Deposition Of Pd Nanoparticles Research Articles

Pd/MOF‐199: As an efficient heterogeneous catalyst for the Suzukie Miyaura cross‐coupling reaction

Successful deposition of Pd nanoparticles is described using MOF‐199 as a support. Various characterization techniques including FTIR, XRD, SEM, BET‐BJH, TG‐DTA, and NH3‐TPD were used to verify the efficiency of catalysts. Pd/MOF‐199 is utilized as a catalyst for Suzukie Miyaura reactions with reasonable to excellent reaction yields under reflux conditions in H2O: ethanol solvent.

Deposition of Pd nanoparticles on MWCNTs: Green approach and application to hydrogen sensing

A facile and green method is proposed for the deposition of palladium nanoparticles (NPs) on multiwalled carbon nanotube (MWCNT) thin films. Reduction and deposition of Pd NPs are achieved via oxidation of methanol on CNT supports under UV light irradiation. The proposed process yields uniformly distributed and highly crystalline Pd NPs on MWCNTs. When Pd-MWCNT thin films are exposed to hydrogen gas, H2 is adsorbed onto the Pd surface and spills over, followed by stable C–H bond formation via chemisorption of H atoms on the MWCNTs, resulting in increased electrical resistance due to widening of the band gap. As an electrical sensor, Pd-MWCNTs can detect H2 gas within a concentration range of 0.0004–80% in air at room temperature with a rapid response and quick recovery. Importantly, the proposed photochemical method can be extended to deposition of Pd NPs on thin films of other materials.

Preparation and characterization of highly active Pd nanoparticles supported Mn3O4 catalyst for low-temperature CO oxidation

Two methods were used to prepare Mn3O4 followed by deposition of Pd nanoparticles with 2 and 4 wt.%. The textural and structural properties were characterized by several methods. The XRD results showed the participation of MnO2 phase with small amount with tetragonal Mn3O4 due to hydrothermal treatment at 150 °C. Moreover, no changes in the textural properties of Mn3O4 due to the difference in preparation method or Pd nanoparticles deposition. TEM images showed different morphologies such as cubic, spheroid and plate-shaped structures. The XPS study confirmed the distribution of both Pd° and Pd2+ species on the Mn3O4 surface. The reducibility of pure Mn3O4 was greatly enhanced and shifted to lower temperatures after incorporation of Pd nanoparticles. The presence of Pd2+ may facilitate the providing of reactive lattice oxygen for CO oxidation by the support. The performance of the catalysts towards CO oxidation was much more enhanced as the Pd content increased to 4 wt. %. The results showed good stability and durability during the CO oxidation.

Rational design of Pd-TiO2/g-C3N4 heterojunction with enhanced photocatalytic activity through interfacial charge transfer

A hybrid heterojunction-based photocatalyst is synthesized by an electrostatic self-assembly strategy including surface modification and controlled metal deposition. The interfacial contact was made by mixing negatively charged anatase TiO2 nanoparticles with positively charged g-C3N4. Visible-light deposition of Pd nanoparticles largely on TiO2 was made possible due to the charge transfer from C3N4 (excited by visible light) to the conduction band of TiO2 reducing Pd ions on contact with its surface. In order to further test the efficiency of this cascade of electron transfer across the conduction bands of the two semiconductors, photocatalytic H2 production from water was studied. Upon optimizing the ratio of the two semiconductors, increased H2 production rates were observed and attributed to enhanced charge separation. Catalysts were studied by a variety of techniques in order to probe into their properties and link them to activity. The reaction rate, under visible-light excitation, of the best sample showed an 8-fold enhancement when compared to that of Pd-C3N4 in identical conditions and the highest apparent quantum yield of 31% was achieved by a 0.1%Pd/20%TiO2/C3N4 sample in a 420- to 443-nm range.

Sonochemical fabrication of Pd/TiO2-nanotubes/Ti plate as a green catalyst for oxidation of alkylarenes and benzyl alcohols

A facile and fast strategy has been employed to fabricate Pd nanoparticles supported on TiO2 nanotubes/Ti plate via sonochemical deposition. Microstructure studies showed the homogeneous deposition of Pd nanoparticles on the walls of TiO2 nanotubes/Ti plate. The synthesized plate was applied as a novel catalyst for the oxidation of benzyl alcohol and ethylbenzene derivatives. The results of catalytic experiments demonstrated that the modified plate was an efficient green catalyst for the oxidation of benzyl alcohols to benzoic acid derivatives in H2O. The oxidation of alkylarenes was carried out in EtOH:H2O (1:1) ended up with the formation of the corresponding ketone as the sole product. High yields and excellent selectivities were obtained for the oxidation reactions in green solvents using green oxidant. Superior catalytic activity, easy catalyst recovery, and reusability of the catalyst are some advantages of the modified PdNPs/TiO2 nanotubes/Ti plate, indicating a potential application of the catalyst in the industrial oxidation reactions.

