Bimetallic Pd Research Articles

Synergistic Pd(OAc)2/CuI-catalyzed alkynylation of β-lactam derivative via Sonogashira coupling

Herein, a novel approach of bimetallic Pd(OAc)2/CuI-catalyzed alkynylation of 3-chloroazetidin-2-one (β-lactam derivative) with terminal alkyne via tandem C–C bond activation/Sonogashira-type cross-coupling reaction is developed. This synthesis encompasses a sequence of inert Csp3–X/Csp–H functionalization processes involving the coupling of the C(sp3) adjacent to the 3-chloroazetidin-2-one with the C(sp) of a terminal alkyne. The final analogs are synthesized by means of the indole-benzothiazole Schiff base formation, cyclization of the Schiff base to generate the β-lactam derivative, and Sonogashira coupling to afford a C(sp3)–C(sp) bond. In addition, indole, benzothiazole, and azetidine-2-one have been identified to be highly efficient heterocyclic scaffolds with a range of pharmacological benefits. It encouraged us to discover a hybrid compound that had each of these moieties. Cooperation between two different metals is essential for the successful implementation of this approach. Specifically, the interaction between the Pd and Cu centers in the transmetallation step is depicted through a plausible mechanistic route. The reaction conditions have been optimized by varying catalyst and ligand loadings, bases, temperatures, and solvents. The reaction is highly efficient, yielding alkynylated products in up to 84 % yield with a wide range of substrates and functional group tolerance, thereby serving as a functional model for the Sonogashira coupling reaction.

IMPACT: Innovative (nano)Materials and processes for advanced catalytic technologies to degrade PFOA in water

We hereby report the development of a novel electrochemical method to degrade perfluorooctanoic acid (C7F15COOH, PFOA). At the center of the approach are bimetallic Pd–Ru nano-catalyst materials called IMPACT: Innovative (nano)Materials and Processes for Advanced Catalytic Technologies. IMPACT uses flavonoid-sequestered Pd–Ru, allowing the development of specialized electrodes with tunable properties to sequentially degrade PFOA in wastewater samples into a sustainable byproduct via an indirect electrochemical method. Electron transfers at RuOxHy species stabilize the Pd component of the nano-catalysts, enabling the degradation process via PFOA deprotonation, chain shortening, decarboxylation, hydrolysis, fluoride elimination, and CF2 flake-off mechanism. IMPACT enabled the observation of redox peaks at −0.26 V and 0.56 V for the first time, with accompanying reduction peaks at −0.5V and 0.29 V, respectively. These redox peaks, which correlated with the concentrations of PFOA (20, 50, 100, 200, and 400.mg L−1), were verified and confirmed using electrochemical simulations. Control experiments did not show degradation of PFOA in the absence of Pd–Ru nano-catalyst. The degradation in wastewater was obtained within 3 h with an efficiency of 98.5%. The electrochemical degradation products of PFOA were identified using High-resolution desalting paper spray mass spectrometry (DPS-MS) and collision-induced dissociation (CID) analysis. The results yielded C2F5COOH, C3F7COOH, and C6F13OH with dissociation losses of CF2O or CO2. IMPACT introduces a novel nano-catalyst with high efficiency and a reliable capability that defluorinates strong C–F bonds that are components of recalcitrant organics in myriad environmental matrices.

Nanostructured bi-metallic Pd–Ag alloy films for surface-enhanced Raman spectroscopy-based sensing application

Nanostructured bi-metallic Pd–Ag alloy films for surface-enhanced Raman spectroscopy-based sensing application

Pd‐Pt Bimetallic Catalysts for Enhanced Low‐Temperature Hydrodeoxygenation of Vanillin

AbstractTo make pyrolytic bio‐oil useful as a transportation fuel, the oxygen content must be reduced, and this can be carried out by using catalytic hydrodeoxygenation (HDO) reaction. The greatest challenge is associated with the removal of strongly bound oxygenated groups without saturating the aromatic ring while preserving the number of carbons. However, the development of a stable catalyst that can selectively remove such oxygenated groups with low hydrogen consumption is still challenging. In this context, a systematic study on HDO of vanillin on bimetallic Pd−Pt catalysts was carried out. It aims to study the effect of bimetallic synergy in terms of activity and selectivity to creosol. Metallic nanoparticles of Pd and Pt were synthesized by sol immobilization technique and deposited on TiO2. The conversion of vanillin was correlated to the Pd−Pt atomic ratio, while the production of the creosol was correlated to the Pd(0)/(Pd+Pt) ratio at the surface. Full conversion of vanillin was obtained at low reaction temperature (20 °C) achieving nearly 100 % selectivity to creosol. These results represent a step forward in advancing the development of more efficient and sustainable processes for bio‐oil upgrading.

