High Catalytic Activity For Reduction Research Articles

Enhanced electrochemical nitrate removal from groundwater by simply calcined-TNPs with modified surface characters

Simple and convenient preparation method with high catalytic reduction activity is crucial for the remediation of nitrate contamination. In this study, the innovation for fabricating a nanoelectrode was developed by calcinating the anodized plate to alter the surface crystalline phase of the material. The prepared calcined Ti nano-pores (TNPs) electrode could effectively remove up to 95.1% nitrate from simulated groundwater at 30 mA·cm–2 electrolysis for 90 min, while under the same conditions, the removal efficiency of nano electrode prepared by conventional methods was merely 52.5%. SEM images indicated that the calcined-TNPs nanoelectrode was porous with different pore sizes. The higher nitrate removal efficiency of TNPs-500 (95.1%) than TNPs-400 (77.5%) and TNPs-550 (93.4%) may resulted from the positive nonlinear response of the larger ECSA, the improved electron transfer and suitable surface structure, and not the “anatase-to-rutile” of surface TiO2 nanotubes. After 90 min of electrolysis, by using RuO2 as an anode and adding 0.3 g·L–1 NaCl solution, 87.5% nitrate was removed, and the by-products (ammonia and nitrite) were negligible. Increased temperature and alkaline conditions can enhance the nitrate removal, while higher initial nitrate concentration only improved the nitrate removal slightly. Moreover, The TNPs-500 electrode also exhibited excellent nitrate removal performance in real groundwater with the efficiency at 82.9% and 92.1% after 90 and 120 min, which were 0.87 (removal efficiency=95.1%), 0.92 (removal efficiency=100%) of the efficiency for simulated groundwater, indicating the widely applicable conditions of the TNPs-500 electrode. This approach of surface bonded elements and structure modification through calcination significantly improves catalytic activity, and will guide the simple designing of functional nanostructured electrodes with wide application conditions.

Synthesis of copper nanoparticles on cellulosic fabrics and evaluation of their multifunctional performances

Two different kinds of copper nanoparticles (CuNPs) (brown colour and greenish colour) were synthesised by using simple solution route and applied by exhaust method to achieve multidimensional functionalization on one of the most popular cellulose materials e.g., cotton fabric. The synthesised CuNPs imparted different colours to the said textile due to different conditions of synthesis and localized surface plasmon resonance. Physico-chemical characterizations of the synthesized nanoparticles were performed by using scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis whereas the optical properties of the nanoparticles were studied using UV–visible spectroscopy. The prepared CuNPs of both the types demonstrated very good antimicrobial activity up to 97%. In addition, cotton fabric treated with CuNPs showed very high catalytic activity for reduction of 4-nitroaniline (4-NA) in presence of sodium borohydride to phenylene diamine (4-PD). Washing durability and rubbing fastness of the treated fabric have also been measured by following standard testing methods and found to be very good with a rating 4.Graphical abstract

Highly efficient catalytic hydrogenation of nitrophenols by sewage sludge derived biochar

Finding a low cost and effective alternative to noble metal based catalyst has long been concerned in wastewater treatment and organic transformation. This work developed a highly efficient sewage sludge-based catalyst via a simple one-step pyrolysis method, and for the first time, applied it in the catalytic reduction of nitrophenols. Due to the higher content of graphitic nitrogen, abundant defect sites and low electron transfer resistance, sewage sludge derived biochar obtained at 800 °C (SSBC-800) exhibits the best catalytic performance, with the reaction rate of 0.48 min−1 and turnover frequency for 4-nitrophenol calculated to be 1.25 × 10−4 mmol•mg−1 min−1, which is comparable to or even superior than some reported noble metal-based catalyst. Moreover, SSBC-800 showed good recyclability of 90% 4-nitrophenol removal within 8 min after 4 runs, and maintained high catalytic activity in reduction of other substituent nitrophenols, such as 2-nitrophenol (0.54 min−1), 3-nitrophenol (0.61 min−1) and 2,4-dinitrophenol (0.18 min−1), and in real water samples, indicating its practical applicability. The electron paramagnetic resonance spectra and electrochemical characterization demonstrate that SSBC-800 accelerates the dissociation of BH4− to form active hydrogen, which is the main species responsible for 4-nitrophenol reduction, while electron transfer reaction involving the surface bound hydride derived from the intimate contact between BH4− and SSBC-800 plays an important role in this process. This research not only provides a novel valorization pathway for sewage sludge, but also sheds new light on further designing of carbon-based catalyst for nitrophenol reduction.