Carbon Nanotubes-Supported Well-Dispersed Pd Nanoparticles for the Efficiently Selective Hydrogenation of Benzoic Acid to Synthesize Cyclohexane Carboxylic Acid

Pd and carbon nanotube (CNT) composites were prepared by well-dispersed deposition of Pd nanoparticles on commercial CNT, and applied to the selective hydrogenation of benzoic acid (BA) to synthesize cyclohexane carboxylic acid (CCA). The catalysts and the hydrogenation products were analyzed by XRD, TEM, TG, FTIR, UV-Vis absorption, GC and GC-MS, respectively. Hydrogenation process was also optimized through varying the reaction parameters. The results demonstrate that Pd/CNT catalysts possess the highest hydrogenation efficiency, give the full conversion of BA and 100.0% selectivity towards CCA at the optimal hydrogenation conditions, by comparing with some commercial hydrogenation catalysts and Pd/C catalysts with commercial carbonaceous supports. The excellent hydrogenation performance of Pd/CNT is attributed to the stable crystalline CNT support and the high dispersion of Pd nanoparticles. In addition, the protic solvent is also beneficial to lower the activation energy barrier of BA hydrogenation, and further to improve the hydrogenation rate. This work implies that CNT can be potentially chosen as an effective carbonaceous support to prepare Pd/C catalyst with an outstanding performance of BA selective hydrogenation.

Enhanced NO2 gas-sensing performance of Pd/ZnO-codecorated SnO2 nanorod sensors

SnO2 nanorods codecorated with Pd and ZnO were synthesized using a three-step process involving: the synthesis of SnO2 nanorods by the thermal evaporation of Sn powders followed by the sol–gel deposition of ZnO and Pd nanoparticles. The NO2 gas-sensing properties of the nanorods were examined. The nanorods were composed of primitive tetragonal-structured single crystal SnO2, while the ZnO and Pd nanoparticles were composed of wurtzite-structured ZnO single crystal and face-centered cubic-structured Pd single crystal, respectively. The Pd/ZnO-codecorated SnO2 nanorod sensors showed a remarkably enhanced response to NO2 compared to either ZnO or Pd-decorated SnO2 nanorod sensors. The responses of multiple networked Pd/ZnO-decorated SnO2 nanorod sensors were increased four to fivefold at NO2 concentrations ranging from 1 to 5 ppm Pd/ZnO-decorated SnO2 nanorod sensors which also showed shorter response and recovery times and higher selectivity than with ZnO or Pd-decorated SnO2 nanorod sensors. The NO2 sensing mechanism of the Pd/ZnO-codecorated SnO2 nanorods is also discussed.

In-situ reduction-derived Pd/3DOM La0.6Sr0.4MnO3: Good catalytic stability in methane combustion

To improve the stability of Pd-based catalysts at high temperatures, we herein report a novel strategy of first incorporating Pd to the lattice of three-dimensionally ordered macroporous La0.6Sr0.4MnO3 (3DOM LSMO) and then depositing Pd nanoparticles (NPs) on the surface of 3DOM LSMO directly by in-situ reducing 3DOM La0.6Sr0.4Mn1–xPdxO3 (3DOM LSMPdxO). Physicochemical properties of the materials were characterized by means of numerous techniques, and their catalytic activities were evaluated for the combustion of methane. Compared to the Pd-free sample, the doping of Pd was beneficial for improvement in catalytic activity, and the 3DOM LSMPd0.04O sample performed the best (T50% = 458 °C and T90% = 550 °C at a space velocity of 40,000 mL/(g h)). The in-situ reduction of the Pd-doped samples could generate the yPd/3DOM LSMO (y = 1.18–2.57 wt%) catalysts that exhibited good thermal stability and SO2-tolerant ability although their catalytic activities slightly decreased as compared to that prepared by the traditional impregnation method. The slight drop in activity of yPd/3DOM LSMO was due to the partial destroy of the LSMO perovskite after reduction at 500 °C. Among the Pd/3DOM LSMO samples, 1.18Pd/3DOM LSMO showed the best thermal stability and SO2-tolerant ability, which was attributed to the strong interaction between Pd NPs and 3DOM LSMO.