Bimetallic Au and Pd Nanoparticles Modified WO3 Nanosheets for Enhancing the Sensitivity and Selectivity of Formaldehyde Assessment in Aquatic Products.

Formaldehyde, a common illegal additive in aquatic products, poses a threat to people's health and lives. In this study, a novel metal oxide semiconductor gas sensor based on AuPd-modified WO3 nanosheets (NSs) had been developed for the highly efficient detection of formaldehyde. WO3 NS modified with 2.0% AuPd nanoparticles showed a higher response (Ra/Rg = 94.2) to 50 ppm of formaldehyde at 210 °C, which was 36 times more than the pristine WO3 NS. In addition, the AuPd/WO3 gas sensor had a relatively short response/recovery time of 10 s/9 s for 50 ppm of formaldehyde at 210 °C, with good immunity to other interfering gases and good stability for formaldehyde. The excellent gas-sensitive performance was attributed to the chemical sensitization of Au, the electronic sensitization of Pd, and the synergistic effect of bimetallic AuPd, which facilitated the recognition and response of formaldehyde molecules. Additionally, the high sensitivity and broad application prospect of the 2.0% AuPd/WO3 NS composite-based sensor in real sample detection were also confirmed by using the above sensor for the detection of formaldehyde in aquatic products such as squid and shrimp.

H*ads dynamics engineering via bimetallic Pd–Cu@MXene catalyst for enhanced electrocatalytic hydrodechlorination

Electrocatalytic hydrodechlorination (EHDC) is a promising approach to safely remove halogenated emerging contaminants (HECs) pollutants. However, sluggish production dynamics of adsorbed atomic H (H*ads) limit the applicability of this green process. In this study, bimetallic Pd–Cu@MXene catalysts were synthesized to achieve highly efficient removal of HECs. The alloy electrode (Pd–Cu@MX/CC) exhibited better EHDC performance in comparison to Pd@MX/CC electrode, resulting in diclofenac degradation efficiency of 93.3 ± 0.1%. The characterization analysis revealed that the Pd0/PdII ratio decreased by forming bimetallic Pd–Cu alloy. Density functional theory calculations further demonstrated the electronic configuration modulation of the Pd–Cu@MXene catalysts, optimizing binging energies for H* and thereby facilitating H*ads production and tuning the reduction capability of H*ads. Noteably, the amounts and reduction potential of H*ads for Pd–Cu@MXene catalysts were 1.5 times higher and 0.37 eV lower than those observed for the mono Pd electrode. Hence, the introduction of Cu into the Pd catalyst optimized the dynamics of H*ads production, thereby conferring significant advantages to EHDC reactions. This augmentation was underscored by the successful application of the alloy catalysts supported by MXene in EHDC experiments involving other HECs, which represented a new paradigm for EHDC for efficient recalcitrant pollutant removal by H*ads.

Stepwise carbon dioxide hydrosilylation catalyzed by bimetallic complexes [CpM(CO)2(μ-CO)···Pd([formula omitted])

The interaction of bimetallic (ButPCP)Pd···(OC)M(CO)2 Cp (M = Mo, W) complexes with PhSiH3 leads to an efficient heterolytic splitting of Si–H bond that is a primary step in catalytic hydrosilylation of CO2. The reaction can be stopped at the formate level in the presence of the above complexes while proceeds further when catalyzed by (ButPCP)PdH.