Fabrication of gold nanoparticles within hierarchically ZSM-5-based micro-/mesostructures (MMZ) with enhanced stability for catalytic reduction of p-nitrophenol and methylene blue

Gold nanoparticles (Au NPs) have received great attention in diverse catalytic reactions due to their excellent activity. However, the activity is severely relying on dispersion and size of Au NPs. Therefore, regulation of Au NPs for degradation of organic pollutants in water is of vital significance for environmental remediation. Herein, we developed microporous/mesoporous silica, MMZ, using ZSM-5 (SiO2/Al2O3 = 28) as structural constructing precursor and cetyltrimethylamoniumbromide (CTAB) as template via sequential dissolution-self-assembly strategy. The Au precursor is introduced into MMZ and ZSM-5 by ultrasound assisted impregnation and subsequent reduced for Au0 formation. The obtained materials were characterized by XRD, TEM, XPS, SEM, UV-DRS, N2 adsorption and TG/DTG techniques. XRD and TEM study revealed that up to1.0 wt% of Au can be well dispersed with smaller size of 2.8 nm in the material from MMZ (denoted as 1.0Au/MMZ), while serious aggregation and formation of large Au NPs occurs over ZSM-5 with the same Au loading (denoted as 1.0Au/ZSM-5). Catalytic studies also demonstrated that Au/MMZ has much higher catalytic activity for reduction of p-nitrophenol (P-NP) and methylene blue (MB) to p-aminophenol (P-AP) and leuco methylene blue compared with Au/ZSM-5 analogue and other reported Au-based catalysts previously. Moreover, Au/MMZ has good reusability and showed no change in its original catalytic performance till 7th cycles in reduction of P-NP and MB, which is attributed to stable structure and well dispersion of Au NPs over MMZ. Therefore, compared with other Au based catalysts used for catalytic reaction, this Au/MMZ is cheap and promising for industrial applications.

A One-Step Method for Preparation of Ru Nanoparticle Decorated on Three-Dimensional Graphene with High Catalytic Activity for Reduction of Nitroarenes

Ruthenium nanoparticles on nitrogen and sulfur-doped three-dimensional graphene (Ru@NSG) nanohybrid were prepared via a one-pot hydrothermal method with graphene oxide (GO) and RuCl3 as the raw materials and thiourea as a reducing-doping agent for the first time. The catalytic activity of nanohybrid was evaluated by the reduction of nitroarenes to the corresponding anilines. The effect of the weight ratio of Ru/GO was evaluated on catalytic activity. Moreover, in order to prove the role of the heteroatom substitution in graphene lattice, the Ru@NG and Ru@G hybrids were synthesized, and it was shown that the reaction yields would decrease in the presence of Ru@NG and Ru@G hybrids.

Spectroscopic investigation of chitosan-supported Cu2O/CuO nanocomposite; a separable catalyst for water-pollutants degradation

Abstract Designing nano-products using renewable/sustainable resources, while minimizing the use of hazardous reagents, is a major challenge. A new solid-state preparation route of chitosan-supported copper oxide using ascorbic acid (of biological origin) is developed. This method fulfills the environmental and economic requirements in terms of being a non-toxic, solvent-free, energy saving, and available for mass-production. The powder X-ray diffraction proves the formation of Cu2O/CuO nanoparticles. The scanning and transmission microscopy show the narrow size-distribution of the copper oxide particles. The Fourier transforms infrared and X-ray photoelectron spectroscopies provide evidence for the complexation of copper ions with hydroxyl and amino groups of chitosan. The catalytic activity of the chitosan-supported copper oxide nanocomposites is investigated toward a group of organic water-pollutants. The heterogeneous catalyst shows high catalytic activity in reduction of 4-nitrophenol, cationic, anionic dyes, and reactive dyes. The recyclability and reusability issues are efficiently treated here.

FeCeOx with improved activity for catalytic reduction of NO with NH3

An FeCeOx solid solution with an Fe/Ce molar ratio of 1 was obtained via a modified sol-gel method. The promotional effect of Fe3+ ions in the lattice of cubic CeO2 for catalytic reduction of NO with NH3 was studied. The NO conversion over the FeCeOx catalyst was obviously higher than those over CeO2 and Fe2O3 catalysts. FeCeOx was characterized by using XRD, TEM, and XANES, etc. The experimental results revealed that Fe substituted Ce in CeO2 to form an Fe–O–Ce solid solution with high activity for catalytic reduction of NO. The atomic and electric structures of the FeCeOx catalyst were studied to explain the enhanced catalytic activity.

