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A new type of convenient, and environmentally friendly, Vanadium (V)-doped Bi 2 (O,S) 3 oxysulfide catalyst with different V contents was successfully synthesized via a simple and facile method. The obtained V-doped Bi 2 (O,S) 3 solid solution catalysts were fully characterized by conventional methods. The catalytic performance of the samples was tested by using the reduction of 2-nitroaniline (2-NA) in aqueous solution. The reduction/decolorization of methylene blue (MB) and rhodamine B (RhB) was also chosen to evaluate the universality of catalysts. It was observed that the introduction of V can improve the catalytic performance, and 20%V-Bi 2 (O,S) 3 was found to be the optimal V doping concentration for the reduction of 2-NA, MB, and RhB dyes. For comparative purposes, a related V-free Bi 2 (O, S) 3 oxysulfide material was synthesized and tested as the catalyst. The superior activity of V-doped Bi 2 (O,S) 3 over pure Bi 2 (O,S) 3 was ascribed mainly to an increase in active sites of the material and also due to the presence of synergistic effects. The presence of V 5+ as found from XPS analysis may interact with Bi atoms and enhancing the catalytic activity of the sample. In the catalytic reduction of 2-NA, MB and RhB, the obtained V-doped Bi 2 (O,S) 3 oxysulfide catalyst exhibited excellent catalytic activity as compared with other reported catalysts. Furthermore this highly efficient, low-cost and easily reusable V-doped Bi 2 (O,S) 3 catalyst is anticipated to be of great potential in catalysis in the future., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Developing an efficient catalyst is the key to selective catalytic reduction (SCR) of NOx by CO (CO‐SCR) to simultaneously address the pollution of toxic NOx and CO. Herein, a novel Rh/TiO2/Ti monolithic catalyst is designed and synthesized, featuring Rh species in the form of single atoms (Rh1) and clusters (Rhn). This catalyst overcomes the inhibitory effects of oxygen, achieving low‐temperature NO conversion. The investigation substantively contributes insights into the strategic manipulation of active metal components, emphasizing the potential of single‐atom/cluster catalysts to enhance efficiency. The Rh/TiO2/Ti catalyst has demonstrated exceptional catalytic efficacy, achieving 100% NO conversion at a low temperature of 190 °C in the presence of oxygen. Additionally, it exhibits remarkable stability and water resistance for practical applications. Moreover, comprehensive characterization confirms that Rh clusters and single‐atom sites play an important role in the selective adsorption of NO and CO molecules, promoting the formation of –N2O species and ultimately resulting in the complete conversion of NO and CO to N2 and CO2. This study not only provides valuable guidance for designing high‐performance CO‐SCR catalysts but also underscores the potential of single atoms/clusters catalytic systems in both fundamental research and industrial catalysis. [ABSTRACT FROM AUTHOR]

Activated carbon can be used as a catalyst for the reduction of Co(III)TETA to Co(II)TETA so as to maintain the ability of removing NO from gas stream with Co(II)TETA solution. Calcium nitrate has been utilized to treat activated carbon to improve its catalytic ability in the regeneration of Co(II)TETA. The biggest Co(III)TETA conversion is gained by the carbon being soaked in 0.3 mol/L calcium nitrate solution at 65°C for 12 h with a solid/liquid ratio of 1 g/50 mL followed being carbonized at 400°C for 2 h in nitrogen. The characterization with Fourier transform infrared spectroscopy, XPS, BET (Brunauer‐Emmett‐Teller) and Boehm titration indicates that the modification with calcium nitrate increases the specific surface area and acidic groups on activated carbon. The continuous experiments reveal that the NO removal efficiency obtained by the modified carbon is over 12% up to that by the original one. [ABSTRACT FROM AUTHOR]

Developing an efficient catalyst is the key to selective catalytic reduction (SCR) of NOx by CO (CO‐SCR) to simultaneously address the pollution of toxic NOx and CO. Herein, a novel Rh/TiO2/Ti monolithic catalyst is designed and synthesized, featuring Rh species in the form of single atoms (Rh1) and clusters (Rhn). This catalyst overcomes the inhibitory effects of oxygen, achieving low‐temperature NO conversion. The investigation substantively contributes insights into the strategic manipulation of active metal components, emphasizing the potential of single‐atom/cluster catalysts to enhance efficiency. The Rh/TiO2/Ti catalyst has demonstrated exceptional catalytic efficacy, achieving 100% NO conversion at a low temperature of 190 °C in the presence of oxygen. Additionally, it exhibits remarkable stability and water resistance for practical applications. Moreover, comprehensive characterization confirms that Rh clusters and single‐atom sites play an important role in the selective adsorption of NO and CO molecules, promoting the formation of –N2O species and ultimately resulting in the complete conversion of NO and CO to N2 and CO2. This study not only provides valuable guidance for designing high‐performance CO‐SCR catalysts but also underscores the potential of single atoms/clusters catalytic systems in both fundamental research and industrial catalysis. [ABSTRACT FROM AUTHOR]

• The currently available synthesis strategies and atmospheric environmental applications of monolithic aerogels have been summarized. • Recent developments of monolithic aerogels for the VOCs adsorption, CO 2 capture, catalytic oxidation of VOCs and catalytic reduction of CO 2 are highlighted. • Challenges and future opportunities for monolithic aerogels in atmospheric environmental purification field are proposed. Monolithic aerogels are promising candidates for use in atmospheric environmental purification due to their structural advantages, such as fine building block size together with high specific surface area, abundant pore structure, etc. Additionally, monolithic aerogels possess a unique monolithic macrostructure that sets them apart from aerogel powders and nanoparticles in practical environmental clean-up applications. This review delves into the available synthesis strategies and atmospheric environmental applications of monolithic aerogels, covering types of monolithic aerogels including SiO 2 , graphene, metal oxides and their combinations, along with their preparation methods. In particular, recent developments for VOC adsorption, CO 2 capture, catalytic oxidation of VOCs and catalytic reduction of CO 2 are highlighted. Finally, challenges and future opportunities for monolithic aerogels in the atmospheric environmental purification field are proposed. This review provides valuable insights for designing and utilizing monolithic aerogel-based functional materials. [ABSTRACT FROM AUTHOR]

