Synergistic Reaction Research Articles

A thiol-containing zirconium MOF functionalized with silver nanoparticles for synergistic CO2 cycloaddition reactions.

Thiol-containing biomolecules, such as cysteine and glutathione, play essential roles in regulating the polarity and reactivity of the systems. Among functional MOFs, thiol MOFs, a subclass with a thiol group-containing ligand, are relatively less explored due to their synthetic challenges and stability and storage issues. Despite these drawbacks, they have many advantages due to the electronically soft thiol groups with strong reactivity and affinity toward soft metal ions. Herein, we have taken advantage of the affinity between thiol groups and a soft metal (Ag) by functionalizing a thiol MOF with Ag ions and finally synthesizing a silver nanoparticle-functionalized heterogeneous catalyst (Ag@Zr-DMBD). The Zr,Ag centre of the thiol MOF catalyst acts as an active centre and synergistically binds with the electron-rich oxygen atom of a terminal epoxide for efficient CO2 fixation to the corresponding cyclic carbonates under atmospheric CO2 pressure in 8 h. Finally, a rationalized reaction mechanism is proposed based on literature reports and current results. This work presents a viable strategy for using thiol MOFs as heterogeneous catalysts for CO2 fixation under mild conditions.

Synergistically enhanced K–Se and K–Sn storage reaction in multidimensional carbon structure

K–Sn and K–Se batteries are expected to simultaneously realize synergistic reactions in a single electrode with high capacity and stability of energy storage performance. However, the difficulty of these reactions is realizing the stable storage of K–Sn and the redox reaction of Se in the electrode simultaneously. Therefore, it is expected to design a new electrode structure to solve the above problems. Herein, a multidimensional structure of SnSe is designed with enhanced performance. In this structure, SnSe nanoparticles are co-encapsulated by “inner” 3D graphene aerogel and “outer” nitrogen doped carbon (SnSe/3D RGO@NC). The “outer” nitrogen doped carbon could provide stronger reaction product adsorption affinity as well as improve the potassium energy storage. The “inner” and “outer” carbon materials could synergistically improve the electrical conductivity, promoting the redox kinetics of Se to achieve K–Se energy storage. Ex-situ test results indicate K–Sn reaction and the redox reaction of Se were formed in the electrode. Finally, this electrode provides excellent potassium storage reversibility (312 mAh·g−1 after 350 cycles with 0.016% capacity fading per cycle) and favorable rate (196 mAh·g−1 at 5 A g−1) with K–Sn and K–Se reaction process. This study could provide ideas for structural design to utilize synergistic reactions with enhanced electrochemical performance in individual battery system.

S-scheme MIL-101(Fe) octahedrons modified Bi2WO6 microspheres for photocatalytic decontamination of Cr(VI) and tetracycline hydrochloride: Synergistic insights, reaction pathways, and toxicity analysis

Solar-driven elimination of refractory contaminants is an ideal route to tackle the environmental issues. Nevertheless, the photocatalytic performance of photocatalysts is heavily restrained due to the insufficient accessible reactive sites and fast electrons/holes reunion. Herein, a novel metal–organic framework-based S-scheme heterostructure of MIL-101(Fe)/Bi2WO6 was synthesized by a simple solvothermal approach. The optimized MIL-101(Fe)/Bi2WO6 (MIL/BWO-2) affords the highest photo-activities under visible light, which are 13.7, 6.7 folds greater for Cr(VI) reduction, and 0.8, 10.5 folds higher for tetracycline hydrochloride oxidation compared with individual Bi2WO6 and MIL-101(Fe), respectively. The preeminent catalytic capability lies in two aspects: 1) the introduction of MIL-101(Fe) substantially enlarges the surface area of the composites, offering ample reaction sites and fostering pollutant adsorption and mass transportation; 2) the novel S-scheme photo-carrier transport mechanism assisted by oxygen vacancies favors spatial segregation and transport of photoinduced electrons/holes with superior redox capacity. Reactive species identification experiments verify that O2– and e– dominantly contribute to Cr(VI) reduction, while O2–, h+ and OH account for tetracycline hydrochloride destruction. Furthermore, the tetracycline photo-decomposition pathway, eco-toxicity evaluation, and photocatalytic mechanism were investigated comprehensively. This research paves the way for building high-performance MOFs-based S-scheme heterojunctions toward photocatalytic water purification.