Bone Char Mediated Dechlorination of Trichloroethylene by Green Rust.

Biochars function as electron transfer mediators and thus catalyze redox transformations of environmental pollutants. A previous study has shown that bone char (BC) has high catalytic activity for reduction of chlorinated ethylenes using layered Fe(II)-Fe(III) hydroxide (green rust) as reductant. In the present study, we studied the rate of trichloroethylene (TCE) reduction by green rust in the presence of BCs obtained at pyrolysis temperatures (PTs) from 450 to 1050 °C. The reactivity increased with PT, yielding a maximum pseudo-first-order rate constant (k) of 2.0 h-1 in the presence of BC pyrolyzed at 950 °C, while no reaction was seen for BC pyrolyzed at 450 °C. TCE sorption, specific surface area, extent of graphitization, carbon content, and aromaticity of the BCs also increased with PT. The electron-accepting capacity (EAC) of BC peaked at PT of 850 °C, and EAC was linearly correlated with the sum of concentrations of quinoid, quaternary N, and pyridine-N-oxide groups measured by XPS. Moreover, no TCE reduction was seen with graphene nanoparticles and graphitized carbon black, which have high degrees of graphitization but low EAC values. Further analyses showed that TCE reduction rates are well correlated with the EAC and the C/H ratio (proxy of electrical conductivity) of the BCs, strongly indicating that both electron-accepting functional groups and electron-conducting domains are crucial for the BC catalytic reactivity. The present study delineates conditions for designing redox-reactive biochars to be used for remediation of sites contaminated with chlorinated solvents.

Catalytic reduction of 1,4‐benzoquinone to hydroquinone via [FeFe]‐hydrogenase model complexes under mild conditions

AbstractBACKGROUNDHydroquinone (HQ) is an important fine chemical raw material and intermediate, which is widely used in chemistry industry. It is great significance to develop a new environmentally‐friendly synthesis method to produce HQ.RESULTSThree [FeFe]‐hydrogenase model complexes (μ‐budt)[Fe(CO)3]2[1; budt = SCH(CH3)CH2CH2)S], (μ‐budt)[Fe(CO)3][Fe(CO)2PPh3](2), and (μ‐bust)[Fe(CO)3]2 [3; bust = SCH(CH3)CH2CH2)S(O)] were synthesized by direct CO/L substitution or sulfur based oxygenation. The synthesized new complexes were fully characterized by FT‐IR, 1H NMR, 13C NMR and X‐ray crystallography. The electrochemical properties of these model complexes were investigated by cyclic voltammetry in CH2CI2 to evaluate the redox properties of the iron atoms. It was indicated that these new complexes are not only electrochemical catalysts for proton reduction of hydrogen, but also efficient catalysts for catalytic the transfer hydrogenation of BQ (1, 4‐benzoquinone) to prepare HQ under mild conditions. Especially,complex 2 exhibited the highest catalytic activity for reduction of BQ with methanol as the proton source, which gave a BQ conversion of 91 % and 72 % selectivity for HQ.CONCLUSIONSThe complex 2 can be a new type catalyst for catalytic reduction of BQ to HQ under mild reaction conditions. In addition, the Kinetics and mechanism were also investigated for a proposed transfer hydrogenation process. © 2019 Society of Chemical Industry

Facile and fast synthesis of a reduced graphene oxide/carbon nanotube/iron/silver hybrid and its enhanced performance in catalytic reduction of 4–nitrophenol