New SCR catalysts based on Mn supported on simple or mixed aerogel oxides (Mn/ZrO2, Mn/CeO2-ZrO2 and Mn/CeO2-ZrO2-SO42−) were prepared for selective catalytic reduction of nitrogen oxide by ammonia (NO-SCR by NH3). One step sol gel method followed by supercritical drying process were used for elaborating the catalytic supports, however, Mn species were incorporated into aerogels via impregnation method. Structural, textural, acidic and redox properties of samples were studied using XRD; BET and porosity measurements; NH3-TPD and H2-TPR techniques. The results revealed that Mn/ZrO2 and Mn/CeO2-ZrO2 solids develop mesoporous texture, good crystallinity of zirconia tetragonal phase and nano-sized particles but exhibit a poor NO-SCR activity. The addition of SO42− induces a disorder in ZrO2 structure but it generates very active strong acid sites for the high temperature NO reduction. 100% NO conversion into N2 was achieved above 400 °C over the new Mn/CeO2-ZrO2-SO42− catalytic system. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) is a crucial industrial raw material, but the traditional Haber-Bosch process is energy-intensive and highly polluting. Electrochemical methods for synthesizing ammonia using nitric oxide (NO) as a precursor offer the advantages of operating under ambient conditions and achieving both NO reduction and resource utilization. Defect engineering enhances electrocatalytic performance by modulating electronic structures and coordination environments. In this brief review, the catalytic reaction mechanism of electrocatalytic NO reduction to NH3 is elucidated, with a focus on synthesis strategies involving vacancy defects and doping defects. From this perspective, the latest advances in various catalytic reduction systems for nitric oxide reduction reaction (NORR) are summarized and synthesized. Finally, the research prospects for NO reduction to NH3 are discussed. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) is a crucial industrial raw material, but the traditional Haber-Bosch process is energy-intensive and highly polluting. Electrochemical methods for synthesizing ammonia using nitric oxide (NO) as a precursor offer the advantages of operating under ambient conditions and achieving both NO reduction and resource utilization. Defect engineering enhances electrocatalytic performance by modulating electronic structures and coordination environments. In this brief review, the catalytic reaction mechanism of electrocatalytic NO reduction to NH3 is elucidated, with a focus on synthesis strategies involving vacancy defects and doping defects. From this perspective, the latest advances in various catalytic reduction systems for nitric oxide reduction reaction (NORR) are summarized and synthesized. Finally, the research prospects for NO reduction to NH3 are discussed. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) is a crucial industrial raw material, but the traditional Haber-Bosch process is energy-intensive and highly polluting. Electrochemical methods for synthesizing ammonia using nitric oxide (NO) as a precursor offer the advantages of operating under ambient conditions and achieving both NO reduction and resource utilization. Defect engineering enhances electrocatalytic performance by modulating electronic structures and coordination environments. In this brief review, the catalytic reaction mechanism of electrocatalytic NO reduction to NH3 is elucidated, with a focus on synthesis strategies involving vacancy defects and doping defects. From this perspective, the latest advances in various catalytic reduction systems for nitric oxide reduction reaction (NORR) are summarized and synthesized. Finally, the research prospects for NO reduction to NH3 are discussed. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) is a crucial industrial raw material, but the traditional Haber-Bosch process is energy-intensive and highly polluting. Electrochemical methods for synthesizing ammonia using nitric oxide (NO) as a precursor offer the advantages of operating under ambient conditions and achieving both NO reduction and resource utilization. Defect engineering enhances electrocatalytic performance by modulating electronic structures and coordination environments. In this brief review, the catalytic reaction mechanism of electrocatalytic NO reduction to NH3 is elucidated, with a focus on synthesis strategies involving vacancy defects and doping defects. From this perspective, the latest advances in various catalytic reduction systems for nitric oxide reduction reaction (NORR) are summarized and synthesized. Finally, the research prospects for NO reduction to NH3 are discussed. [ABSTRACT FROM AUTHOR]

We propose silver oxide as a cost‐effective and sustainable alternative to noble metals for the catalytic reduction of nitroaromatics. In the present investigation, we adopt a facile and green synthetic route for the synthesis of silver oxide nanostructures. The prepared nanostructures were found to crystallize in the cuprite phase and exhibit absorbance across the entire visible range of the electromagnetic spectrum. The catalytic potential of the silver oxide was evaluated by following the kinetics of nitrophenol reduction under ambient conditions and is observed to follow pseudo‐first order kinetics with the apparent rate constant kapp=4.24×10-3 ${{k}_{app}=4.24\ \times {10}^{-3}}$ s−1 at minimum concentration of the catalyst. We attribute the observed catalytic activity to the freshly generated catalytic surface featuring a partially reduced form of silver oxide during reaction. The findings highlight the efficacy of silver oxide in mitigating the environmental pollution originating from the recalcitrant nitroarenes. [ABSTRACT FROM AUTHOR]

[Display omitted] As model catalysts, it is necessary to study the relationship between the structure and properties of ultra-small metal nanoclusters (MNCs) and to reduce their steric hindrance as much as possible, e.g. preparing ultrasmall MNCs protected by ultra-short ligands. However, it is challenging to attain various MNCs with the same cores but different surface stabilizing ligands. Additionally, shortening the chains of protecting ligands will lead to larger MNC cores. Here, four different Pd NCs (Pd 6 (SC 4 H 9) 12 , Pd 6 (SC 8 H 17) 12 , Pd 6 (SC 6 (C 2)H 17) 12 and Pd 6 (SC 6 H 13) 12) were successfully synthesized by a slow synthesis process. All these clusters consist of six Pd atoms and are stabilized by 12 thiols with different chain lengths and steric hindrance. The catalytic properties of the as-prepared Pd 6 NCs were evaluated using the catalytic reduction of p-nitroaniline to p-phenylenediamine as a model reaction. The outcomes indicated that shortening the chain length of the protecting thiols could enhance the catalytic activity of the Pd 6 NCs. Notably, stable and active ultra-small Pd 6 clusters stabilized by ultra-short ligands (HSC 4 H 9) were successfully synthesized. Although the performance of Pd 6 (SC 4 H 9) 12 clusters protected by the ultra-short thiols is lower than that of commercial palladium on carbon (Pd/C), they display higher stability. Interestingly, the activity of Pd 6 NCs protected by ethyl-branched alkane thiols is also better than that of Pd 6 NCs protected by the alkane thiol ligands with the same chain length or the same number of carbon numbers. This work provides clear evidence that the catalytic activity of atomically precise MNCs can be controlled by regulating the surface stabilizing ligands. [ABSTRACT FROM AUTHOR]

4-nitrophenol (4-NP) is a frequently encountered toxic phenolic organic pollutant in water. It is important to develop a simple method to treat 4-NP. Small and monodispersed gold nanoparticles often have good catalytic performance of 4-NP. Hemoglobin (Hb) is a kind of common and important protein in organisms. Herein, highly biocompatible bovine hemoglobin-stabilized gold nanoparticles (Aun-Hb NPs) were synthesized using hemoglobin as a biological template. Then, the size, zeta potential, and composition of Aun-Hb NPs were investigated by transmission electron microscopy, dynamic light scattering, and X-ray photoelectron spectroscopy. The Aun-Hb NPs with small gold nanoparticles of about 1.4–2.4 nm had good catalytic capabilities in reducing 4-NP to form 4-aminophenol. Au20-Hb NPs demonstrated superior catalytic efficiency in the reduction of 4-NP when compared to other nanoparticles. Moreover, as-synthesized Au20-Hb NPs exhibited excellent biocompatibility through the MTT experiment. The method of preparation of gold nanoparticles offers one way to prepare metal nanoparticles for good potential catalytic applications of gold nanoparticles. [ABSTRACT FROM AUTHOR]

Due to the unique physicochemical properties of gold nanoparticles (AuNPs) decorated silica nanostructures (SiO2@AuNPs), they show great potential for applications in catalysis, biosensing, optical devices and medicine. It is essential to explore the catalytic effect of SiO2@AuNPs and the understanding of the essential process of catalytic reactions. We have prepared SiO2@AuNPs by loading small-sized AuNPs on surface-modified silica nanospheres. SiO2@AuNPs was used as a catalyst for the catalytic reduction of 4-nitrophenol (4-NP) in the presence of excess NaBH4, and the results showed that with the increase of the amount of catalyst from 30 to 100 μ l, the corresponding rate constant K app was increased from 6.44 × 10−3 to 1.45 × 10−2 s−1, and its TOF was as high as 1.326 × 103 h−1, and the catalytic rate could still be maintained at 87% after five cycles. By analyzing the morphology and size of the SiO2 supported AuNPs before and after the catalytic reaction, it can be seen that the atoms on the surface of small-sized AuNPs supported by silica have migrated during the catalytic process, which subsequently affects the catalytic efficiency of the structure. This study proves the good catalytic effect of SiO2@AuNPs structure and lays the foundation for its wider application. [ABSTRACT FROM AUTHOR]

