NP Catalyst Research Articles

UiO-66(Zr)-2OH-Supported Pd0 NP Catalysts Accelerated a Fenton-Like Reaction: Iron Cycling and Hydrogen Peroxide Generation Achieved Simultaneously.

Both the sluggish kinetics of Fe(II) regeneration and usage restriction of H2O2 have severely hindered the scientific progress of the Fenton reaction toward practical applications. Herein, a reduction strategy of activated hydrogen, which was used to simultaneously generate H2O2 and accelerate the regeneration of ferrous in a Fenton-like reaction based on the reduction of activated hydrogen derived from H2, was proposed. Two types of composite catalysts, namely, Pd/UiO-66(Zr)-2OH and Pd@UiO-66(Zr)-2OH, were successfully prepared by loading nano-Pd particles onto the outer and inner pores of UiO-66(Zr)-2OH in different loading modes, respectively. They were used to enhance the reduction of activated hydrogen. The characterization results based on the analysis of scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy revealed that the materials were successfully prepared. By using a trace amount of ferrous iron and without adding H2O2, trimethoprim (C0 = 20 mg·L-1), as a target pollutant, could be nearly 100% degraded within 180 min in the reaction system composed of these two materials. The cycle of iron and the self-generation of H2O2 were verified by the detection of ferrous H2O2 in the system. Density functional theory calculation results further confirmed that the pore-filled Pd0 NPs, as the main catalytic site for Pd@UiO-66(Zr)-2OH, could produce H2O2 under the combined action of hydrogen and oxygen. The Pd@UiO-66(Zr)-2OH system had excellent stability after multiple applications (at least 6 cycles), all of which resulted in 100% removal of trimethoprim. The degradation efficiency of the Pd/UiO-66(Zr)-2OH system for TMP gradually decreased from 97 to 80% after six cycles. The results of electron paramagnetic resonance combined with classical radical burst experiments revealed the degradation pathways in the reaction system with hydroxyl radicals and singlet oxygen as the main reactive oxygen particles.

Sub-10 nm PdNi@PtNi Core–Shell Nanoalloys for Efficient Ethanol Electro-Oxidation

By controlling the structure and composition of Pt-based nanoalloys, the ethanol oxidation reaction (EOR) performances of Pt alloy catalysts can be effectively improved. Herein, we successfully synthesis sub-10 nm PdNi@PtNi nanoparticles (PdNi@PtNi NPs) with a core–shell structure by a one-pot method. The sub 10 nm core–shell nanoparticles possess more effective atoms and exhibit a synergistic effect which can lead to a shift in the d-band center and alter binding energies toward adsorbates. Due to the synergistic effect and unique core–shell structure, the PdNi@PtNi NP catalysts exhibit excellent electrocatalytic performance for ethanol oxidation reactions in alkaline, achieving 9.30 times more mass activity and 7.05 times more specific activity that of the state-of-the-art Pt/C catalysts. Moreover, the stability of PdNi@PtNi NPs was also greatly improved over PtNi nanoparticles, PtPd nanoparticles, and commercial Pt/C. This strategy provides a new idea for improving the electrocatalytic performance of Pt-based catalysts for EORs.

A Synthetic Approach to Synthesize Furan‐2‐Carboxylate Derivatives by Using a Magnetic Sodium Aluminate Catalyst

AbstractA novel and efficient procedure has been developed to synthesize furan‐2‐carboxylate derivatives through a one‐pot condensation of chloroacetate derivatives, 1,3‐diketones, and chloroform in the presence of magnetic sodium aluminate 40 wt. % (Aluminate NP‐40). The synthesized heterogeneous catalyst can be easily recovered from the reaction mixture by applying an external magnetic field. Magnetic aluminate NP catalysts provide a sustainable, environmentally friendly, and cost‐effective method for synthesizing furan‐2‐carboxylate derivatives. Additionally, the catalyst is stable and can be reused multiple times without losing its catalytic properties. High product yields in a short experimental time and easy workup are other advantages of the present method. All synthesized compounds were characterized by NMR spectroscopy.