Oxidation by H2O(g) in the presence of H2(g) of UO2 doped with Pd nanoparticles

This work studies the influence of epsilon particles and metallic precipitates, simulated through the deposition of Pd nanoparticles on non-irradiated UO2, on the oxidation of the spent nuclear fuel (SNF). The presence of Pd nanoparticles favored the reduction by hydrogen of oxidized uranium phases located on the UO2 surface, decreased the oxidation of the UO2 by H2O in the absence of hydrogen, and, in the presence of hydrogen and water vapor, no oxidation of the UO2 by water was detected, contrasting experiments without Pd nanoparticles.

Pd@PtML Nanoparticles on Carbon-Supported WNi Substrates for the Oxygen Reduction Reaction

Several problems such as the high cost of Pt-based catalysts and their sluggish kinetics of the oxygen reduction reaction (ORR) are still hindering the broad application of proton exchange membrane fuel cells (PEMFC) [1,2]. The loss of activity of the catalysts is also a major issue. Most of the transition metals in Pt-based catalysts slowly dissolve in a strong acidic solution environment under high operating potentials, and their catalytic activity and efficiency are reduced [3]. Meanwhile corrosion of carbon causes a decrease in electrochemical surface area (ECSA) [4, 5], resulting in degradation of catalytic activity towards the ORR. In this work, we synthesized a platinum-monolayer (PtML) shell on palladium (Pd) core nanocatalyst supported by tungsten-nickel (WNi) deposited on Vulcan XC72R carbon black (Pd@PtML/WNi/C), which shows outstanding activity and durability toward the ORR. W tends to segregate to the surface of WNi substrate during a thermal treatment process in H2, which was then oxidized into tungsten trioxide (WO3) thin layer when the WNi/C powder was collected and transferred in air. This thin WO3 layer may protect the WNi and carbon substrates and is conductive in an acid solution [6, 7], thereby providing a suitable surface for further deposition of Pd nanoparticles (10 – 15 nm). The Pd nanoparticles were deposited on the WNi substrate by purging a CO gas in an ethanol solution containing PdCl2 and the WNi/C power. Electrochemical measurements were carried out after a PtML shell was placed onto the Pd nanoparticles through galvanic displacement of an underpotentially deposited Cu monolayer [8]. The STEM image and EDS mapping of each element in the Pd@PtML/WNi/C nanoparticles are shown in Fig. 1. W and Ni atoms were spread uniformly on the carbon support while Pt monolayer deposited by Cu-UPD method covered the Pd nanoparticle surfaces. The rotation disk electrode technique was used to examine the ORR activity of the Pd@PtML/WNi/C catalyst (Fig.2). The Pt and mass activity of the Pd@PtML/WNi/C catalyst were calculated to be 1.95 A/mgPt and 0.21 A/mgPGM, which are much higher than that of the commercial TKK 46.6% Pt/C catalyst (not shown). No discernible decrease in Pt mass activity and half-wave potentials were noticed after cycling for 5,000 and 30,000 times, indicating the superb durability of the Pd@PtML/WNi/C catalyst compared with that of the TKK Pt/C. More detailed results on RDE and MEA tests of the Pd@PtML/WNi/C catalyst will be discussed at the meeting. Acknowledgment This manuscript has been authored by employees/guest of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The publisher by accepting the manuscript for publication acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. This work was also performed in collaboration with N.E. Chemcat Corporation under contract no. NF-17-33. References G. Wu, K. L. More, C. M. Johnston, P. Zelenay, Science, 332, 443 (2011).K. Sasaki, H. Naohara, Y. Choi, Y. Cai, W. Chen, P. Liu, R. R. Adzic, Nat. Commun., 3, 1 (2012).K. Kuttiyiel, Y. Choi, K. Sasaki, D. Su, S. Hwang, S. Yim, T. Yang, G. Park, R. Adzic, Nano Ener., 29, 261 (2016).O. Naumov, S. Naumov, B. Abel, Á. Varga, Nanoscale, 2018, DOI: 10.1039/C7NR08545A.W. Xia, A. Mahmood, Z. Liang, R. Zou, S. Guo, Angew. Chem. Int. Ed., 55, 2650 (2016).Y. Liu, S. Shresha, W. Mustain, ACS Catal, 2, 456 (2012).Z. Cui, L. Feng, C. Liu, W. Xing, J. Power Sources, 196, 2621 (2011).R. R. Adzic, J. Zhang, K. Sasaki, M. B. Vukmirovic, M. Shao, J. X. Wang, A. U. Nilekar, M. Marikakis, J. A. Valerio, F. Uribe, Top. Catal., 46, 249 (2007). Figure 1