Efficient catalytic oxidation of VOCs by a Pd-Pt/SiO2 catalyst: The cooperative catalysis of dual metal sites

Volatile organic compounds (VOCs) are one of the main pollutants produced in industrial processes. Catalytic oxidation is an effective method to eliminate VOCs, and the key lies in designing efficient metal catalyst. In this work, Pd-Pt/SiO2 bimetallic catalysts were designed and prepared by the immobilization method, and their performances for toluene oxidation were evaluated. The addition of Pt into the catalyst elevated markedly the reduction of Pd active sites, leading to abundant electron-deficient Pd0 and electron-rich Pt0 in the Pd2Pt1 catalyst, which were confirmed by TEM, CO pulse adsorption and in-situ XPS. As revealed by O2-TPD and toluene-TPD characterization, the cooperative effect of electron-deficient Pd0 and electron-rich Pt0 in Pd2Pt1 catalyst facilitated the activation of O2 and toluene, thus enhanced greatly its activity. A conversion of 90% (T90) for toluene was achieved over Pd2Pt1 catalyst at 165 ℃, and the apparent activation energy (Ea) over Pd2Pt1 catalyst was lower than that over other Pd-Pt bimetallic and monometallic Pd or Pt catalysts. Additionally, the reaction mechanism was studied by In-situ DRIFTS, the results showed that the toluene oxidation passed successively benzyl alcohol, benzaldehyde, benzoic acid and maleic anhydride, then maleic anhydride was further oxidized to CO2 and water.

Electrochemical nitrate reduction over bimetallic Pd–Sn nanocatalysts with tunable selectivity toward benign nitrogen

Nitrate is recognized as a highly impactful water contaminant among various pollutants in water. To address the ever-growing demand for water purification, this work investigates the bimetallic palladium (Pd) and tin (Sn) catalysts, which are electrochemically deposited on stainless steel mesh support (Pd–Sn/SS) for the selective conversion of harmful nitrate (NO3−) into benign nitrogen (N2) gas. Results indicate that the bimetallic composition in Pd–Sn/SS electrodes substantially influenced the reaction route for nitrate reduction as well as the performance of nitrate transformation and nitrogen selectivity. It is found that the electrode prepared from Pd:Sn = 1:1 (mole ratio) demonstrates an outstanding nitrate conversion of 95%, nitrogen selectivity of 88%, and nitrogen yield of 82%, which outperform many reported values in the literature. The electrochemically synthesized bimetallic electrode proposed herein enables a new insight for promoting the reactivity and selectivity of nitrate reduction in water.

A bis(PCN) palladium pincer complex with a remarkably planar 2,5-diarylpyrazine core.

A bimetallic Pd complex of a bis(pincer) with a diarylpyrazine core has been prepared. The complex demonstrates near-perfect coplanarity of the aromatic core, is fluorescent under UV irradiation, and displays two quasi-reversible reduction events.

Direct amination of poly(p-phenylene oxide) to substituted anilines over bimetallic Pd–Ru catalysts

We demonstrate a novel route for the upcycling of poly(phenylene oxide) (PPO) into dimethylanilines using a bimetallic Pd7Ru3/CNT catalyst. This represents the first successful transformation of PPO into nitrogen-containing compounds.

Supercritical deposition of mono- and bimetallic Pd and Pt on TiO[formula omitted] coated additively manufactured substrates for the application in the direct synthesis of hydrogen peroxide

In this study we investigated the properties of mono- and bimetallic Pd and Pt deposited via supercritical fluid reactive deposition (SFRD) on TiO2 coated additively manufactured substrates. The focus of this work lies on the suitability of these catalysts for the direct synthesis of H2O2 in the liquid phase. All catalysts produced showed a high activity towards the desired reaction, derived from high productivities towards the desired product. Thereby, the productivity of the different catalysts decreased in the following order: Pd = PdPt > Pt. In agreement with literature, an increase of the Pd loading from 1 to 2 wt.-% led to a decrease in the productivity. Resulting from comparison with productivities from literature, this method indicates a high suitability of the SFRD method for the suggested application. Due to the easy and eco-friendly nature of this deposition method the catalyst production process can be intensified.

Bimetallic Pd–Co Aerogel Three-Dimensional Architecture: Developing Self-Assembled Materials for Advanced Ethanol Oxidation

Bimetallic Pd–Co Aerogel Three-Dimensional Architecture: Developing Self-Assembled Materials for Advanced Ethanol Oxidation

Green Hydrogenation of C=C, C=O, and C=N Bonds in Water by Palladium‐Tin Bimetallic Nanoparticles

AbstractThe reduction of various functional groups under atmospheric H2 by Pd−Sn nanoparticles in water is reported. A broad set of C−C, C−O, and C−N multiple bonds were reduced using a catalyst loading of 0.56 mol % to give rise to a high yield of products up to 99 % and good tolerance with various substrates. Additionally, the bimetallic Pd−Sn system successively hydrogenated the olefinic double bond of α,β‐unsaturated carbonyl compounds with selectivity up to 99 % demonstrating further its chemoselectivity. The catalyst is recyclable for up to five cycles with α‐methyl styrene as the substrate. However, with functionalized alkenes such as acrylic acid, the recyclability was poor.