In this study, a facile green synthesis method was adopted for the fabrication of magnesium oxide nanoparticles (MgO-NPs) from Calotropis gigantea (Aak plant) root extract which acted as a capping and reducing agent. The fabricated MgO-NPs were characterized by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR) and high resolution-scanning electron microscopy to determine optical, morphological and biological characteristics. UV-Vis spectra results showed an absorption peak at 317 nm whereas scanning electron microscopy showed spherical morphology of the synthesized MgO-NPs. FTIR spectra of the root extract confirmed the presence of phytochemicals, that is, amines, phenols, amides and ketones. Methylene blue (MB) dye was used as model contaminant to assess catalytic reduction potential of the synthesized MgO-NPs. Results obtained showed that biogenic MgO-NPs are suitable for catalytic reduction of MB dye and, when assembled in a sustainable manner, MgO-NPs have the potential to be used for the removal of toxic organic pollutants from industrial effluents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pd/WO 3 was designed for catalyzing the reduction of toxic pollutants. • DFT and XPS unravel a unique catalytic mechanism for the Cr(VI) reduction by formic acid. • Electron transfer at WO 3 /Pd interfaces optimizes Pd electronic states and upshifts d -band center. • Electron-deficient Pd boosts formic acid dissociation for efficient H* production. • Pd/WO 3 surpasses most Pd-based catalysts for Cr(VI) reduction with high TOF of 62.12 min−1. Through theoretical calculations, we show that integrating Pd with WO 3 nanomaterials can trigger the interfacial electron transfer from Pd to WO 3 , thus upshifting the d -band center (ε d) of Pd to optimize toxic hexavalent chromium (Cr(VI)) reduction. The elevated ε d can derive stronger chemisorption capability toward crucial formic acid molecules, notably lowering the thermodynamic energy barrier and speeding up the kinetics process. In order to realize this concept, we synthesized unique Pd/WO 3 nanofibers by loading Pd nanoparticles onto electrospun WO 3 nanofibers through an in situ photodeposition technique. Extensive structural, morphological, and X-ray photoelectron spectrometer (XPS) characterizations confirm the successful formation of the above nanofibers. As anticipated, the as-designed Pd/WO 3 nanofibers exhibit enhanced catalytic performance in the Cr(VI) reduction with a high turnover frequency (TOF) value of 62.12 min−1, surpassing a series of reported Pd-based catalysts. Such nanofibrous WO 3 -induced electronic modification of Pd with a high specific area leads to catalytic enhancement, providing a novel model for catalyst design. [ABSTRACT FROM AUTHOR]

5Cu-USY and Ce-doped 5Cu8Ce-USY zeolite catalysts were prepared by the conventional impregnation method. The obtained catalysts were subjected to the hydrothermal ageing process. The catalytic performance of the selective catalytic reduction of NOx with NH3 (NH3-SCR) was evaluated on both fresh and aged catalysts. Physical/chemical characterizations such as X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) were performed, along with detailed in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) experiments including CO adsorption, NH3 adsorption, and NO + O2 reactions. Results showed that, for the 5Cu-USY catalyst, hydrothermal ageing treatment could somehow improve the low-temperature SCR activity, but it also led to significant formation of unfavorable byproducts NO2 and N2O. Such an activity change can be attributed to hydrothermal ageing inducing the migration of isolated Cu+ species in the sodalite cavities towards the super cages of the USY zeolites. The increased content of Cu+ species in the super cages was beneficial for the low-temperature activity improvement, but, at the same time, it also facilitated ammonia oxidation at high temperatures. Ce doping after hydrothermal ageing has a "double-edged sword" effect on the catalytic performance. First of all, Ce doping can inhibit Cu species migration by self-occupying the internal cage sites; thus, the catalytic performance of 5Cu8Ce-USY-700H remains stable after ageing. Secondly, Ce doping introduces a CuOx–CeO2 strong interaction, which facilitates lattice oxygen mobility by forming more oxygen vacancies so as to increase the concentration of surface active oxygen. These changes, on the one hand, could help to promote further oxidative decomposition of nitrate/nitrite intermediates and improve the catalytic performance. But, on the other hand, it also causes the byproduct generation to become more severe. [ABSTRACT FROM AUTHOR]

As a new sustainable catalyst and green solvent, ionic liquid has important applications in catalytic reduction. In this study, four quinuclidinol-based quaternary ammonium ionic liquids (ILs)were at first prepared using simple procedures, and then they were used as catalyst for acetophenone reduction. The main catalytic conditions were studied and screened through a comparison among the reaction results. It showed that the highest yield of 1-phenylethanol was 88.6% when [MenQu]Cl was used as a catalyst; the ideal solvent was ethanol; the amount of catalyst was 20 mol%, and the reaction temperature was 25 °C. More substrates were employed to validate the universality of the developed method using such an IL. Moreover, potential reaction mechanisms and an IL recovery method were also suggested, which laid the foundation for its further applications in the field of sustainable chemistry and cleaner industrial production. [ABSTRACT FROM AUTHOR]

The catalytic performance of Perfluorosulfonic acid resin (PFSA), a solid superacid, was studied in the catalytic benzylation of 1,3‐dicarbonyl compounds with benzylic alcohols. The PFSA‐catalyzed reactions could proceed smoothly to provide the products under solvent‐free conditions or in toluene and dichloromethane, which gave moderate to excellent yields. Due to its high chemical stability, PFSA was quite stable under the reaction conditions and could be recovered at least eight times without significant reduction of its catalytic effect. Moreover, this reaction was investigated at a 20 mmol scale, which indicated the potential applicability of the large‐scale industrial synthesis. Finally, the mechanism of the PFSA‐catalyzed benzylation of 1,3‐dicarbonyl compounds with benzylic alcohols was also investigated. [ABSTRACT FROM AUTHOR]

Assessing competitive environmental catalytic reduction processes via NaBH4 is essential, as BH4− is both an energy carrier (as H2) and a reducing agent. A comprehensive catalytic study of the competition between the borohydride hydrolysis reaction (BHR, releasing H2) and 4-nitrophenol reduction via BH4− on M0- and M/M′ (alloy)-nanoparticle catalysts is reported. The results reveal an inverse correlation between the catalytic efficiency for BH4− hydrolysis and 4-nitrophenol reduction, indicating that catalysts performing well in one process exhibit lower activity in the other. Plausible catalytic mechanisms are discussed, focusing on the impact of reaction products such as 4-aminophenol and borate on the rate and yield of BH4− hydrolysis. The investigated catalysts were Ag0, Au0, Pt0, and Ag/Pt-alloy nanoparticles synthesized without any added stabilizer. Notably, the observed rate constants for the 4-nitrophenol reduction on Ag0, Ag-Pt (9:1), and Au0 are significantly higher than the corresponding rate constants for BH4− hydrolysis, suggesting that most reductions do not proceed through surface-adsorbed hydrogen atoms, as observed for Pt0 nanoparticles. This research emphasizes the conflicting nature of BH4− hydrolysis and reduction processes, provides insights for designing improved catalysts for competitive reactions, and sheds light on the catalyst properties required for each specific process. [ABSTRACT FROM AUTHOR]