In-situ synthesis and assembly of nanospheres (Py1H2PW, Py2H1PW, and Py3PW) in wood to promote flame retardation

Hybrid wood is a composite with the advantages of both wood and inorganic material. Here, a novel hybrid wood was fabricated from wood and nanospheres by the in-situ assembly of phosphotungstic acid (HPW) and pyridine (PY) at room temperature. The uniformly distributed amphiphilic PY-PW nanospheres provided controllable particle size and acid properties by changing the HPW-PY molar. Examination under Scanning electron microscopy (SEM) showed the presence of a uniform nanosphere coating by the nanospheres, and FE-SEM/EDS showed even distribution on the cell walls. The successful synthesis of the nanospheres in the wood was confirmed by Transmission electron microscopy (TEM). The PY-PW/wood hybrid was also resistant to leaching, attributed to the amphiphilicity of the nanospheres. The hybrid wood also showed superior flame retardation, with a UL-94 V-0 rating, and significantly reduced the peak heat release rate (pk-HRR) and total smoke release (TSR) values of the untreated wood by 44.7 % and 51.7 %, respectively. The enhanced flame retardation was attributed to synergistic effects and catalytic carbon reactions resulting from high-density nitrogen/phosphorus/oxygen cross-linking in the carbon layer in the condensed phase and the removal of combustible gases by free radicals. This hybrid wood material has potential application for the development of fire-safe wood.

Construction of nanosized MoP decorated highly crystalline carbon nitride sphere as an excellent photocatalyst for boosted photocatalytic hydrogen production

High-crystalline carbon nitride (HCCN) is recognized as a promising semiconductor photocatalyst in alleviating the energy crisis and protecting the environment in the current field of photocatalysis. However, the ordinary crystalline carbon nitride is generally morphologically irregular with few surfactant sites, which limits its further application. In this work, we successfully constructed spherical HCCN embedded with MoP nanoparticles as a co-catalyst by a simple calcination treatment to form a stable and efficient MoP-HCCN composite photocatalyst. As expected, as-prepared MoP-HCCN composites presented superior photocatalytic activities for water splitting into H 2 production, and the optimal 5 wt.% MoP-HCCN exhibited the optimum photocatalytic hydrogen production rate up to 10594.29 μmol·g -1 ·h -1 with the corresponding AQE reached 7.2%, which is 3.4 times than pristine HCCN and 109.9 times than amorphous carbon nitride (ACN), respectively. The significant promotion in photocatalytic property is mainly due to the synergistic reaction between MoP and HCCN for effectively enhancing the segregation and rapid transportation of photogenerated electron-hole pairs. Finally, the feasible photocatalysis mechanism of MoP-HCCN compound photocatalyst is inferred. This work presents a promising design idea for developing efficient HCCN-based composite photocatalytic for hydrogen production.

Tailoring Rational Crystal Orientation and Tunable Sulfur Vacancy on Metal‐Sulfides toward Advanced Ultrafast Ion‐Storage Capability

AbstractAttracted by high energy density and power density, metal‐sulfides anodes have promising application prospects in fast charging batteries. However, they still suffer from low electrical conductivity and sluggish electrochemical kinetics, resulting in poor fast charging capacity. Herein, spindle‐like antimony sulfide (Sb2S3) is rationally tailored with favorable (hk1) crystal orientation and rich S‐vacancies using a simple hydrothermal method, which improve electric conductivity significantly. Triggered by S‐vacancies lattice defects, SbOC interfacial bonds and S‐doped carbon layer are built successfully. Under their multiple‐controlling synergistic effects, electrochemical kinetics and reaction reversibility are promoted effectively. As expected, Sb2S3/HTAB@C show high average initial coulombic efficiency of 86.12%, and deliver 624.5 and 428.4 mAh g−1 after cycling 100 cycles at 10.0 and 30.0 A g−1 respectively in Li‐ion batteries (LIBs). Electrochemical kinetic analysis and theoretical calculations indicate that superior ultrafast charging capacity originates from quickened interfacial electron/ions transferring and alleviates electrochemical polarization. Ex situ technologies powerfully prove good stability of (hk1) orientation, SbOC bonds and S‐doped carbon layer. Notably, full LIBs of SS/H@C versus LiFePO4@C display 500.9 and 398.3 mAh g−1 at 5.0 and 10.0 A g−1, respectively. This study is anticipated to open avenue to develop advanced metal‐sulfides anodes for fast charging batteries.

