission and background pollutants. The features of next-generation smog chambers and their application prospect in future studies of the atmospheric environment are also outlined in this paper.This review summarizes the key features of smog chambers and their application in atmospheric process studies, bringing new insights into development directions for next-generation smog chambers.

Abstract: The amount and timing of aquifer recharge and the evolution of lakes and groundwater in the south-eastern Badain Jaran desert of Inner Mongolia, with high megadunes, has been investigated using stable isotopes and hydrochemistry. Unsaturated zone moisture profiles down to 22 m have recorded recharge over 1185 years. Small but finite amounts of recharge are recorded with mean recharge rates of 0.95-1.33 mm year−1, determined using a chloride mass balance technique. The unsaturated profile also acts as a unique archive of hydrological and climate change. Before 1300, it was relatively dry but distinct wet periods may be recognised during 1340-1450, 1500-1610 and 1710-1820. Since the mid 1800s, the climate shows a trend towards greater aridity. The interdune lakes are generally fresh but locally, hypersaline lakes are found in juxtaposition. This implies that in general, the lakes have low residence times and flow back into the dune system, but sedimentary obstruction locally prevents outflow and extreme evaporation occurs. The stable isotope records show that the lakes are fed by palaeowaters which on the basis of other proxy data must predate the Last Glacial Maximum. Their recharge source is problematic but most likely this derives from a diminishing water table extending some 30 m south to the Yabulai Mountains.

The Co3O4spinel is one of the most promising transition metal oxide (TMO) catalysts for volatile organic compound (VOC) treatment. Substituting effects have usually been utilized to improve the catalytic performance of the Co3O4spinel. In this study, Cu- and Ni-substituted Co3O4catalysts derived from mixed metal–organic frameworks (MMOFs) retained similar spinel structures but exhibited improved and reduced performance for o-xylene oxidation, respectively. Physicochemical characterization and DFT calculations revealed that Cu and Ni substitution into the Co3O4spinel varied the valence (Co3+/Co2+) and geometry (CoOh/CoTd) distributions of Co cations through different partial electron transfer and substitution sites. The higher Co3+/Co2+and CoOh/CoTdratios of the CuCo2O4catalyst contributed to the superior reducibility and oxygen mobility, which facilitated the oxidation of intermediates at lower temperatures in the catalytic oxidation of o-xylene. Meanwhile, the NiCo2O4catalyst with lower Co3+/Co2+and CoOh/CoTdratios could not completely oxidize intermediates under the same conditions due to inferior redox properties. Therefore, the CuCo2O4catalyst showed superior catalytic activity and stability to the NiCo2O4catalyst for the catalytic oxidation of o-xylene. This work provides insights into the synthesis of substituted Co3O4catalysts from MMOFs and mechanism of substituting effects, which might guide the design of efficient TMO catalysts for VOC treatment.

Pt/Al2O3catalysts showing excellent activity and stability have been used in various reactions, including HCHO oxidation. Herein, we prepared Pt–Na/Al2O3catalysts with a Pt content of 0.05 wt % to reveal the key factors determining the anchoring of Pt as well as the catalytic activity and mechanism of HCHO oxidation. Pt–Na/nano-Al2O3(denoted as Pt–Na/nAl2O3) catalysts with 0.05 wt % Pt content could completely oxidize HCHO to CO2at room temperature, which is the lowest Pt content used in HCHO catalytic oxidation to our knowledge. After Na addition, terminal hydroxyl groups (denoted as HO-μter) on nano-Al2O3were transformed to doubly bridging hydroxyl groups between Na and Al (denoted as HO-μbri(Na–Al)), which atomically dispersed Pt species. Pt anchoring further promoted the regeneration of HO-μbri(Na–Al)by activating O2and H2O, oxidizing HCHO to CO2directly by the fast reaction step ([HCOO–] + [OH]a→ CO2+ H2O). Our study revealed that the HO-μbri(Na–Al)synergistically generated by HO-μterand Na species provided anchoring sites for Pt species.

The miscellaneous volatile organic compounds (VOCs) in industrial flue gas streams usually demonstrate significant mutual inhibition effects, and the behavior of a particular VOC in mixtures is not clear, which hinders the application of catalytic technology. This study examines the catalytic oxidation and mixing effects of representative VOCs in industrial exhausts, consisting of acetone (AC), ethyl acetate (EA), and toluene (Tol), on common Mn-based catalysts (e.g., MnO2, Mn2O3, LaMnO3, and Mn3O4) by means of intrinsic activity evaluation, coadsorption, VOC temperature-programmed oxidation, in situ diffuse reflectance infrared Fourier transform spectroscopy, and gas chromatography–mass spectrometry. The results showed no inhibiting effect on the conversion of these VOCs when combusted together; instead, a significant mutual promotion effect was found, especially on Tol destruction, with a sharp decrease in the Tol T50from 214 to 158 °C on MnO2. It is proposed for the first time that the addition of AC/EA in Tol combustion leads to the generation of o/m-methyl phenol, which changes the rate-determining step of the ring-opening process, thus elevating the conversion of Tol together with AC and EA in the mixture at low temperatures.