A facile, eco-friendly approach is proposed for fast preparation of a partially reduced graphene oxide/carbon nanotube/iron/silver hybrid (rGO/CNT/Fe/Ag) under ambient conditions. The partial reduction and exfoliation of GO, the ultrafast growth of CNT on the rGO surface, and the formation of AgNPs occurred simultaneously within 10–30 s using a domestic microwave oven. The morphology and structure of the rGO/CNT/Fe/Ag hybrid are discussed in detail, and a possible formation mechanism is proposed. The obtained rGO/CNT/Fe/Ag hybrid exhibited high catalytic activity for reduction of 4–nitrophenol (4–NP) by NaBH4 with a kinetic rate constant of 14.66 × 10−3 s−1, a normalized rate constant of 1884.31 s−1 × g−1 and a turnover frequency of 33.6 h−1 due to the synergistic effect of all consisting components in the hybrid. With a high surface area, GO serves as a good substrate for immobilization of more AgNPs, whereas rGO/CNT with a high electrical conductivity promoted the electron transfer in the reduction of 4–NP. AgNPs were the catalytic active sites for the reduction of 4–NP, whereas the presence of FeNPs and Fe3C facilitate for recovering and recycling the catalyst easily. Moreover, the rGO/CNT/Fe/Ag hybrid maintained high catalytic activity and stability after five cycles and easy reusability by an external magnet.

REDUCTION OF p-NITROPHENOL TO p-AMINOPHENOL BY USING NiO CATALYSTS: A COMPARATIVE STUDY

Different nickel oxide catalysts have been prepared by simple precipitation method using different nickel precursors and using surfactant sodium dodecyl sulfate (SDS) or without surfactant. The prepared catalysts have been characterized by using XRD and FT-IR. The particle sizes have been calculated by using the Scherrer equation. The nickel oxide catalyst prepared by using nickel acetate as precursor and surfactant SDS has shown less particle size as compared to other catalysts prepared by using other precursors. Also, nickel oxide catalyst prepared using nickel acetate precursor and surfactant SDS has shown higher catalytic activity for reduction of p-nitrophenol (PNP) to p-aminophenol (PAP) using sodium borohydride (NaBH 4 ). Also, for the said reaction effect of concentration of p-nitrophenol on catalytic efficiency has been studied.

Preparation of magnetically recoverable Fe3O4–graphene oxide catalyst by green method and its application for reduction of nitropyrimidine in aqueous medium

Magnetic graphene oxide (GO)/amino-functionalized Fe3O4 nanocomposite was prepared using tannic acid as binder. For this purpose, Fe3O4 nanoparticles were modified by phenylenediamine and GO was partially reduced and modified in presence of tannic acid. Nanocomposites were prepared under three different synthesis conditions. The morphology and chemical structure of the magnetic GO nanocomposites were studied by means of Fourier-transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and vibrating-sample magnetometry. The catalytic activity of the optimal GO/Fe3O4 nanocomposite was then studied using reduction of 2,4-dichloro-6-methyl-5-nitropyrimidine at different catalyst doses. The reaction time was probed using ultraviolet–visible (UV–Vis) absorption spectroscopy and thin-layer chromatography (TLC) analysis. The results demonstrated that, on increasing the catalyst dose from 1 to 7 mg, the reaction time decreased from 20 to 5 min. The synthesized product was also confirmed by nuclear magnetic resonance. The very low catalyst dose required, green media, and low temperature demonstrate that the as-prepared magnetic GO catalyst has high catalytic activity for reduction of nitropyrimidine to aminopyrimidine in aqueous medium.

Direct generation of Ag nanoclusters on reduced graphene oxide nanosheets for efficient catalysis, antibacteria and photothermal anticancer applications

There is considerable interest in understanding the catalytical, antibacterial, and photo-thermal properties of Ag nanoparticles. Herein, a simple, scalable and effective method is explored to generate Ag nanoclusters (∼3.57 nm) directly on reduced graphene oxide (rGO) (denoted as AgNC/GSH-rGO) using glutathione (GSH) as a green and mild co-reduction agent. Due to the good electrical conductivity of rGO, the extremely small particle size of Ag nanoclusters and the synergistic effect between Ag nanoclusters and rGO, high catalytic activity for reduction of 4-nitrophenol is achieved for AgNC/GSH-rGO at a very low Ag nanoclusters loading of 8.67 wt% on rGO. The conversion could reach 96.69% in 16 min and the apparent rate constant based on rGO is derived to be 0.55 min−1 when the concentration of AgNC/GSH-rGO is 0.04 mg mL−1. Moreover, the AgNC/GSH-rGO nanohybrids are also proven to be an efficient antibacterial and photothermal ablation agent for avoiding wound infection and cancer therapy applications.