Synthesis of Cr(OH)3/ZrO2@Co-based metal-organic framework from waste poly(ethylene terephthalate) for hydrogen production via formic acid dehydrogenation at low temperature

Recycling waste polyethylene terephthalate (PET) bottles into value-added ligand materials for synthesizing metal-organic frameworks (MOFs) derived catalysts is an eco-friendly and economically viable process. The waste PET bottles were readily broken down into 1,4-benzenedicarboxylic acid (BDC) ligands in a highly alkaline environment. Herein, we fabricated a Co@Cr(OH)3/ZrO2 catalyst via the carbonization of PET-derived UiO-66 metal-organic frameworks for the catalytic dehydrogenation of formic acid at low temperatures. The as-prepared Co@Cr(OH)3/ZrO2 catalyst provides a turnover frequency of 7685 h−1 for hydrogen generation (120 mL in 1.5 min) at ambient temperature. This is due to the uniform dispersion of the fine metal nanoparticle (NPs) (Co NPs, ∼3.75 nm) and the synergistic effect of the Co NPs and Cr(OH)3/ZrO2 supports. In addition, the characterization results indicate that porous Zr-MOFs may effectively enclose tiny particles, which is favorable for enhanced dehydrogenation performance. In addition, the Co@Cr(OH)3/ZrO2 catalysts demonstrated excellent stability against aggregation and were recyclable over seven cycles without any significant catalytic loss. Thus, this study provides a sustainable methodology for the development of MOF-derived, effective, and stable catalysts for formic acid dehydrogenation towards hydrogen production.

Single-walled carbon nanotube synthesis with RuRhPdIrPt high entropy alloy catalysts

Using high-entropy alloy nanoparticles (HEA NPs) composed of five platinum-group metals (5PGM), Ru, Rh, Pd, Ir, and Pt, as catalysts, we succeeded in growing single-walled carbon nanotubes (SWCNTs) via chemical vapor deposition (CVD). After CVD growth with C2H2 feedstock at 750 ℃ for 10 min, high-density SWCNTs were grown from 5PGM HEA NPs. The diameters of most SWCNTs were in the range of 0.83–1.1 nm, exhibiting the growth of small-diameter SWCNTs. Compared with monometal PGM catalysts, the SWCNT yield with the 5PGM HEA NP catalysts was much higher and was compatible even with those with Fe and Co.

Facile access to 1,2-disubstituted benzimidazoles and 2,3-dihydro-1H-perimidines using a biogenically synthesized single phase δ-MnO2 NP catalyst and its dye removal study

The synthesis of single phase δ-MnO2 NPs was carried out utilising an environmentally benign biogenic method. The prepared catalyst was utilized for benzimidazoles and dihydroperimidines synthesis and the dye removal study with exceptional catalytic activity.

(Poster Award - 3rd Place) Synthesis of Spherical Mesoporous Carbon (SMPC) Support and Electrochemical Properties of Pt/SMPC Catalyst