In this study, a novel polyoxometalates-based metal-organic frameworks (POMOFs) microsphere, that is [Ni(phen)H2O]·V2O6 (phen is o-phenanthroline), have been successfully fabricated by one-pot simple hydro(solvent)thermal reaction through regulating different solvent ratios (H2O/EtOH). The experimental results show that the solvent effect has a significant effect on the micro-morphology and the catalytic activity of the materials. The dual-function in electrocatalytic hydrogen evolution and catalytic reduction of Cr6+ of the as-prepared POMOFs microspheres have been also studied. The POMOF(V,Ni)_3 catalyst prepared in the medium of pure ethanol have the best catalytic activity, in which the overpotential of 159 mV for the electrode is comparable to that of MoS2-based electrode material, and the rate constant k reaches 0.14 in the process of catalytic reduction of Cr6+. In this study, a novel polyoxometalates-based metal-organic frameworks (POMOFs) microsphere [Ni(phen)H2O]·V2O6 have been successfully fabricated by one-pot simple hydro(solvent)thermal reaction through regulating different solvent ratios. The dual-function in electrocatalytic hydrogen evolution and catalytic reduction of Cr6+ of the as-prepared sample have been also studied. [ABSTRACT FROM AUTHOR]

In this study, a novel polyoxometalates-based metal-organic frameworks (POMOFs) microsphere, that is [Ni(phen)H2O]·V2O6 (phen is o-phenanthroline), have been successfully fabricated by one-pot simple hydro(solvent)thermal reaction through regulating different solvent ratios (H2O/EtOH). The experimental results show that the solvent effect has a significant effect on the micro-morphology and the catalytic activity of the materials. The dual-function in electrocatalytic hydrogen evolution and catalytic reduction of Cr6+ of the as-prepared POMOFs microspheres have been also studied. The POMOF(V,Ni)_3 catalyst prepared in the medium of pure ethanol have the best catalytic activity, in which the overpotential of 159 mV for the electrode is comparable to that of MoS2-based electrode material, and the rate constant k reaches 0.14 in the process of catalytic reduction of Cr6+. In this study, a novel polyoxometalates-based metal-organic frameworks (POMOFs) microsphere [Ni(phen)H2O]·V2O6 have been successfully fabricated by one-pot simple hydro(solvent)thermal reaction through regulating different solvent ratios. The dual-function in electrocatalytic hydrogen evolution and catalytic reduction of Cr6+ of the as-prepared sample have been also studied. [ABSTRACT FROM AUTHOR]

This study encompasses the synthesis of gold nanoparticles (GNPs) captured on nanofibrous vinyl brushes (NVBs) using sepiolite nanoclay as a matrix. The diameter of GNPs was found to be 2–8 nm investigated by a particle-size analyzer. Due to the high surface reactivity, GNPs are more susceptible to agglomeration which reduces their efficacy as catalyst. A suitable support could be employed to arrest the discrete gold particles on its surface. The distinct textural morphology of sepiolite allows it to be a promising choice as support. Silanol groups on the surface of sepiolite nanofibers were consumed to graft vinyl brushes using hydrolyzed vinyl triethoxy silane. This grafting was characterized by FT-IR spectroscopy. Morphological studies of developed nanocomposites (AuNVBs) were conducted by TEM and FESEM revealing evidently the incorporation of well-distributed GNPs. XRD diffractograms have validated the connectivity of GNPs on NVBs surface. GNPs immobilized on the surface of NVBs are commendable candidates as catalyst to enhance the reaction rate for the conversion of 4- nitrophenol to 4- aminophenol. [ABSTRACT FROM AUTHOR]

In this study, we synthesized Au-Cu2O core–shell nanoparticles (Au@Cu2O NPs) with epitaxial Cu2O shell, which have highly improved catalytic performances in methyl orange reduction reaction. We have obtained Au@Cu2O NPs with different sizes at low temperatures by changing the amount of Cu2+ precursor. Both Au and Cu2O are catalytic materials, especially Cu2O, as a p-type semiconductor, whose catalytic ability depends on the crystalline facets. Catalytic reduction of methyl orange (MO) was used as a model system to explore the catalytic properties of Au@Cu2O nanocomposite. In comparison to pure Au and Cu2O NPs, the catalytic performance of Au@Cu2O has a noticeable improvement. The best catalytic rate was ~ 22 times faster than that of AuNRs and ~ 4 times than that of Cu2O NPs. By studying the catalytic mechanism, it is supposed that the Schottky barrier at the Au-Cu2O interfaces leads to the charge separation, which is beneficial to catalysis. Therefore, the Au@Cu2O NPs we designed with controllable shell thickness is an ideal composite material in the catalyst domain. [ABSTRACT FROM AUTHOR]

In this paper, silver nitrate was used as an oxidant to prepare polyaniline, polypyrrole, and poly(3,4-ethylene dioxythiophene)/silver composites through a simultaneous oxidation/reduction process. In addition, p-phenylenediamine was added with 1 mole% relative to the concentrations of the monomers to accelerate the polymerization reaction. The prepared conducting polymer/silver composites were characterized by scanning and transmission electron microscopies to study their morphologies; Fourier-transform infrared and Raman spectroscopies to confirm their molecular structures; and thermogravimetric analysis (TGA) to study their thermal stabilities. The silver content in the composites was estimated by energy-dispersive X-ray spectroscopy, ash analysis, and TGA. The conducting polymer/silver composites were utilized for the remediation of water pollutants through catalytic reduction. Hexavalent chromium ions (Cr(VI)) were photocatalytically reduced to trivalent chromium ions, and p-nitrophenol was catalytically reduced to p-aminophenol. The catalytic reduction reactions were found to follow the first-order kinetic model. Among the prepared composites, polyaniline/silver composite has shown the highest activity for the photocatalytic reduction of Cr(VI) ions with an apparent rate constant of 0.226 min–1 and efficiency of 100% within 20 min. Additionally, poly(3,4-ethylene dioxythiophene)/silver composite showed the highest catalytic activity towards the reduction of p-nitrophenol with an apparent rate constant of 0.445 min–1 and efficiency of 99.8% within 12 min. [ABSTRACT FROM AUTHOR]

Continuous electron‐hole transfer and the ability of nanoscale materials to absorb visible light are critical for pollutant catalytic reduction. Cobalt and copper co‐doped ZnO composites were shaped by the sol‐gel solution combustion (SG‐SC) approach. The x‐ray diffraction analysis confirmed the crystalline nature and interstitial doping of copper and cobalt in the zinc oxide lattice and the development of ZnO‐CuO local contact. The PL and DRS‐UV‐vis investigations showed the NCs' superior charge transfer and considerable redshift (from 3.17 to 2.21 eV) properties over ZnO. TEM and SEM‐EDS analyses confirmed the foam‐type surface morphology, elemental composition, and dopant distribution. The NCs showed greater potency than ZnO NPs in the catalytic reduction reactions of 4‐nitrophenol and methylene blue. Thus, the SG‐SC approach has the potential for industrially scalable catalytic pollutant reduction applications. [ABSTRACT FROM AUTHOR]