Electrocatalysis and Detection of Nitrite on a Pd/Fe₂O₃ Nanocomposite Modified Glassy Carbon Electrode.

An electrochemical palladium/ferric oxide (Pd/Fe2O3) nanocomposite modified glassy carbon electrode (GCE) was fabricated by hydrothermal method of Fe2O3 and electrochemical deposition of palladium nanoparticles, respectively. As-prepared Pd/Fe2O3 composite modified electrode exhibits enhanced electrocatalytic activity towards the catalytic oxidation of nitrite compared to Fe2O3, PdNPs modified electrodes and bare electrode. The parameters such as the influence of amount of Pd nanoparticles deposition onto the Pd/Fe2O3 modified electrode (ME) and effect of solution pH were investigated and discussed in detail. Under the optimal conditions, the Pd/Fe2O3 modified GCE can be used to detect nitrite concentration in a wide linear range of 10 and 1000 μM with the detection limit of 0.1 μM. The presence of Cu2+, Na+, Cl-, PO3-4 SO2-4, Mg2+ K+, NO-3, and NH+4 showed a trivial effect on the response of nitrite determination, revealing that developed modified electrode has an excellent anti-interference ability to common ions. It also shows good stability and reproducibility.

Investigation of the Catalytic Performance of Pd/CNFs for Hydrogen Evolution from Additive-Free Formic Acid Decomposition

In recent years, research efforts have focused on the development of safe and efficient H2 generation/storage materials toward a fuel-cell-based H2 economy as a long-term solution in the near future. Herein, we report the development of Pd nanoparticles supported on carbon nanofibers (CNFs) via sol-immobilisation and impregnation techniques. Thorough characterisation has been carried out by means of XRD, XPS, SEM-EDX, TEM, and BET. The catalysts have been evaluated for the catalytic decomposition of formic acid (HCOOH), which has been identified as a safe and convenient H2 carrier under mild conditions. The influence of preparation method was investigated and catalysts prepared by the sol-immobilisation method showed higher catalytic performance (PdSI/CNF) than their analogues prepared by the impregnation method (PdIMP/CNF). A high turnover frequency (TOF) of 979 h−1 for PdSI/CNF and high selectivity (>99.99%) was obtained at 30 °C for the additive-free formic acid decomposition. Comparison with a Pd/AC (activated charcoal) catalyst synthesised with sol-immobilisation method using as a support activated charcoal (AC) showed an increase of catalytic activity by a factor of four, demonstrating the improved performance by choosing CNFs as the preferred choice of support for the deposition of preformed colloidal Pd nanoparticles.

Deposition of Pd nanoparticles on TiO2 using a Pd(acac)2 precursor for photocatalytic oxidation of CO under UV-LED irradiation

In this study, 0.1–4 wt.% Pd-loaded catalysts were synthesized via thermal decomposition of palladium (II) acetylacetonate (Pd(acac)2) at 210–310 °C or its photodecomposition under UV-LED irradiation using anatase TiO2 as a support. The catalysts were characterized by X-ray fluorescence, AAS, TEM, XPS, and CO chemisorption analyses and tested for CO oxidation at room temperature in a batch reactor both in the absence and presence of UV-LED irradiation. The effects of the Pd(acac)2 decomposition method and Pd content on the dark catalytic and photocatalytic activities were studied.Decomposition of Pd(acac)2 occurred with the formation of the metallic (Pd0) and oxidized (PdO) forms of palladium on the TiO2 surface for both employed methods. The photodecomposition resulted in an increased amount of metallic palladium. All of the synthesized Pd/TiO2 catalysts completely oxidized CO to CO2 at room temperature. UV-LED irradiation with a total irradiance of 10.4 mW/cm2 in the UVA region increased the rate of CO oxidation by up to 5 times compared to dark catalytic oxidation. Photodecomposition of Pd(acac)2 resulted in a higher activity of the Pd/TiO2 catalysts compared to the thermal decomposition method. The rate of CO oxidation under UV irradiation and under dark conditions monotonically increased as the Pd content increased due to the stability of high dispersion of Pd particles even with a high Pd content. The maximum value of the photonic efficiency was estimated to be 5.9%.CeO2, SiO2, and Al2O3 were also employed for the deposition of Pd to investigate the effect of a semiconducting support. For the CeO2-based catalyst, the activity under UV irradiation was higher than in the dark, but this effect was much lower compared to that of catalysts based on TiO2. By contrast, no substantial difference in the CO oxidation rate in the absence and presence of UV irradiation was observed for the non-semiconducting supports, SiO2 and Al2O3, confirming the photocatalytic oxidation of carbon monoxide for the TiO2- and CeO2-based catalysts.