Introduction In Japan, extremely high cell performance is required for polymer electrolyte fuel cells (PEFCs) used in fuel cell electric vehicles after 2030 [1]. Therefore, it is of great importance to improve not only ORR activity, but also oxygen diffusivity of Pt and Pt-based cathode catalysts in PEFCs. In this study, a spherical mesoporous carbon (SMPC) with central mesopore’s diameter of 7 nm was synthesized and used for support of the Pt NP catalyst. Electrochemical properties of the Pt/SMPC catalyst were investigated. Experimental The SMPC support was synthesized by silica template method in which SiO2 precursor was in-situ formed [2]. 7 mL of tetrapropyl orthosilicate was added in a mixed solution (6 mL conc. NH3, 150 mL EtOH and 10 mL H2O) and stirred for 15 min. Then, 0.8 g resorcinol and 1.12 mL formaldehyde (37 wt.% aq.) were added and stirred at room temperature for 24 h. The precipitate was filtered and dried at 60°C overnight in air. The powder was heat-treated in a tube furnace at 850°C for 3 h in Ar atmosphere to obtain SiO2/SMPC. The SiO2/SMPC was dispersed in 10% HF aq. and stirred at room temperature for 2 h to remove silica template. The Pt/SMPC catalyst was synthesized by alcohol reduction method [3]. 300 mg SMPC was dispersed in a EtOH/H2O mixed solution (37.5 mL/250 mL), and Pt(NO2)2(NH3)2 (corresponding to 300 mg metallic Pt) dissolved in aqueous HNO3 was added, followed by refluxing at 90°C for 4 h in N2 atmosphere. The catalyst was filtered, washed and dried at 60°C overnight in air. Characterization of SMPC and Pt/SMPC was conducted by N2 gas adsorption, TG-DTA, XRD, TEM and TEM-EDX. The catalyst was loaded on GC-RDE. CV was recorded in Ar-saturated 0.1 M HClO4 at 25oC and at 50 mV/s. The ORR activity was evaluated by LSV performed in O2-saturated 0.1 M HClO4 at 25oC at 10 mV/s in the positive direction while rotating the GC-RDE at 1,600 rpm. Results and Discussion The weight percentage of silica template was 70% in SiO2/SMPC. Figure 1 shows SEM and TEM images of SiO2/SMPC before and after HF treatment. The SEM images clearly show that SiO2/SMPC and SMPC have spherical shape with mean diameter of 200 nm. In TEM images of SiO2/SMPC, center of the sphere is darker than edge and the edge became darker than the center after HF treatment, suggesting that the silica template NPs resided at the center of the sphere. TEM-EDX composition analysis of SiO2/SMPC is demonstrated in Fig. 2. Before HF treatment, Si was detected at the center of the sphere. After HF treatment, only C was detected with high intensities at the edge of the sphere. These results suggest that the SiO2/SMPC has a silica rich core-carbon rich shell structure. The thickness of the carbon rich shell was ca. 60 nm. The surface area of SiO2/SMPC was 510 m2/g and the area increased to 1,590 m2/g after HF treatment. Figure 3 shows pore size distribution of SiO2/SMPC. After HF treatment, SPMC support exhibited clear existence of mesopores with a central diameter of 7 nm.A cross-sectional TEM image of Pt/SMPC catalyst is depicted in Fig. 4. Pt NPs with Scherrer’s diameter of 2.3 nm were well dispersed over the carbon-rich shell, which indicates that mesopores in the carbon shell were well interconnected. The ECSA and the ORR activity of the Pt/SMPC catalyst were 92 m2/g and 450 A/g@0.9 V, respectively, the latter of which was similar to that of a commercially available Pt/C (TKK, TEC10E50E). Single cell tests using Pt/SMPC is now underway, and the results will be presented at the meeting.This study was partly supported by NEDO, Japan. Reference [1] M. Suzuki, https://www.nedo.go.jp/content/100888556.pdf (in Japanese).[2] Z. Deng et al., Nano Lett., 22, 9551 (2022).[3] M. M. Rahman et al., RSC Adv., 11, 20601 (2021). Figure 1

Amine-Functionalized SBA-15 Mesoporous Silica-Anchored Ni Nanocatalyst for CO2 Hydrogenation Reaction

Abstract: In this study, we successfully synthesized amine-functionalized SBA-15 mesoporous silicasupported Nickel nanoparticles (Ni NPs) and investigated their potential for CO2 transition to formic acid via high-pressure hydrogenation reaction. The metal-support interface between the Ni NPs and the amine-functionalized SBA-15 mesoporous silica was examined using various techniques, including BET, TEM, and XPS analyses. Our findings reveal a robust metal-support interaction between the NiNPs and the mesoporous silica substrate, highlighting the suitability of the catalyst for the CO2 conversion reaction. Additionally, the catalyst CAT$Ni-1 exhibited good catalytic activity over CAT$Ni-2 and CAT$Ni-3, and we were able to recycle them up to five runs with no significant reduction in catalytic activity. These results suggest that the synthesized Ni NP catalysts have the potential for large-scale CO2 conversion, contributing to the development of sustainable technologies for reducing greenhouse gas emissions.