Synergistic removal of NO and Hg0 over Co-Mn/TiO2 catalyst: High efficiency and in-depth reaction mechanism

The key challenge for controlling Hg0 using selective catalytic reduction (SCR) technology is to develop a suitable catalyst capable of operating in a cost-effective manner, so it is necessary to study the in-depth reaction mechanism. Herein, Co-Mn/TiO2 catalysts were fabricated by sol-gel method, excellent stability and high efficiency of Hg0 removal (100%) and NO conversion (99%) are concurrently reached at 180 °C, which are benefited from the abundant active oxygen species on the catalysts. In order to clarify the synergistic reaction process, the mechanism of mutual effects between SCR atmosphere and Hg0 is highly dedicated. Specifically, NO and O2 were beneficial to Hg0 oxidation, while NH3 competitive adsorption with Hg0 and consumption of active oxygen species prevent the Hg0 oxidation. Impressively, the inhibition effect of NH3 was not weakened but also intensified, mainly due to the co-existence of NO and NH3 could induce partial HgO reduction. What's more, the direct evidence for the synergistic reaction mechanism of NO and Hg0 is hypothesized by a combination of XPS and in-situ DRIFTs. These findings thus open up a way to address the simultaneous removal of NO and Hg0 in industry.

Dual Pt-Ni atoms dispersed on N-doped carbon nanostructure with novel (NiPt)-N4C2 configurations for synergistic electrocatalytic hydrogen evolution reaction

Single-atom catalysts with high atomic utilization efficiency, well-defined active centers, and catalytic sites with low atomic coordination numbers are promising to boost electrocatalytic performance. Dual-atom catalysts (DACs) with neighboring heteroatoms are expected to exert the synergistic effect of the two atoms, further improving the activity. Herein, we report a PtNi-NC catalyst consisting of PtNi dual atoms anchored on a nitrogen-doped carbon substrate synthesized through atomic layer deposition. X-ray absorption spectroscopy confirms the existence of the PtNi dual atoms. The as-prepared PtNi-NC catalyst exhibits extraordinary catalytic activity, with an overpotential of 30 mV for hydrogen evolution reaction (HER) in acidic media at a current density of 10 mA cm−2, which is comparable to that of commercial 20 wt% Pt/C. Notably, PtNi-NC possesses a much higher mass activity, about 21 times, than 20 wt% Pt/C. Density functional theory calculations reveal that PtNi dual atoms generate a synergistic effect by modulating the local electronic structure and optimizing the charge distribution, contributing to optimized adsorption properties and enhanced electrocatalytic performance. This work provides a new avenue for the fabrication of DACs, revealing their potential applications in electrocatalytic HER and beyond.

Rapid Biotransformation of Luminescent Bimetallic Nanoparticles in Hepatic Sinusoids.

Liver sequestration, mainly resulting from the phagocytosis of mononuclear phagocyte system (MPS) cells, is a long-standing barrier in nanoparticle delivery, which severely decreases the disease-targeting ability, leads to nanotoxicity, and inhibits clinical translation. To avoid long-term liver sequestration, we elaborately designed luminescent gold-silver bimetallic nanoparticles that could be rapidly transformed by the hepatic sinusoidal microenvironment rich in glutathione and oxygen, significantly different from monometallic gold nanoparticles that were rapidly sequestrated by Kupffer cells due to the much slower biotransformation. We found that the rapid sinusoidal biotransformation induced by the synergistic reactions of glutathione and oxygen with the reactive silver atoms could help bimetallic nanoparticles to avoid MPS phagocytosis, promote fast release from the liver, prolong blood circulation, enhance renal clearance, and increase disease targeting. With the fast biotransformation in sinusoids, liver sequestration could be turned into a beneficial storage mechanism for nanomedicines to maximize targeting.