Nitrogen-doped carbon nanotubes as an excellent substrate for electroless deposition of Pd nanoparticles with a high efficiency toward the hydrogen evolution reaction

A highly efficient electrocatalyst for the hydrogen evolution reaction was developed using nitrogen-doped carbon nanotubes (N-CNTs) as a substrate for the electroless deposition of Pd nanoparticles (PdNPs). The N-CNTs were prepared with ionic liquid as a precursor through a programmed temperature method. The resulting PdNP@N-CNTs nanocomposite was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and electrochemical impedance spectroscopy (EIS). Electrochemical experiments show that the nanocomposite has high electrocatalytic activity toward hydrogen evolution with a current density of 32 mA cm−2 at an overpotential of 100 mV and a low Tafel slope (33 mV/dec) with excellent stability. The high catalytic activity and durability were considered to be due to N atoms incorporated into the carbon skeleton forming numerous active sites for the deposition of small and uniformly distributed Pd nanoparticles. This work provides a new way to prepare highly efficient electrocatalysts for hydrogen evolution.

Morphology and Size Effect of Ceria Nanostructures on the Catalytic Performances of Pd/CeO2 Catalysts for Methanol Decomposition to Syngas

Palladium is an active catalyst for the decomposition of methanol to syngas, and its chemical activity is largely affected by the interaction with the supporting substrate. Nanostructured cerium oxide can establish strong electronic interactions with finely dispersed palladium nanoparticles (NPs) leading to a substantial enhancement of their catalytic performance. To study this synergistic effect and connect it to structural parameters, we deposited Pd NPs on nanostructured cerium oxide particles exposing mainly the same (100) surface, but with different nanoshape and average dimension, and we have investigated their activity toward the methanol decomposition reaction. A systematic comparison of photoemission measurements taken at every step of the catalytic cycle allowed us to identify the most important factors that control the redox properties of the Pd/CeO2 systems and therefore the overall catalytic activity. Capitalizing on this knowledge it was possible to synthesize synergistic nanocatalysts with ...

Superhydrophobic and oleophilic micro‐nano hierarchical Pd‐decorated SiO2 layers

AbstractThis paper reports a novel fluorinated micro‐nano hierarchical Pd‐decorated SiO2 structure (hereafter called Pd/SiO2), which was formed by the deposition of Pd nanoparticles (NPs) on SiO2 microspheres. The SiO2 layers with microscale roughness were fabricated by electrospraying a solution prepared using the sol‐gel process. Subsequently, the Pd NPs were deposited using an ultraviolet reduction process. The resulting surfaces exhibited a micro‐nano hierarchical morphology. After fluorination, the micro‐nano hierarchical surface exhibited outstanding water repellency with a water contact angle (WCA) of 170° and a sliding angle <5°, indicating excellent superhydrophobic properties. The layers exhibited good long‐term durability and excellent ultraviolet resistance. Interestingly, the surface was oleophilic (CA of oil ~10°). These results show the potential of employing superhydrophobic fluorinated Pd/SiO2 layers in smart devices, such as self‐cleanable surfaces and intelligent water/oil separation systems.