Room-Temperature Synthesis of Biogenic δ-MnO2 NPs for the Dehydrogenative Coupling of Diamines with Alcohols for Benzimidazole and Quinoxaline Synthesis: An Efficient Catalyst for Electrochemical Applications.

An efficient, unique, and eco-friendly biogenic synthesis of single-crystalline δ-phase manganese oxide nanoparticles (MnO2 NPs) using Gliricidia sepium leaves (GSL) extract at room temperature has been revealed for the first time. The active chemicals present in the GSL extract were found to serve as both reducing and stabilizing agents. The catalyst shows an excellent surface area of 301.13 m2 g-1, a mean pore diameter of 4.01 nm, and 39.97% w/w of active metal content. The reactivity of the synthesized catalyst was demonstrated by achieving a one-pot synthesis of benzimidazoles and quinoxalines via an acceptorless dehydrogenative coupling strategy utilizing biorenewable alcohols. The release of hydrogen gas was observed as the only side product and proven by its successful utilization for alkene reduction which supports the mechanistic elucidation. The release of hydrogen gas as a useful byproduct highlights the scientific importance of the present methodology. Additionally, gram-scale synthesis and catalyst recyclability studies are deliberated. Importantly, the δ-MnO2 NP catalyst exhibited superior catalytic activity and high durability toward hydrogen evolution reaction in alkaline media, highlighting the dual use of the catalyst. The δ-MnO2 NPs attain the current density of 10 mA/cm2 at an overpotential of 154 mV with a Tafel slope of 119 mV/dec.

Ligand-Aided Glycolysis of PET Using Functionalized Silica-Supported Fe2O3 Nanoparticles.

The development of efficient catalysts for the chemical recycling of poly(ethylene terephthalate) (PET) is essential to tackling the global issue of plastic waste. There has been intense interest in heterogeneous catalysts as a sustainable catalyst system for PET depolymerization, having the advantage of easy separation and reuse after the reaction. In this work, we explore heterogeneous catalyst design by comparing metal-ion (Fe3+) and metal-oxide nanoparticle (Fe2O3 NP) catalysts immobilized on mesoporous silica (SiO2) functionalized with different N-containing amine ligands. Quantitative solid-state nuclear magnetic resonance (NMR) spectroscopy confirms successful grafting and elucidates the bonding mode of the organic ligands on the SiO2 surface. The surface amine ligands act as organocatalysts, enhancing the catalytic activity of the active metal species. The Fe2O3 NP catalysts in the presence of organic ligands outperform bare Fe2O3 NPs, Fe3+-ion-immobilized catalysts and homogeneous FeCl3 salts, with equivalent Fe loading. X-ray photoelectron spectroscopy analysis indicates charge transfer between the amine ligands and Fe2O3 NPs and the electron-donating ability of the N groups and hydrogen bonding may also play a role in the higher performance of the amine-ligand-assisted Fe2O3 NP catalysts. Density functional theory (DFT) calculations also reveal that the reactivity of the ion-immobilized catalysts is strongly correlated to the ligand-metal binding energy and that the products in the glycolysis reaction catalyzed by the NP catalysts are stabilized, showing a significant exergonic character compared to single ion-immobilized Fe3+ ions.