Preparation of corn stover hydrothermal carbon sphere-CdS/g-C3N4 composite and evaluation of its performance in the photocatalytic co-reduction of CO2 and decomposition of water for hydrogen production

In this paper, a composite photocatalyst based on g-C3N4/CdS/corn straw hydrothermal carbon spheres was prepared by one-pot thermal synthesis method and applied for photocatalytic reduction of CO2 and hydrogen production. The morphology and structure of CdS/g-C3N4/ corn straw hydrothermal carbon spheres were characterized, which confirmed that the corn straw hydrothermal carbon spheres were successfully loaded into the heterojunction of g-C3N4 and CdS nanosheets. Through the study of photoelectric characteristics and DFT simulation, it was found that the energy band of g-C3N4/CdS/corn straw hydrothermal carbon spheres composite is reduced by 2.04 eV compared with that of pure g-C3N4 and CdS, and the photogenerated carrier transfer rate is accelerated. The Z-scheme heterostructure between g-C3N4 and CdS and the graphitized hydrothermal carbon spheres increase the surface active sites of the composite, leading to the generation of synergistic photocatalytic reaction. The photocatalytic experiment showed that g-C3N4/CdS/corn straw hydrothermal carbon spheres composite exhibited synergistic photocatalytic performance, while pure g-C3N4 and CdS did not. When the mass ratio of g-C3N4/CdS/corn straw hydrothermal carbon spheres was 1:0.1:0.5, the synergistic reaction efficiency was the highest, and the H2 yield was 250 μ mol·h−1·g−1, CO yield was 100 μ mol·h−1·g−1, and CH4 yield was 25 μ mol·h−1·g−1. By calculating the Gibbs free energy of the photocatalytic reaction and determining the possible mechanism of the synergistic reaction of g-C3N4/CdS/corn straw hydrothermal carbon spheres, it was inferred that the key step in the reaction was generation of CO.

Performance optimization and hydration mechanism of a clinker-free ultra-high performance concrete with solid waste based binder and steel slag aggregate

This study focuses on the feasibility of preparing clinker-free ultra-high performance concrete with solid waste based binder and steel slag aggregate. The influence of refining slag (RS) content, gypsum (DG) content, ground granulated blast furnace slag–hot stifle steel slag (GGBFS–HSSS) ratio and binder–sand ratio on the strength of UHPC were studied by orthogonal test, and then mainly discusses the reaction mechanism and hydration products of four solid wastes to further optimize the performance of clinker-free UHPC. The results showed the compressive and flexural strength of the Y1 samples could be increased to 108.39 MPa and 37.22 MPa respectively by optimizing RS content to 5%, DG content to 20%, GGBFS–HSSS ratio to 3:1, binder–sand ratio to 0.8. According to microanalyses (including XRD, semi-QXRD, FT-IR, TG-DSC, and SEM-EDS), the predominant hydration products of Z1 samples were ettringite and C–(A)–S–H gels, generated by the synergistic reaction of RS, GGBFS, HSSS and DG. In the first 2 days of curing, approximately 12.1% C12A7 and 1.3% gypsum was rapidly consumed, and 20.8% ettringite was simultaneously generated, which demonstrated the early strength was provided by the hydration of RS. During the 3–28 days curing, gypsum and Ca/(Si+Al) molar ratio of gels decreased by 10.9% and 0.61 respectively, and the weight loss rate was 3.85%, which indicated that gypsum reacted synergistically with HSSS and GGBFS during the process, resulting in the formation and growth of a large amount of C–(A)–S–H gels. The gels and ettringite intermingled together, making the structure more compact and the strength of UHPC increased.

Influence of Achiral Phosphine Ligands on a Synergistic Organo- and Palladium-Catalyzed Asymmetric Allylic Alkylation.

An unusual diastereodivergent stereoselective allylation reaction is presented. It consists of a palladium-catalyzed allylation reaction of an organocatalytically generated amino isobenzofulvene, where the diastereoselectivity is controlled by the electronic properties of a monodentate, achiral ligand on palladium. One major diastereoisomer is formed using triarylphosphines substituted with neutral or electron-donating substituents of the aryl group, while those with electron-withdrawing substituents favor the other diastereoisomer. The diastereoselectivity correlates with the Taft inductive parameter of substituents on the triarylphosphine ligand on palladium. The synergistic reaction involves both a catalytic secondary amine catalyst for the indene-aldehyde activation and the monodentate phosphine ligands on palladium, affording a highly enantioselective reaction with up to 98 % enantiomeric excess. Based on computational investigations, the role of the monodentate phosphine ligand on the diastereoselectivity is discussed.

Increased Scabies Incidence at the Beginning of the 21st Century: What Do Reports from Europe and the World Show?