Decomposition of the environmentally harmful gas nitrous oxide (N2O) is usually performed thermally or catalytically. Selective catalytic reduction (SCR) is currently the most promising technology for N2O mitigation, a multicomponent heterogeneous catalytic system that employs reducing agents such as ammonia, hydrogen, hydrocarbons, or a combination thereof. This study reports the first homogenous catalyst that performs the reduction of nitrous oxide employing readily available and cheap light alcohols such as methanol, ethanol or ethylene glycol derivatives. During the reaction, these alcohols are transformed in a dehydrogenative coupling reaction to carboxylate derivatives, while N2O is converted to N2 and H2O, later entering the reaction as substrate. The reaction is catalysed by the low‐valent dinuclear ruthenium complex [Ru2H(μ‐H)(Me2dad)(dbcot)2] that carries a diazabutadiene, Me2dad, and two rigid dienes, dbcot, as ligands. The reduction of nitrous oxide proceeds with low catalyst loadings under relatively mild conditions (65–80 °C, 1.4 bar N2O) achieving turnover numbers of up to 480 and turnover frequencies of up to 56 h−1. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) have been synthesized using a variety of methods in recent years, and they have shown excellent catalytic activities. However, metal atoms show a high tendency to agglomerate in liquid media, making the single atom synthesis more difficult in liquid media. The synthesis of such metal single-atom catalysts that do not have strong ligand coordination is rarely reported in the literature. Herein, we report the facile synthesis of monodispersed Au atoms (Au1) through the reduction in HAuCl4 in 15-crown-5. The complete reduction in HAuCl4 was confirmed through UV-Vis spectroscopy. In addition, the Au was found in a zero valence state after reduction, which was confirmed through XPS and XANES results. Moreover, the dispersion of Au was confirmed as a single atom (Au1) through transmission electron microscopy and spherical aberration electron microscopy. The possible structure of this catalyst was proposed by matching the EXAFS results with the structure of Au1@15-crown-5 as -(OC2H4O)-AuCl2H2. The Au1@15-crown-5 showed high activity (TOF as high as 22,075) in the reduction in nitrophenol and nitroaniline to aminophenol and phenylenediamine by sodium borohydride. Because of the monodispersion of Au atoms, its performance is much better than noble nanoparticles and non-precious metal catalysts. [ABSTRACT FROM AUTHOR]

The SCR performance of V2O5-WO3/TiO2 SCR-catalysts characterized by different surface W density (2.1W/nm2 and 9.5W/nm2) and different surface V density varying in the range 1–8V/nm2 has been investigated in order to clarify existing controversies on the preferential involvement of electronic and geometric effects in the catalytic properties. It was found that tungsten has a weak effect on the VOx cluster size distribution through contraction of dilution effect. In contrast, the optimal interaction between W and V, when both reach their highest composition, appears to be a relevant parameter that can enhance their acidic properties and improve the catalytic efficiency in dry conditions. On the other hand, an absence of significant interaction leads to discontinuity due to deactivation. In the presence of steam, acidic properties are averaged, lowering the impact of the V to W ratio. Finally, the critical importance of acidic properties which outperform redox properties in the definition of active site is pointed out in the light of this study. [ABSTRACT FROM AUTHOR]

In the present study, we demonstrated a new strategy to decorate TiO2 nanoparticles on the surface of Nb2O5 nanorods to obtain a unique TiO2/Nb2O5 nanocomposite (NC). In order to achieve a high catalytic activity, TiO2/Nb2O5 NC was dispersed and anchored over reduced graphene oxide (rGO). The ratio between rGO and TiO2/Nb2O5 NC was varied to obtain two types of rGO/TiO2/Nb2O5 composites i.e. Cat-A and Cat-B. Cat-A (rGO:TiO2/Nb2O5 ~ 1: 0.3 wt/wt) showed higher photocatalytic degradation efficiency under visible light irradiation in comparison to Cat-B (rGO:TiO2/Nb2O5 ~ 1:0.6 wt/wt). In contrast, Cat-B showed enhanced catalytic activity for the reaction involving reduction of p-nitrophenol to p-amino phenol in the presence of NaBH4 as a reductant. The higher photocatalytic activity of Cat-A and catalytic reduction of Cat-B can be attributed to (i) high charge carrier mobility of rGO; (ii) strong acidity of crystal planes of Nb2O5 nanorods; and (iii) the synergistic effect of rGO and TiO2/Nb2O5 nanocomposites. [ABSTRACT FROM AUTHOR]

Developing efficient and cost-effective non-noble metal catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is of great importance. Herein, Co-promoted 1T-MoS2 nanoflowers were synthesized via a one-step hydrothermal method. The influence of Co content on the structure and catalytic performance of 1T-MoS2 was studied in detail. It was found that Co doping not only enhanced the electronic conductivity but also increased the hydrogen adsorption ability of 1T-MoS2. Meanwhile, the highest activity was achieved due to the synergy effect of Co-Mo-S and CoS2 active phase. In the catalytic reduction of 4-NP, the reaction rate constant of Co/1T-MoS2-0.3 was as high as 0.908 min−1 and the catalyst exhibited excellent stability after recycling five times. The present work provides new insights for the rational design of highly efficient metal-doped MoS2 catalysts towards 4-NP reduction in wastewater. [ABSTRACT FROM AUTHOR]

Some of the issues that humanity is facing include environmental degradation and an energy crisis. These problems are caused by population growth, rapid industrialization, and large amounts of waste generated as a result of various activities. Disposed tires contribute to landfilling because they do not degrade easily. Natural rubber trees are a source of latex, which is the primary component of tires. Tires can be recycled through pyrolysis to produce char, oil, and gas, but they contain high sulfur content. As a catalyst, 0%, 1.5%, 2.5%, 5%, 7.5% and 10% sodium carbonate of the feed material were used to produce tire pyrolysis oil (TPO). This study involved the investigation of temperature and catalytic sulfur reduction effects on the kinematic viscosity and specific gravity of TPO. These are critical properties to consider when assessing TPO's suitability for use in a diesel engine. The sulfur content decreased with increasing sodium carbonate, the specific gravity of TPO increased with increasing sodium carbonate, and kinematic viscosity decreased with increasing sodium carbonate until the catalyst was 2.5% and then started increasing proportionally with sodium carbonate for temperatures between 15 and 60 °C. [ABSTRACT FROM AUTHOR]

The coupled utilization of solar and thermal energy is considered an efficient way to improve the efficiency of CO2 reduction. Herein, palygorskite (Pal) clay is as a silicon source, while Co2+ is introduced to prepare two-dimensional Co2SiO4 nanosheets, and the excess of Co2+ leads to the growth of Co3O4 on the surface of Co2SiO4 to obtain an S-scheme Co2SiO4/Co3O4−x heterojunction, which facilitates the charge transfer and maintains higher redox potentials. Benefiting from black color and a narrow band gap, the cobalt oxide on the surface can increase the light absorption and produce a local photothermal effect. Under proper thermal activation conditions, the photoelectrons captured by the abundant oxygen vacancies can obtain a secondary leap to the semiconductor conduction band (CB), suppressing the recombination of electron-hole pairs, thus favoring the electron transfer on Co2SiO4/Co3O4−x. The composites not only have abundant oxygen vacancies, but also have a large specific surface area for the adsorption and activation of CO2. The yields of CH3OH on Co2SiO4/Co3O4−5% reach as high as 48.9 μmol·g−1·h−1 under simulated sunlight irradiation. In situ DRIFTS is used to explore the photocatalytic reduction CO2 mechanism. It is found that the thermal effect facilitates the generation of the key intermediate COOH* species. This work provides a new strategy for photothermal catalytic CO2 reduction by taking advantage of natural clay and solar energy. [ABSTRACT FROM AUTHOR]