Synergistic effect of sub-5 nm Fe nanoparticles supported on nanoporous carbon for catalyzing hydrogen storage properties of Mg(BH4)2

This study investigates synergistic effects of sub-5 nm Fe nanoparticles (FeNPs) supported on mesoporous carbon (MC) for catalyzing hydrogen storage properties of Mg(BH4)2 (MBH). The study compares two methods for dispersing Fe NPs in MC: (i) ultrasonication nanoconfinement (un) and (ii) post-nanoconfinement (pn) via stirring. Based on the results, it is found that the ultrasonication nanoconfinement method can effectively disperse the FeNPs with 5 nm in MC support (FeNP-un-MC), later which can efficiently confine MBH (FeNP-un-MC@MBH system). The hydrogen (H2) desorption properties of the FeNP-un-MC@MBH system were found to be better than that of post-confinement-mediated FeNP-pn-MC@MBH system. For instance, H2 started to desorb from the FeNP-un-MC@MBH system at only 66 °C (Tonset) and reached its peak at ∼153 °C, compared to 270 °C (Tonset) and its peak ∼350 °C for pure MBH, respectively. The ultrasonication-mediated nanoconfined FeNP-un-MC@MBH system released a total of 7.01 wt% H2 within 90 min at 350 °C. The study shows that the activation energy (Ea) of FeNP-un-MC@MBH is 19.57 kJ/mol, achieved due to the improved dehydrogenation kinetics of MBH. These improvements are due to the synergistic effects of nano-compartmentalization and highly dispersed Fe NP catalyst sites in the MC support. The research emphasizes the promising application of ultrasonication-mediated nanoconfined Fe NPs in mesoporous carbon which can be used as an effective catalyst for enhancing the hydrogen storage properties of metal-based hydrides (MBH).

Reversible ligand exchange of triphenylphosphine with thiols on gold nanoparticles for Janus modification and catalyst recycling

Separation and regeneration of ultrafine catalysts in reaction system still remain challenging. In this study, we demonstrate a simple route to recycle gold nanoparticle (Au NP) catalysts by alternating surface wettability. Hydrophilic Au NPs protected with 3-mercapto-1,2-propanediol (MPD) were applied to catalyze the reduction of 4-nitrophenol (4-NP) using sodium borohydride as reductant, and were then separated from the suspension by interfacial ligand exchange with a toluene solution containing triphenylphosphine (TPP), led to amphiphilic Janus Au NPs with both MPD and TPP ligands at the toluene-water interface. The catalyst was regenerated by a reversible ligand exchange with a MPD aqueous solution. Experiments show that interfacial ligand exchange between phosphines and thiols on gold surface is reversible, although the forward and backward rates are different. As a result, the Au NP catalyst capped with MPD exhibited an excellent catalytic activity with an apparent rate constant (k) of 2.79 min−1, and the performance could be maintained for more than 10 regeneration cycles. The facile conversion between hydrophilic and amphiphilic Janus Au NPs provides a new pathway to explore monophasic and multiphasic reactions with convenient catalyst separation and regeneration.

Controlled site coverage of strong metal–support interaction (SMSI) on Pd NP catalysts

The coverage of Pd nanoparticles by SMSI oxides can be controlled with low loadings of TiO(2−x) and by controlling temperature in a reduction, oxidation, and re-reduction process.

Effective perspiration is essential to uphold the stability of zero-gap MEA-based cathodes used in CO2 electrolysers.

The application of gas diffusion electrodes (GDEs) for the electrochemical reduction of CO2 to value-added products creates the possibility of achieving current densities of a few hundred mA cm-2. To achieve stable operation at such high reaction rates remains, however, a challenging task, due to the flooding of the GDE. In order to mitigate flooding in a zero-gap membrane-electrode assembly (MEA) configuration, paths for effective electrolyte perspiration inside the GDE structure have to be kept open during the electrolysis process. Here we demonstrate that apart from the operational parameters of the electrolysis and the structural properties of the supporting gas diffusion layers, also the chemical composition of the applied catalyst inks can play a decisive role in the electrolyte management of GDEs used for CO2 electroreduction. In particular, the presence of excess amounts of polymeric capping agents (used to stabilize the catalyst nanoparticles) can lead to a blockage of micropores, which hinders perspiration and initiates the flooding of the microporous layer. Here we use a novel ICP-MS analysis-based approach to quantitatively monitor the amount of perspired electrolyte that exits a GDE-based CO2 electrolyser, and we show a direct correlation between the break-down of effective perspiration and the appearance of flooding-the latter ultimately leading to a loss of electrolyser stability. We recommend the use of an ultracentrifugation-based approach by which catalyst inks containing no excess amount of polymeric capping agents can be formulated. Using these inks, the stability of electrolyses can be ensured for much longer times.