Reports from various countries have described increasing numbers of scabies cases, especially in the past two decades. The epidemiological data for various world regions showed prevalence estimates ranging from 0.2% to 71%, with the highest prevalence in the Pacific region and Latin America. Therefore, geographically, scabies occurs more commonly in the developing world, tropical climates, and in areas with a lack of access to water. According to results from specific regions of the world, the greatest burdens from scabies were recorded for East Asia, Southeast Asia, Oceania, tropical Latin America, and South Asia. Among countries with the highest rates, the top 10 were Indonesia, China, Timor-Leste, Vanuatu, Fiji, Cambodia, Laos, Myanmar, Vietnam, and the Seychelles. From Europe, available data shows an increasing trend in scabies infestation, particularly evident among populations with associated contributing factors, such as those who travel frequently, refugees, asylum seekers, those who regularly lack drinking water and appropriate hygiene and are of a younger age, etc. This increase in observed cases in the last 10–20 years has been evidenced by research conducted in Germany, France, Norway, and Croatia, among other countries. In addition, increased scabies transmission was also recorded during the COVID-19 pandemic and may have been the result of increased sexual intercourse during that time. Despite all the available treatment options, scabies commonly goes unrecognized and is therefore not treated accordingly. This trend calls for a prompt and synergistic reaction from all healthcare professionals, governmental institutions, and non-governmental organizations, especially in settings where population migration is common and where living standards are low. Furthermore, the proper education of whole populations and accessible healthcare are cornerstones of outbreak prevention. Accurate national data and proper disease reporting should be a goal for every country worldwide when developing strategic plans for preventing and controlling the community spread of scabies.

Optimized Removal of Azo Dyes from Simulated Wastewater through Advanced Plasma Technique with Novel Reactor

Increasing attention has been paid to removal of aqueous contaminations resulting from azo dyes in water by plasma technology. However, the influence factors and removal mechanism of plasma technology were still obscure, moreover, energy consumption and oxidized degradation efficiency of plasma reactor were also inferior. In the present study, a comparative analysis was performed using 100 mg/L of Methyl Orange (MO) in the simulated wastewater with a novel plasma reactor to achieve the ideal parameters involving voltage, discharge gap, and discharge needle numbers. Therefore, the optimal removal rate for MO could be up to 95.1% and the energy consumption was only 0.26 kWh/g after the plasma treatment for 60 min, when the voltage was set as 15 kV, the discharge gap was 20 mm, and the discharge needle numbers was 5. Based upon the response surface methodology (RSM), the removal rate of MO was predicted as 99.3% by massive optimization values in software, and the optimum conditions were confirmed with the plasma treatment period of 60 min, the voltage of 14.8 kV, the discharge gap of 20 mm, and the discharge needles of 5. Plasma associated with catalysts systems including plasma, plasma/Fe2+, plasma/PS, and plasma/PS/Fe2+ were further investigated, and the best removal rate for MO reached 99.2% at 60 min under the plasma/PS/Fe2+ system due to simultaneously synergistic reactions of HO• and SO4•−. Moreover, it was also revealed that –N=N– bond was attacked and broken by active species like HO•, and the oxidized by-products of benzenesulfonic acid and phenolsulfonic acid might be generated, via the analysis of the variation in the absorbances through UV-Vis spectrophotometry during the plasma treatment. As a result, the advanced plasma technique in this study presented excellent efficacy for MO removal from simulated wastewater with low energy consumption.

Unraveling the Synergistic Reaction and the Deactivation Mechanism for the Catalytic Degradation of Double Components of Sulfur-Containing VOCs over ZSM-5-Based Materials.

The competitive adsorption behavior, the synergistic catalytic reaction, and deactivation mechanisms under double components of sulfur-containing volatile organic compounds (VOCs) are a bridge to solve their actual pollution problems. However, they are still unknown. Herein, simultaneous catalytic decomposition of methyl mercaptan (CH3SH) and ethyl mercaptan (C2H5SH) is investigated over lanthanum (La)-modified ZSM-5, and kinetic and thermodynamic results confirm a great difference in the adsorption property and catalytic transformation behavior. Meanwhile, the new synergistic reaction and deactivation mechanisms are revealed at the molecular level by combining with in situ diffuse reflectance infrared spectroscopy (in situ DRIFTS) and density functional theory (DFT) calculations. The CH3CH2* and SH* groups are presented in decomposing C2H5SH, while the new species of CH2*, active H* and S*, instead of CH3* and SH*, are proved as the key elementary groups in decomposing CH3SH. The competitive recombining of SH* in C2H5SH with highly active H* in dimethyl sulfide (CH3SCH3), an intermediate in decomposing CH3SH, would aggravate the deposition of carbon and sulfur. La/ZSM-5 exhibits potential environmental application due to the excellent stability of 200 h and water resistance. This work gives an understanding of the adsorption, catalysis, reaction, and deactivation mechanisms for decomposing double components of sulfur-containing VOCs.