The work designed a series of transition metal atoms anchored g-C 3 N 4 surface (TM@ g-C 3 N 4) as single-atom catalysts, and the excellent electrocatalyst with strong stability and high activity (V@g-C 3 N 4) was obtained. The NRR process on V@g-C 3 N 4 via distal pathways was the best and the corresponding limiting potential was only –0.115 V. The work also analyzed the charge density difference and crystal orbital Hamilton population to reveal the reason for the high catalytic activity of V@g-C 3 N 4. [Display omitted] • The NRR catalyst based on TM atoms anchored on C 3 N 4 is modeled. • The effects of TM-anchoring on the catalytic activity are investigated. • V@g-C 3 N 4 exhibits the highest NRR performance. • The reason for the high catalytic activity is further revealed. NH 3 is considered one of the most important chemicals, not only as an industrial feedstock for the production of fertilizers, but also as renewable carbon-free energy carrier. In recent years, electrocatalytic nitrogen reduction reaction (NRR), which uses N 2 and H 2 O as raw materials to synthesize NH 3 , is considered as one of the most promising methods for N 2 fixation. Therefore, the design and synthesis of NRR electrocatalysts with high catalytic performance is very important. Herein, using density functional theory method, 3d transition metal single atom anchored to g-C 3 N 4 as single-atom catalysts was studied for the catalytic reduction of N 2. The results found that V@g-C 3 N 4 exhibited high electrocatalytic activity and good catalytic selectivity. The limiting potential was only –0.115 V. Furthermore, the relevant electronic properties of V@g-C 3 N 4 were also analyzed. Our work can provide ideas and help to understand the reaction mechanism of single atom doped g-C 3 N 4 as NRR electrocatalysts with excellent catalytic performance. [ABSTRACT FROM AUTHOR]

Cu-MOF-1 heated to remove the free state water molecules in the structure can transcrystallize into Cu-MOF-2 , which can be applied to the temperature sensing performance using the color change. Secondly, Cu@1000 derived from Cu-MOF-1 has the advantages of uniformity of metal nanodispersion and abundant defect sites, which can accelerate the catalytic reduction of nitro compounds to amino compounds. [Display omitted] • Cu-MOF-1 is a new type of MOF and can be used as a template to prepare a variety of materials. • Cu-MOF-1 can convert to Cu-MOF-2 by SCSC which can be served as a temperature sensor. • Cu-MOF-1 can be served as a precursor to generate nanostructure by a single-step pyrolysis. • Cu@1000 showed efficient catalytic effect on 4-NP with a rate constant (Kapp) of 1.699 min−1 and also showed strong catalytic efficiency for all nitro compounds. In this paper, we have synthesized a new light blue crystal Cu-MOF-1 with Cu(II) as the central metal ion by using two mixed ligands, where N,N'-bis(3-pyridyl)adipamide (3-bpaa) and fumaric acid (H 2 FA). Taking this material as the precursor of the study, it is found that Cu-MOF-1 possesses a single-crystal-to-single-crystal (SCSC) transition phenomenon, using its structure in the free state of water molecules in the heating process will be dehydrated and thus transformed into dark blue crystal Cu-MOF-2. This color distinctive change can be intuitively identify the temperature conversion, and thus be applied to the direction of the temperature sensing. Moreover, using Cu-MOF-1 as a precursor, the carbon-based nanostructured materials (Cu@X) of Cu and Cu x O were derived from Cu-MOF-1 as a precursor in a straightforward and effective a single-step pyrolysis under different temperatures (400 °C, 600 °C, 800 °C and 1000 °C). As a result, Cu@1000 shown good activity (100 % conversion within 5 min) in the reduction of 4-nitrophenol (4-NP) by the presence of sodium borohydride (NaBH 4) at mild circumstances, yielding a rate constant (K app) of 1.699 min−1. This remarkable performance is due to the utilization of both the uniform distribution of Cu-based nanoparticals (CuNPs) in the carbon matrix and the abundance of defect sites in the surface. This paper describes innovative MOF-derived catalysts that can be employed in a range of useful applications. [ABSTRACT FROM AUTHOR]

To lessen air pollution led by diesel exhaust emission, regeneration of soot deposited in diesel particulate filter (DPF) by catalysts has attracted great attention. It is necessary to study effects of catalysts and soluble organic fraction (SOF) on soot oxidation using thermogravimetric analysis (TGA) for improving regeneration process. The diesel soot is simulated by Printex U (PU) particles, and the SOF originates from 0# diesel fuel and 15W lubricating oil. The TGA results are evaluated by the peak temperature Tp, comprehensive combustion index S and combustion stable index Rw, respectively. Compared with ZrO2 and CeO2 catalysts, the best catalytic effect on soot oxidation is achieved when the Pt catalyst is mixed with PU at 1:1 mass ratio. With the increasing of Pt catalyst, the comprehensive combustion performance of PU becomes inferior because of heat transfer poverty. Soot oxidation performance gets degradation after adding the simulative SOF. When the mass ratio of PU/Pt/15W reaches 1:1:0.1, the comprehensive combustion performance presents the comparatively superior state. The values of S and Rw indexes of PU/Pt/15W mixture at 1:1:0.1 mass ratio reach the largest of 9.459 × 10–8%2 min−2 °C−3 and 30.85 × 105, respectively. This work investigates the soot oxidation in the presence of catalyst and SOF based on previous researches, which benefits the optimization of catalytic regeneration strategy for DPF application. [ABSTRACT FROM AUTHOR]

The present work reported a novel strategy to construct supported cationic-polystyrene-resin-bound silver nanocomposites for enhanced catalytic reduction of 4-nitrophenol in an aqueous medium. The Fourier transform infrared spectroscopy (FTIR) was used as a model instrument for the study of catalytic reduction of 4-nitrophenol using cationic-polystyrene-resin-bound silver nanocomposite materials. The mechanism is based on the reduction of 4-nitrophenol to 4-aminophenol due to the electron transfer process that occurred between donor borohydride (BH4−) and acceptor 4-nitrophenol. The polystyrene resin provides support and surface area to increase the catalytic activity of silver nanoparticles. The diffused reflectance-Fourier transform infrared spectroscopy revealed the binding of silver particles onto the surface of cationic polystyrene resin beads. Furthermore, the catalyst was easily separated by the filtration and drying process and was able to reuse. A quantitative analysis of this work has also been performed. The linearity range, the limit of detection, and the limit of quantification obtained for the present method were 0.1 × 10−4 to 1.0 M, 0.6 M, and 2.1 M, respectively. Moreover, a good catalytic efficiency was found to be 96.8%. The advantages of the current method are its simplicity, sensitivity, rapidity, low cost, ease of preparation, and excellent catalytic efficiency to reduce 4-nitrophenol from an aqueous solution. [ABSTRACT FROM AUTHOR]

The primary objective of this research is to investigate the reduction of 4‐nitroaniline (4‐NA) and 2‐nitroaniline (2‐NA) using synthesized copper ferrite nanoparticles (NPs) via facile one‐step hydrothermal method as a heterogeneous nano‐catalyst. Nitroanilines were reduced in the presence and without the catalyst with a constant amount (100 mg) of reducing agent of sodium borohydride (NaBH4) at room temperature in water to amino compounds. To characterize the functional groups, size, structure, and morphology of as‐prepared magnetic NPs, FTIR, XRD, SEM, and TEM were employed. The UV‐Vis spectrum was utilized to explore the catalytic effect of CuFe2O4. The outcomes revealed that the synthesized CuFe2O4 as a heterogeneous magnetic nano‐catalyst catalyzed the reduction of 4‐NA and 2‐NA significantly faster than other candidate catalysts. The outcomes demonstrated that the catalyst catalyzed 4‐nitroaniline to para‐phenylenediamine (p‐PDA) and 2‐nitroaniline to ortho‐phenylenediamine (o‐PDA) with a constant rate of 7.49×10−2 s−1 and 3.19×10−2 s−1, and conversion percentage of 96.5 and 95.6, in 40 s and 90 s, sequentially. Furthermore, the nanoparticles could be recovered by a magnetic separation method and reused for six consecutive cycles without remarkable loss of catalytic ability. [ABSTRACT FROM AUTHOR]