Ligand-free reductive coupling of aldehydes with 1,3-dienes using a sulfur-modified Au-supported nickel nanoparticle catalyst

Regio- and stereoselective homoallylation reaction of aldehydes with 1,3-dienes using a Ni NP catalyst to afford homoallylated alcohols.

Rational design of ultrafine cobalt free electrospun nanofibers as efficient and durable binfunctional oxygen electrocatalysts for rechargeable zinc-air battery

Rational design of efficient and stable bifunctional oxygen electrocatalyst is of significant importance for research and progress of rechargeable zinc-air battery (ZAB). Herein, ultrafine cobalt free perovskite type oxide Sr2Fe1.5Mo0.5O6-δ nanofibers (SFM NF) and SFM nanoparticles (SFM NP) have been prepared via the electrospinning technique and combustion technique, respectively, and their electrochemical behaviors in the field of ZAB have been studied. Our study demonstrates that SFM NF catalyst has better bifunctional electrocatalytic activities and more durable charge–discharge cycling stability than SFM NP catalyst. When used as cathode catalysts for ZABs, SFM NF electrode exhibits a higher peak power density of 137 mW cm−2 than 107.9 mW cm−2 for SFM NP electrode. In addition, SFM NF electrode presents a lower galvanostatic charge–discharge voltage gap (ΔE) of 0.94 V than 1.13 V for SFM NP electrode when operated at 10 mA cm−2, which can be explained by the enhanced bifunctional electrocatalytic activities. More importantly, SFM NF electrode presents a significantly low ΔE degradation rate of 0.01 V/100 h during the 300-hour operation, indicating its excellent change-discharge stability. Our findings indicate that SFM NF catalyst is a greatly promising cathode candidate of efficient and durable rechargeable ZAB, and the electrospinning technique is an effective strategy to prepare efficient electrocatalysts for energy storage and conversion application.

Synthesis and characterization of BiFeO3/LaFeO3/graphene composites as persulfate activator for removal of 4-nitrophenol

4-Nitrophenol (4-NP) is used to manufacture drugs, fungicides, insecticides, and dyes. Discharge of industrial effluent containing 4-NP into the receiving water could result harmful effects on the environment and human beings. Therefore, in this study advanced oxidation process (AOP) using BiFeO3/LaFeO3/graphene (BFO/LFO/G) composites as catalysts is applied to evaluate the degradation of 4-NP in aqueous solution. LFO/BFO/G was synthesized and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, UV–Vis-diffuse reflectance spectroscopy (DRS), Photoluminesence (PL), Brunauer-Emmett-Teller (BET) surface area analysis, vibrating sample magnetometry (VSM), cyclic voltammetry, thermogravimetric (TGA) analysis and was further used to degrade 4-NP assists with peroxydisulfate (PS) and hydrogen peroxide (H2O2) under UV and visible light irradiation. Each experimental parameter was evaluated, including the initial NP concentration, pH, PS concentrations, and catalyst dosage. Compared to pure BiFeO3, LaFeO3 nanoparticles, and a BiFeO3/LaFeO3 composite, the BiFeO3/LaFeO3/graphene composites significantly increased the degradation of 4-NP. Optimal degradation was achieved with a BiFeO3/LaFeO3/graphene composite containing 5 wt% graphene and could degrade ∼90.2 % of 4-NP within 2 h, with assisted of PS. The degradation of 4-NP in the presence of PS was more efficient under irradiation with visible light than UV light. The dominant mechanism of the degradation process was discussed. Additionally, the LC-MS results proposed the degradation path of 4-NP. Based on the results, the synthesized composites showed their ability to degrade 4-NP in aqueous solutions.