Multifunctional (Fe0.5Ni0.5)S2 nanocrystal catalysts with high catalytic activities for reduction of I3− and electrochemical water splitting

It is important to synthesize environmentally friendly transition metal sulfide catalysts with superior performance for electrochemical water splitting and reduction of I3− in dye-sensitized solar cells (DSSCs). In this work, cubic (Fe0.5Ni0.5)S2 nanocrysals with a monodispersed size of ca. 10 nm were successfully prepared via a hot-injection reaction with a Schlenk line system. Because of the FeNi-oleate complex as transition metal source, no other by-products were produced. The (Fe0.5Ni0.5)S2 nanocrystal/carbon black composite with different nanocrystal contents was control fabricated. Because the composite possessed two merits, more catalytically active sites of nanocrystals and fast electron transfer of carbon black, it is a promising catalyst for electrochemical water splitting and reduction of I3− in DSSCs. As the counter electrode catalysts for reduction of I3−, DSSCs based on the composite with 57% (Fe0.5Ni0.5)S2 nanocrystal contents have a high power conversion efficiency of 6.71%, which was comparable to Pt-based DSSCs (7.05%). The electrochemical measurement showed that (Fe0.5Ni0.5)S2 nanocrystals had a good catalytic activity for reduction of I3−. As the catalytic electrode for hydrogen evolution reaction (HER), the composite electrode with 57% (Fe0.5Ni0.5)S2 nanocrystal contents displayed an overpotential of 250 mV to reach the current density of 10 mA cm−2 in alkaline solution. It retained good HER activity for 1000-cycle measurements. The density functional theory showed the free energy of hydrogen adsorbed on the Ni site near S defects was − 0.12 eV, which was smaller than that of the Fe site near S defects. So, the Ni site near S defects of (Fe0.5Ni0.5)S2 was the main catalytically active site for HER. Also, the (Fe0.5Ni0.5)S2 nanocrystals displayed good electrocatalytic activity for oxygen evolution reaction. This type of double metal sulfide with monodispersed size paves the way for new insight into earth-abundance catalysts for water splitting and I3− reduction.

Hierarchical Cu nanoparticle-aggregated cages with high catalytic activity for reduction of 4-nitrophenol and carbon dioxide

Hierarchical ∼10 nm Cu nanoparticle (NP)-aggregated sub-micro cage catalysts (diameter: ∼800 nm) with a hollow interior and porous shell were prepared from SiO2 encapsulated Cu2O nanoparticle aggregates (NPAs) using a facile and scalable method. The Cu cages were analyzed by field emission-scanning electron microscopy (FE-SEM), energy-dispersed X-ray (EDX), transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction (SAED), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). Owing to the small primary Cu NPs and characteristic porous shell and hollow interior, the Cu cages showed an extraordinarily high catalytic activity in the reduction of 4-nitrophenol by NaBH4 in aqueous solution. The activity factor (K = 520 s−1 g−1) is approximately 2.8 times greater than the previous highest K value of unsupported Cu catalysts. In addition, the excellent catalytic activity of the Cu cages in hydrogenation of CO2 to formate, with a TON value of 58 at 200 °C, was comparable to that of various noble metal-supported heterogeneous catalysts and surpassed the vast majority of homogeneous first-row transition metal catalysts.

Synthesis and characterization of Ag NPs templated via polymerization induced self-assembly

Spherical poly(acrylic acid)-block-polystyrene (PAA-b-PS) nano-objects were prepared via polymerization induced self-assembly (PISA) and used as templates for the synthesis of silver nanoparticles (Ag NPs). The PAA shells on the spheres acted as templates for the formation of immobilized Ag NPs by loading Ag + ions followed by reduction. The templates covered with discrete Ag NPs showed surface-enhanced Raman spectroscopy (SERS) effect as substrates for adenine detection and high catalytic activity for reduction of 4-nitrophenol to 4-aminophenol.

A simple route for preparing Au/mesoporous silica yolk/shell particles for Au-catalyzed reactions

We present a simple route to prepare mesoporous hollow silica particles containing an Au core, i.e., yolk/shell particles, by sol-gel and selective etching processes. Using tetraethoxysilane as a silica precursor, zinc acetate as a base catalyst, and cetyltrimethylammonium chloride as a soft template in the presence of Au nanoparticles, double-layered mesoporous shells were produced in one step. Elemental analysis showed that the inner shell consists of zinc silicate and the outer shell is pure silica. Au/mesoporous silica yolk/shell nanoparticles were obtained by selective etching of the zinc oxide phase with citrate buffer. The particle structure and composition were studied by transmission electron microscopy with energy disperse spectroscopy, UV-vis spectroscopy, X-ray diffraction, and nitrogen sorption experiments. Formation of double shells on the Au core in a single step was explained by a difference in the formation rates of the silica and zinc silicate phases. Au/mesoporous yolk/shell particles showed a high catalytic activity for reduction of 4-nitrophenol.