Evaluating the Effects of Climate Change and Human Activities on the Seasonal Trends and Spatial Heterogeneity of Soil Moisture

Soil moisture (SM), as a crucial variable in the soil–vegetation–atmosphere continuum, plays an important role in the terrestrial water cycle. Analyzing SM’s variation and driver factors is crucial to maintaining ecosystem diversity on the Tibetan Plateau (TP) and ensuring food security as well as water supply balance in developing countries. Gradual wetting of the soil has been detected and attributed to precipitation in this area. However, there is still a gap in understanding the potential mechanisms. It is unclear whether the greening, glacier melting, and different vegetation degradation caused by asymmetrical climate change and intensified human activities have significantly affected the balance of SM. Here, to test the hypothesis that heterogeneous SM caused by precipitation was subject to temperatures and anthropogenic constraints, GLDAS-2.1 (Global Land Data Assimilation System-2.1) SM products combined with the statistical downscaling and Geographic detectors were applied. The results revealed that: (1) Seasonal SM gradually increased (p < 0.05), while SM deficit frequently appeared with exposure to extreme climates, such as in the summer of 2010 and 2013, and changed into a pattern of precipitation transport to western dry lands in autumn. (2) There was a synergistic reaction between greening and local moisture in autumn. SM was dominated by low temperature (TMN) in winter, warming indirectly regulated SM by exacerbating the thawing of glaciers and permafrost. The spatial coupling between the faster rising rate of TMN and the frozen soil might further aggravate the imbalance of SM. (3) The land cover’s mutual transformation principally affected SM in spring and autumn, and degradation accelerated the loss of SM replenished by precipitation. (4) Land cover responses were different; SM in grassland was less affected by external disturbance, while degraded woodland and shrub performed adaptive feedback under dry environments, SM increased by 0.05 and 0.04 m3/(m3 10a), respectively. Our research provides a scientific basis for improving hydrological models and developing vegetation restoration strategies for long-term adaptation to TP-changing environments.

Novel synthesis of reed flower-like SmMnOx catalyst with enhanced low-temperature activity and SO2 resistance for NH3-SCR

In this work, a novel co-precipitation coupled solvothermal procedure is proposed to prepare a SmMnOx catalyst (SmMnOx-CP + ST) with a reed flower-like structure for the selective catalytic reduction of NOx by NH3 (NH3-SCR). Over 90% NOx conversion and N2 selectivity was achieved at a low temperature range (25–200 °C), and 96% NOx conversion was achieved in the presence of 100 ppm SO2 at 75 °C. While the NH3-SCR of the SmMnOx catalysts prepared by co-precipitation (SmMnOx-CP) and solvothermal (SmMnOx-ST) methods performed much poorer than the SmMnOx-CP + ST catalyst. All catalysts were characterized by XRD, BET, SEM, XPS, H2-TPR, NH3-TPD, NOx-TPD, and FT-IR. The results revealed that the superior performance of the SmMnOx-CP + ST is due to the unique reed flower-like structure morphology, which endows the SmMnOx-CP + ST with the largest surface area, the strongest synergistic reaction of Sm and Mn, abundant surface oxygen species and surface active sites, and significantly enhances the redox ability. Furthermore, the amorphous reed flower-like structure showed strong short-range ordered interaction between the active components and weaken the formation of sulfates species. In addition, the highest content of Mn4+ and Mn3++Mn4+ greatly promotes the redox cycles of Sm2+↔Mn4+ and Sm2+↔Mn3+, and suppresses the production of sulfate species in the presence of SO2.