The synthesis of an efficient catalytic system with a safe catalysis approach has always been the concern of researchers to eradicate the problems arising due to the discharge of colored pollutants by industries in water bodies. Herein, we synthesized a magnetically separable nanocatalyst, CSFe3O4@CeO2, by co-precipitation of CeO2 on the surface of magnetic Fe3O4 nanoparticles embedded in a chitosan hydrogel matrix. The synthesized catalyst was characterized by different analyses viz. FTIR, XRD, SEM–EDX and TEM. The CSFe3O4@CeO2 exhibited enhanced catalytic activity due to the unique synergism of adsorption and catalytic reduction for the removal of pollutants, namely methylene blue (MB), congo red (CR), and potassium ferricyanide using NaBH4 as a reducing agent. Further investigations of catalytic efficiency of CSFe3O4@CeO2 were done with MB by varying the catalyst dose, concentrations of MB and NaBH4. The reduction mechanism of MB to LMB (Leucomethylene blue) was studied and explained through adsorption reduction synergism. The reduction rate of MB in all catalytic experiments was determined by pseudo first-order kinetics. The adsorption isotherm data was best fit to Langmuir isotherm model indicated monolayer adsorption of MB on catalyst surface. The reusability of the catalyst with change in catalytic efficiency were also calculated to determine its economic feasibility. [ABSTRACT FROM AUTHOR]

We report on the design, synthesis, and characterization of the first silver hydride clusters solely protected and stabilized by dithiophosphonate ligands and their application for the in situ generation of silver nanoparticles towards the catalytic reduction of 4-nitrophenol in an aqueous system. The synthesis of the silver monohydride cluster involves the incorporation of an interstitial hydride using sodium borohydride. Poly-nuclear magnetic resonance and mass spectrometry were used to establish the structural properties. The structural properties were then confirmed with a single-crystal X-ray diffraction analysis, which showed a distorted tetracapped tetrahedron core with one hydride ion encapsulated within the core of the silver framework. Additionally, the synthesized heptanuclear silver hydride was utilized as a precursor for the in situ generation of silver nanoparticles, which simultaneously catalyzed the reduction of 4-nitrophenol. The mechanism of the catalytic activity was investigated by first synthesizing AgNPs, which was subsequently used as a catalyst. The kinetic study showed that the pseudo-first constant obtained using the cluster (2.43 × 10−2 s−1) was higher than that obtained using the synthesized AgNPs (2.43 × 10−2 s−1). This indicated that the silver monohydride cluster was more active owing to the release of the encapsulated hydride ion and greater reaction surface prior to aggregation. [ABSTRACT FROM AUTHOR]

Three different morphologies of CeO2 supports (nanoparticle, nanocube, and nanorod) were prepared by hydrothermal technique and further Mn2O3 metal was impregnated on CeO2 supports using wet‐impregnation methods, and their activity for NO reduction using NH3−SCR technique was analysed. The synthesized catalysts and supports were further characterized through scanning electron microscopy (SEM), Energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), X‐ray Photoelectron Spectroscopy (XPS), and transmission electron microscopy (TEM), and Brunauer‐Emmett‐Teller (BET). The catalytic performance of Mn2O3/CeO2‐nanoparticle has shown the highest conversion (76 %) compared to the other two catalysts in the temperature range of 50–450 °C. [ABSTRACT FROM AUTHOR]

In the catalytic reduction of various environment pollutants, cobalt-doped tin oxide, i.e., Co-SnO2 intercalated gelatin (GL) hydrogel nanocomposite was prepared via direct mixing of Co-SnO2 doped with GL. Then, it was crosslinked internally using formaldehyde within a viscous solution of gelatin polymer, which led to the formation of GL/Co-SnO2 hydrogel nanocomposite. GL/Co-SnO2 hydrogel nanocomposite was fully characterized by using field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR). The FESEM images indicate that the Co-SnO2 composite has a spherical structure on the GL matrix while EDX elucidates the elemental composition of each atom in the crosslinked GL/Co-SnO2 hydrogel nanocomposite. The GL/Co-SnO2 nanocomposite was checked for the reduction of various pollutants, including 2-nitro-phenol (2-NP), 2,6-dinitro-phenol (2,6-DNP), 4-nitro-phenol (4-NP), Congo red (CR), and methyl orange (MO) dyes with a strong sodium borohydride (NaBH4) reducing agent. The GL/Co-SnO2 nanocomposite synergistically reduced the MO in the presence of the reducing agent with greater reduction rate of 1.036 min−1 compared to other dyes. The reduction condition was optimized by changing various parameters, such as the catalyst amount, dye concentration, and the NaBH4 amount. Moreover, the GL/Co-SnO2 nanocomposite catalyst can be easily recovered, is recyclable, and revealed minimal loss of nanomaterials. [ABSTRACT FROM AUTHOR]

The green synthesis of silver nanoparticles (Ag NPs) for catalysis and biological applications has gained great interest. Natural elm pods are a type of food that possesses anti-inflammatory and pain-relieving effects. In this study, elm pod polysaccharide (EPP) was extracted from elm pods using hot water extraction for the first time. Biocompatible EPP-stabilized silver nanoparticles (EPP-Ag n NPs) were prepared by using a green synthesis method. The EPP-Ag 25 NPs had a hydrodynamic size of 40.9 nm and a highly negative surface charge of −27.4 mV. Furthermore, EPP-Ag 25 NPs exhibited high catalytic activity for the reduction of 4-nitrophenol, and the catalytic reaction followed a pseudo-first order kinetic equation. More importantly, the inhibition rate of EPP-Ag 25 NPs on Escherichia coli was 71 % when samples were treated with an 808 nm laser. Besides, EPP-Ag n NPs effectively inhibited the proliferation of tumor cells irradiated by an 808 nm laser. The improved performance of EPP-Ag n NPs was due to the good stability of EPP. Taken together, EPP-Ag n NPs had good stability, catalytic activity, antibacterial and antitumor ability under laser irradiation. EPP is a good stabilizer for many nanoparticles which have broad applications in the field of catalysis and biomedicine in the future. [Display omitted] • Elm pod polysaccharide (EPP) was extracted from elm pod for the first time. • The size of silver nanoparticles inside of EPP-Ag n NPs was from 22.5 to 30.0 nm. • EPP-Ag 25 NPs displayed high catalytic reduction reaction for 4-nitrophenol. • EPP-Ag 25 NPs exhibited stable photothermal conversion ability. • EPP-Ag 25 NPs had excellent antibacterial property against Escherichia coli. [ABSTRACT FROM AUTHOR]

In this study, the acid sites on the surface of the catalyst were quantitatively analyzed by pyridine adsorption infrared spectroscopy. When the molar ratio of V/P is 5, the molar ratio of HCl/V is 3, and the calcination temperature is 450 °C, the selective catalytic reduction effect of NO over VPO/TiO2 catalyst is the best (up to 99% at 200 °C), and the acidity of the catalyst is the highest, which is 5600 μmol·g−1. The results showed that the SCR activity of VPO/TiO2 catalyst increased with the increase of acidity at low temperature. Furthermore, the correlation between the denitration activity and the surface acid level was established by means of data fitting. The results showed that the low temperature denitrification activities of all VPO/TiO2 catalysts were positively correlated with the content of weak Lewis acid center (correlation coefficient > 0.9). In conclusion, this study provides a new method for analyzing the structure–activity relationship of the catalyst and provides some theoretical basis for the design of NH3-SCR catalyst. [ABSTRACT FROM AUTHOR]