Potential-Driven Restructuring of Cu Single Atoms to Nanoparticles for Boosting the Electrochemical Reduction of Nitrate to Ammonia

Restructuring is ubiquitous in thermocatalysis and of pivotal importance to identify the real active site, yet it is less explored in electrocatalysis. Herein, by using operando X-ray absorption spectroscopy in conjunction with advanced electron microscopy, we reveal the restructuring of the as-synthesized Cu-N4 single-atom site to the nanoparticles of ∼5 nm during the electrochemical reduction of nitrate to ammonia, a green ammonia production route upon combined with the plasma-assisted oxidation of nitrogen. The reduction of Cu2+ to Cu+ and Cu0 and the subsequent aggregation of Cu0 single atoms is found to occur concurrently with the enhancement of the NH3 production rate, both of them are driven by the applied potential switching from 0.00 to -1.00 V versus RHE. The maximum production rate of ammonia reaches 4.5 mg cm-2 h-1 (12.5 molNH3 gCu-1 h-1) with a Faradaic efficiency of 84.7% at -1.00 V versus RHE, outperforming most of the other Cu catalysts reported previously. After electrolysis, the aggregated Cu nanoparticles are reversibly disintegrated into single atoms and then restored to the Cu-N4 structure upon being exposed to an ambient atmosphere, which masks the potential-induced restructuring during the reaction. The synchronous changes of the Cu0 percentage and the ammonia Faradaic efficiency with the applied potential suggests that the Cu nanoparticles are the genuine active sites for nitrate reduction to ammonia, which is corroborated with both the post-deposited Cu NP catalyst and density functional theory calculations.

High-capacity NCNT-encapsulated metal NP catalysts on carbonised loofah with dual-reaction centres over C–M bond bridges for Fenton-like degradation of antibiotics

The intensification of electron transport between the dual-reaction centres in Fenton-like catalyst is demonstrated through the incorporation of carbon-metal (C–M) bond bridges. Herein, nitrogen-doped carbon nanotube-encapsulated Fe3C (Fe3C@NCNT) with dual-reaction centres over short C–Fe bond was constructed through DFT calculation, and accordingly a series of NCNTs-encapsulated Fe/Fe3C, Co, and Mo2C nanoparticles on carbonised loofah were developed by dynamic thermal impregnation and subsequent pyrolysis process. The resultant catalysts displayed satisfactory degradation properties of antibiotics, in which Fe/Fe3C@NCNTs-CL-800 achieved norfloxacin (NOR) removal efficiency of 93.8% in 90 min under neutral pH, and presented excellent cycle stability in NOR removal as well as universality in various antibiotic degradation systems. The remarkable degradation performance of heterogeneous Fenton-like catalysts was attributed to enhancing electron transport to electron-rich M centres over short C–M bond bridges. This study will open a new perspective on the rational design of catalysts for Fenton-like degradation.

One-pot transformation of glucose into hydroxymethyl furfural in water over Pd decorated acidic ZrO2

A high surface acidic ZrO2 nanoparticle was prepared using glucose as a non-toxic reducing agent. Palladium (Pd) nanoparticles in the range of 1–2 nm are grafted in in-situ as well as ex-situ via urea deposition over pre-synthesized ZrO2 nanoparticles. Both methods are found to be useful for the one-pot transformation of glucose to HMF, and their catalytic activities towards selective production of HMF are found to be strongly dependent on the particle size and nature of acidic sites. A linear-type activity trend is observed with Pd loading in reference to the HMF selectivity and presents the best catalytic performance. The activation energy and turnover frequency (TOF) of the 1–2 nm NP catalyst are further calculated to be 44.1 kJ mol−1 and 6.011 molHMF·molPd−1·h−1, respectively. Characterization of the spent catalysts indicates that smaller-sized NPs face severe agglomeration, resulting in poor stability and activity. Hence, the high catalytic performance can be attributed to the balance between Brønsted and Lewis acid sites, in combination with Pd species intrinsic activity. Due to their improved activity and stability, 2Pd–ZrO2in-situ exhibits 55% glucose conversion with 74.0% of HMF selectivity after 3h of reaction at 160 °C.