Surface etching and photodeposition nanostructures core-shell Cu2O@CuO-Ag with S-scheme heterojunction for high efficiency photocatalysis

Cu2O is one of ideal candidate photocatalyst, and it has attracted considerable attention owing to its low-cost and visible light responsive. Here, a core-shell structure of Cu2O@CuO-Ag with S-scheme heterojunction was delicately designed and synthesized for efficient photocatalytic degradation of the methyl orange (MO) and reduction of Cr(VI) under visible light. The shell of CuO and Ag nanoparticles were successfully close wrapped cube Cu2O core by the in situ topotactic oxidation of Cu+ in the surface of Cu2O and light deposition strategies, respectively. The Cu2O@CuO-Ag hybrid exhibits excellent photodegradation of MO activity and the reaction constant k is approximately 0.16 min−1, that is 8.20 times and 2.18 times higher than that for pure Cu2O and Cu2O@CuO, respectively. The Cu2O@CuO-Ag hybrid was also used to remove Cr(VI), and it exhibited not only strong adsorption ability, but also displayed remarkably promote photocatalytic performance in the absence of the sacrificial agents. The origin of the efficient activity of Cu2O@CuO-Ag hybrid photocatalyst was synergistic reaction to promote charge separation by S-scheme heterojunction designing and Ag acted as electron trap. This work provides a reference to design heterojunction photocatalysts based on Cu2O for photodegradation.

Sulfate radicals induced from peroxymonosulfate on electrochemically synthesized TiO2-MoO3 heterostructure with Ti-O-Mo bond charge transfer pathway for potential organic pollutant removal under solar light irradiation.

Here, a novel method for synthesis of heterostructured TiO2-MoO3 (MT) nanosheets photocatalyst by utilizing a facile electrochemical method and examined it's photocatalytic activity by the degradation of tetracycline hydrochloride (TCH), a model of organic pollutants, in the presence of peroxymonosulfate (PMS) under solar light irradiation (SL) was reported for the first time. The influence of several factors on the degradation efficiency including the initial concentration of TCH, solution pH, catalyst dosage, PMS concentration, and the existence of inorganic anions was explored. The MT-15/PMS system displayed a promising photocatalytic performance and up to 97% of TCH was degraded in 90min the rate of the degradation reaction of MT-15/PMS was the highest (0.05299 min-1) compared to 0.00251, 0.00337, 0.00546, 0.00735, 0.01337min-1of TiO2-P25, TiO2-P25/PMS, MoO3, MoO3/PMS, and MT-15 respectively. The enhancement can be attributed to several reasons. First, the 2D morphology of the optimized heterostructure photocatalyst plays a significant role in providing much more active sites on its surface. Next, the boosted light absorption efficiency and higher photoproduced electron-hole pair separation ability, induced by the unique direct transformation of photogenerated electrons from the valance band of TiO2 to the conduction band of MoO3 via the Ti-O-Mo bond formed at the interface of MT heterostructure. Finally, the appropriate accessible reactive sites for the activation of PMS together with the synergistic effect between activation of PMS and photocatalytic processes eased the production of active species for the degradation of pollutants. Based on the scavenger experiments and EPR analysis, hydroxide and sulfate radicals were found to be the dominant free radical active species in the degradation process. Furthermore, the synergistic degradation reaction mechanism was proposed.

Research Progress on Heterogeneous Reactions of Pollutant Gases on the Surface of Atmospheric Mineral Particulate Matter in China

Haze is the phenomenon of visibility degradation caused by extinction effects related to the physicochemical properties of atmospheric particulate matter (APM). Atmosphere heterogeneous reactions can alter the physicochemical properties of APM. Therefore, it is important to understand the atmospheric heterogeneous reactions of APM in order to reveal the cause of haze. Herein, the current situation, developmental trend, source, and composition of APM pollution in China are reviewed. Additionally, we introduce the reaction characteristics and key chemical processes of common inorganic, organic, and mixed pollutant gases on the surface of mineral particles. The effects of mineral particulate matter on aggregation, regulation, and catalysis in the formation of atmospheric aerosols and the synergistic reaction mechanism of SO2, NO2, O3, and VOCs on the surfaces of different mineral particles are summarized. The problems existing in the current research on heterogeneous reactions on the surfaces of mineral particles are also evaluated. This paper aims to gain a deep understanding of the mechanism of mineral particulate matter promoting the formation of secondary aerosols and attempts to provide theoretical support for effective haze control.