Previous studies have shown that alkali metals catalyse the pyrolysis and gasification processes of biomass. However, whether alkali metals have the same catalytic effect on the reduction reaction of biochar with iron oxide has not been investigated. In this article, the effect of alkali metals on the reduction behaviour of biochar with iron oxide was investigated. It was shown that adding alkali metal carbonate could increase the reaction rate of CSC reduction stages 1 and 2, but it played an inhibitory role for the first and middle periods of stage 3. Moreover, adding alkali metals resulted in higher total CO2 gas production and reduced total CO gas production for the reduction reaction. The GB1 model was the best mechanistic model for stages 1 and 2 of the CSC-2K and CSC-2Na reduction reactions, while the C1 model was the best mechanistic model for stage 3. [ABSTRACT FROM AUTHOR]

Catalytic reduction represents a promising avenue for addressing some of the most pressing challenges in energy and environmental research. However, the absence of efficient electron management has emerged as a fundamental obstacle to practical applications. Piezocatalysis, a newcomer in charge carrier–based catalysis, holds the potential to overcome this bottleneck. By utilizing mechanical energy, the most ubiquitous and accessible source of energy in the environment yet underutilized, piezocatalysis enables efficient charge separation to retard recombination and thereby maximize charge utilization. This review discusses key achievements in piezocatalytic reduction for acquiring clean water, alternative fuels, and high-value-added chemicals. Challenges and potential research directions are outlined to stimulate further discussion. [Display omitted] • Key concepts on piezocatalytic reduction are discussed. • Key achievements in various piezocatalytic reductions are highlighted. • Key requirements to design potentially active piezocatalysts are summarized. [ABSTRACT FROM AUTHOR]

Lean exhausts aftertreatment has been the subject of numerous investigations due to ever stringent regulations on pollutants emissions such as that of NO x. Among aftertreatment technologies, the selective catalytic reduction of NO x by the hydrocarbons (HC-SCR) has been studied intensively, in particular by using Ag/Al 2 O 3 materials. The present work highlights that pretreatment of pristine Al 2 O 3 in warm water prior to Ag deposition allows to prepare catalysts of significantly higher (H 2 -)C 3 H 6 -SCR performance compared to conventional Ag/Al 2 O 3 catalysts. In addition, NO x -TPD-C 3 H 6 -SCR structure-activity correlations indicate that optimum composition of the Ag/Al 2 O 3 catalysts can be improved by about 50% in terms of Ag content for the first time. Unprecedented in-depth NMR investigations allow for the identification of the alumina sites of importance in the anchoring of Ag. These sites are µ1-OH groups located near the (100)/(110) l edge and then near the (110) b /(100) edge of Al 2 O 3 crystallites and bonded to octahedrally coordinated Al species. [Display omitted] • Remarkable NO x -TPD-C 3 H 6 -SCR structure-activity correlations are highlighted. • Optimum Ag loading on Al 2 O 3 is increased by about 50% compared to conventional samples. • In-depth NMR investigations allow to unravel Al 2 O 3 sites of importance in anchoring Ag. • µ1-OH groups located near the (100)/(110) l edge are the Ag anchoring sites of Al 2 O 3. [ABSTRACT FROM AUTHOR]

The multifunction substrate of SiO 2 @Ag hollow was designed to catalyze and in-situ monitor the reduction reaction of 4-nitro-thiophenol. The hollow structure is one of the key point for the enhanced SERS performance and catalytic activity. [Display omitted] • The SiO 2 @Ag hollow cube structure is a novel core–shell hollow structure that exhibits unique Localized Surface Plasmon Resonance properties that lead to the good SERS performance. • SiO 2 @Ag hollow cube presented superior catalytic performance and recycle stability in the 4-nitrophenol catalyzed reduction reaction. • SiO 2 @Ag hollow cubes act as the SERS substrates and catalyst for the reduction reaction of 4-nitrobenzenethiophenol. The reaction mechanism was investigated, the continuous irradiation could greatly promote the reaction process. Multifunctional substrate with high catalytic performance and in-situ monitoring ability is essential for exploring underlying reaction mechanism. In this contribution, a hybrid structure of hollow cubic SiO 2 @Ag (SiO 2 @AgHC) was prepared by anchoring Ag nano-particles on the surface of hollow SiO 2 cubes (SiO 2 HC). SiO 2 @AgHC possesses good catalytic activity for 4-nitrophenol (4-NP) reduction and reaction rate constant is 1.94 × 10−2 s−1. SiO 2 @AgHC also displays high Surface-enhanced Raman spectroscopy (SERS) sensitivity and the enhancement factor (EF) could be achieved as 5.7 × 104. Hence, the multifunctional substrates were successfully used as the SERS platform and catalyst to in-situ monitor the reduction reaction of 4-nitro-thiophenol (4-NTP). [ABSTRACT FROM AUTHOR]

The effect of sulfation on the catalytic performance of Mn-Co composite oxide catalyst for the selective catalytic reduction of NO x by NH 3 (NH 3 -SCR) has been investigated. Different concentrations of SO 2 have been used to sulfate Mn-Co composite oxide catalyst. The catalyst sulfated with 30 ppm SO 2 showed the widest activity temperature window, over which 80% NO x conversion was obtained in the temperature range of 80–350 °C. The sulfation leads to the appropriate redox property of Mn-Co composite oxide, thus improving the N 2 selectivity. Meanwhile, the sulfation contributes to the generation of more Brønsted acid sites, which is crucial for the enhanced activity. In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) demonstrated that the adsorbed NH 3 species on both Lewis acid and Brønsted acid sites, monodentate nitrite, bidentate nitrate and cis-nitrite species are the reactive intermediates in the NH 3 -SCR reaction. This study provides an idea for the regulating the activity temperature window of NH 3 -SCR catalyst to adapt to its practical application. [Display omitted] • Sulfation with a proper amount of SO 2 enhanced the NH 3 -SCR activity of Mn-Co catalyst. • The optimum concentration of SO 2 for the sulfation of Mn-Co catalyst is 30 ppm. • Sulfation leads to the formation of Brønsted acid sites on Mn-Co catalyst. • Adsorbed NH 3 , NH 4 +, monodentate nitrite, bidentate nitrate and cis-nitrite are reactive intermediates. [ABSTRACT FROM AUTHOR]

Carbon-supported bimetallic NiCo nanoparticles (NPs) have emerged as attractive catalysts and adsorbents for the reduction of 4-nitrophenol (4-NP) and separation of histidine-rich (His-rich) protein recently due to their low cost, high catalytic activity and good affinity for His-rich protein. In this study, new strongly coupled nickel–cobalt alloy/N,P,S co-doped carbon (NPSC) nanocages are rationally designed via chemical etching of the ZIF-67 dodecahedron with Ni2+ under sonication at room temperature, followed by poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) coating and subsequent carbonization treatment in a nitrogen atmosphere. When evaluated as a catalyst for 4-NP or an adsorbent for His-rich protein, the as-prepared NiCo@NPSC nanocages obtained at 700 °C show better performance than those obtained at other temperatures (500 and 900 °C). This improved catalytic effect is attributed to the controllable size and fine distribution of the NiCo NPs together with the effective contact between the catalysts and the N,P,S co-doped carbon matrix, leading to a superior catalytic effect on the reduction of 4-NP and the adsorption of His-rich protein. This catalyst design principle can be easily extended to other catalysis research fields. [ABSTRACT FROM AUTHOR]