Anchoring of silver nanoparticles on graphitic carbon nitride sheets for the synergistic catalytic reduction of 4-nitrophenol

In this paper, a facile process was developed for anchoring of silver nanoparticles on graphitic carbon nitride sheets (Ag/g-C3N4) with high catalytic activity for reduction of 4-nitrophenol. The morphology and structure of the as-prepared Ag/g-C3N4 composite were investigated by FESEM, TEM, XRD and XPS. The reaction mechanism and the reduction kinetics of 4-nitrophenol under different light irradiation were systematically studied. The results showed that the obtained Ag/g-C3N4 composite exhibited a much higher electro/photo catalytic activity and stability for reduction of 4-nitrophenol. Significantly, due to the synergistic effect and interaction between highly dispersed Ag nanoparticles (Ag NPs, ∼7.2 nm) and lamellar g-C3N4, not only transfer of interfacial charge, but also the separation of photoinduced electrons occurred when the reaction was proceeded under light. In addition, the composite exhibited high stability and reusability during the cycling experiments. The results showed that the Ag/g-C3N4 composite is an effective and stable electro/photo catalyst for reduction of 4-nitrophenol.

Green synthesis of copper oxide nanoparticles/clinoptilolite using Rheum palmatum L. root extract: high catalytic activity for reduction of 4-nitro phenol, rhodamine B, and methylene blue

Copper oxide nanoparticles have been immobilized on the surface of clinoptilolite using Rheum palmatum L. root extract as a reducing and stabilizing agent in this work. FT–IR spectroscopy, UV–Visible spectroscopy, X-ray diffraction pattern, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy have been used to characterize clinoptilolite, copper oxide nanoparticles, and copper oxide nanoparticles/clinoptilolite. Catalytic activity of the prepared catalysts was studied in the reduction of 4-nitrophenol, methylene blue, and rhodamine B in the presence of sodium borohydride in water at ambient temperature. Copper oxide nanoparticles/clinoptilolite was found to be a highly active catalyst in the corresponding reactions. In addition, copper oxide nanoparticles/clinoptilolite can be recovered and recycled several times with no appreciable loss of catalytic activity.

Hybrids of Gold Nanoparticles with Core-Shell Hyperbranched Polymers: Synthesis, Characterization, and Their High Catalytic Activity for Reduction of 4-Nitrophenol

Hyperbranched core-shell structure can be constructed by the modification of hyperbranched polyethylenimine (HPEI) with different amide shells. Functionalized HPEI with acetic amide (HPEI-ACAm), propionic amide (HPEI-PRAm), butyric amide (HPEI-BUAm) and isobutyric amide (HPEI-IBAm) shells have been successfully prepared and used as protectors for gold nanoparticles (AuNPs). Novel AuNP composites were obtained through the non-covalent interaction between HPEI-XXAm and gold nanoparticles (XXAm represents ACAm, PRAm, BUAm or IBAm). The resulted AuNP composites can catalyze the reduction reaction of 4-nitrophenol by NaBH4. Interestingly, the catalytic activity of the AuNPs mainly depends on the structure of protectors and the degree of carbon chain arrangement denseness, which should affect the diffusivity of the reactants. In addition, the order of reaction rate is HPEI10K-IBAm0.80 > HPEI10K-ACAm0.80 > HPEI10K-PRAm0.82 > HPEI10K-BUAm0.83. It was found that the increase of the concentrations of the capping HPEI-XXAm polymers can enhance both the reaction rate and the turnover frequency (TOF) values. Furthermore, the reaction rate was accelerated with increasing the reaction temperature for AuNPs-HPEI10K-ACAm0.80 and AuNPs-HPEI10K-PRAm0.82 systems. Interestingly, the reaction rate was accelerated with elevating reaction temperature at the beginning but reached a plateau or decreased sharply for AuNPs-HPEI10K-IBAm0.80 and AuNPs-HPEI10K-BUAm0.82 systems, owing to the thermoresponsivity of the corresponding AuNP composites. As a consequence, the catalytic activity could be controlled by adjusting the different shells of the hyperbranched polyethylenimine.