Deposition of Pd nanoparticles on the walls of cathodically hydrogenated TiO2 nanotube arrays via galvanic displacement: A novel route to produce exceptionally active and durable composite electrocatalysts for cost-effective hydrogen evolution

Noble metal-based materials are inevitable components of cathodes for the hydrogen evolution reaction (HER) in future water electrolysis systems for clean hydrogen fuel production. However, designing active and durable nanostructured catalysts with low amount of costly noble metals is still a great challenge. Herein, we show that Pd nanoparticles (NPs) can be synthesized on the highly developed surface of anodically grown TiO2 nanotube (TNT) arrays by applying a simple galvanic displacement strategy. In a two-step procedure, air-annealed TNT arrays are first cathodically protonated and then partially reoxidized by Pd(II) ions from a PdCl2 solution while providing a scaffold for the metallic Pd deposit. Structural and electrochemical characterizations reveal that the Pd content and the width of the Pd-populated zone of the tube walls are in correlation with the tube length. The Pd@TNT composites display remarkable HER activity in 1 M HClO4 delivering a current density of −10 mA cm−2 at an overpotential of −38 mV and a Tafel slope of only −13 mV/dec. More impressively, the mass and apparent activity of the Pd@TNTs is superior to even commercial Pt/C at higher current densities. The composites also show stable chronopotentiometric response over 25 h and a negligible HER overpotential increase after potential cycling tests. The exceptional performance of the Pd@TNT cathodes is assigned to the unique semiconducting properties of the three-dimensional, interactive TNT supporting structures that, on the one hand, provide abundance of Pd active sites with optimized atomic hydrogen binding energy for the cathodic HER, but on the other hand, prevent anodic degradation of the Pd catalyst.

Aerogel sheet of carbon nanotubes decorated with palladium nanoparticles for hydrogen gas sensing

In the development of hydrogen sensors, it is required to meet the demands of both high sensor performance as well as the ease of fabrication for mass production. For this purpose we proposed a chemiresistive hydrogen sensors based on an aerogel sheet of carbon nanotubes decorated with palladium nanoparticles (CNT/Pd sheet). The fabrication process is straightforward that a dry-spun CNT aerogel sheet is suspended between concentric electrodes followed by depositing Pd nanoparticles on CNT sheets by thermal evaporation. The present CNT/Pd sheet sensors can detect hydrogen at concentrations as low as 2 ppm at room temperature with a detection range from 2 to 1000 ppm. The aerogel nature of CNT/Pd sheet contributes to low detection limit and broad detection range of the CNT/Pd sensor. Relations between hydrogen concentration and sensor response and response time, and the effects of temperature on sensor performance were investigated.

Effects of annealing temperature on the H2-sensing properties of Pd-decorated WO3 nanorods

The temperature of the post-annealing treatment carried out after noble metal deposition onto semiconducting metal oxides (SMOs) must be carefully optimized to maximize the sensing performance of the metal-decorated SMO sensors. WO3 nanorods were synthesized by thermal evaporation of WO3 powders and decorated with Pd nanoparticles using a sol–gel method, followed by an annealing process. The effects of the annealing temperature on the hydrogen gas-sensing properties of the Pd-decorated WO3 nanorods were then examined; the optimal annealing temperature, leading to the highest response of the WO3 nanorod sensor to H2, was determined to be 600 °C. Post-annealing at 600 °C resulted in nanorods with the highest surface area-to-volume ratio, as well as in the optimal size and the largest number of deposited Pd nanoparticles, leading to the highest response and the shortest response/recovery times toward H2. The improved H2-sensing performance of the Pd-decorated WO3 nanorod sensor, compared to a sensor based on pristine WO3 nanorods, is attributed to the enhanced catalytic activity, increased surface area-to-volume ratio, and higher amounts of surface defects.

Palladium Nanoparticles Anchored on Amine-Functionalized Silica Nanotubes as a Highly Effective Catalyst

The catalytic performance of supported heterogeneous catalysts is mainly dependent on their constitutive components including active species and supports. Therefore, the design and development of effective catalysts with synergistic enhanced effect between active sites and supports is of great significance. A facile in situ reduction approach to prepare amine-functionalized silica nanotubes (ASNTs)-supported Pd (ASNTs@Pd) composite catalyst is demonstrated in this article. Benefiting from the intrinsic physical and chemical properties of the ASNTs support and deposited Pd nanoparticles (NPs), the as-prepared ASNTs@Pd catalyst exhibits superior catalytic activity, stability, and reusability toward nitroarene reduction reactions. For catalytic reduction of 4-nitrophenol, the turnover frequency (TOF) is as high as 313.5 min–1, which is much higher than that of commercial Pd/C (5.0 wt %) and many noble-metal based catalysts reported in the last 5 years. In addition, a high TOF of 57.4 min–1 was also realized ...