Pd+Al2O3-Supported Ni-Co Bimetallic Catalyst for H2 Production through Dry Reforming of Methane: Effect of Carbon Deposition over Active Sites

Dry reforming of methane (DRM) is gaining global attention due to its capacity to convert two greenhouse gases together. It proceeds through CH4 decomposition over active sites (into CH4−x) followed by CH4−x oxidation by CO2 (into syngas). Furthermore, CH4−x oligomerization into coke cannot be neglected. Herein, xNi(5−x)Co/Pd+Al2O3 (x = 5, 3.75, 2.5, 1.25, 0) catalysts are prepared, investigated for DRM, and characterized with X-ray diffraction, UV-Vis, transmission electron microscopy, temperature-programmed reduction/desorption techniques, and thermogravimetry. Fine-tuning among stable active sites, graphitic carbon deposits, and catalytic activity is noticed. The total reducibility and basicity are found to decrease upon increasing the Co proportion up to 2.5 wt% in the Ni-Co bimetallic Pd+Al2O3-supported catalyst. The active sites derived from strong metal–support interaction species (NiAl2Ox or dispersed CoOx) are found to be promising in higher levels of activity. However, activity is, again, limited by graphitic carbon which is increased with an increasing Co proportion in the Ni-Co bimetallic Pd+Al2O3-supported catalyst. The incorporation of 1.25 wt% Co along with 3.75 wt% Ni over Pd+Al2O3 results in the generation of fewer such active sites, extensive oxidizable carbon deposits, and inferior catalytic activity compared to 5Ni/Pd+Al2O3. The 2.5Ni2.5Co/Pd+Al2O3 catalyst has lower crystallinity, a relatively lower coke deposit (than the 3.75Ni1.25Co/Pd+Al2O3 catalyst), and a higher number of stable active sites. It attains a 54–51% H2 yield in 430 min TOS and 0.87 H2/CO (similar to 5Ni/Pd+Al2O3)

SYNERGETIC EFFECTS OF PALLADIUM(II) AND COPPER(II) COMPOUNDS FIXED ON MODIFIED PHLOGOPITE IN THE REACTION WITH SULFUR DIOXIDE

Palladium(II) and cuprum(II) compounds are the basic components of the Wacker-type heterogeneous catalyst for the low-temperature oxidation of carbon monoxide with oxygen. Al2O3, activated carbon and carbon fiber materials are most commonly used as a carrier. In search of new potential natural media, layered aluminosilicate – phlogopite as part of natural phlogopite concentrate was investigated and it was proved that copper-palladium catalysts are formed on acid-modified samples of phlogopite, which provide a high degree of conversion of carbon monoxide, which meets the sanitary and chemical norm of CO in the working area, namely CKCO ≤ 20 mg/m3. Regardless of the nature of the carrier, it was found that the catalytic effect is achieved due to the synergism of palladium(II) and copper(II). A typical situation is when carbon monoxide and sulfur dioxide are simultaneously present in the waste gases of industrial enterprises. In this regard, research on the polyfunctionality of the Pd(II)-Cu(II)/S̅ nanocatalyst is relevant. The kinetics of the interaction of sulfur dioxide with mono- and bimetallic compositions based on compounds of palladium(II), copper(II) and acid-modified natural (Phl) and thermally swollen (TS-Phl) phlogopite were studied. It was established that monometallic compositions М(ІІ)-KBr/X̅Н-TC-Phl-1, М(ІІ) = Cu(ІІ), Pd(ІІ) fixed on acid-modified samples of swollen phlogopite, except for 6Н-TS-Phl-1, do not show protective properties against sulfur dioxide. It has been proven that the bimetallic compositions Pd(II)-Cu(II)-KBr/S̅ (S̅ = 6H-Phl-1; X̅H-TS-Phl-1, X̅ = 1, 2, 3, 6 M HNO3) in the reaction with SO2 reveal a synergistic effect with a coefficient of КS >> 1, which leads to an increase in the time of the protective action of the samples and the amount of absorbed sulfur dioxide. The synergism constant depends on the conditions of acid modification of the carrier and has a maximum value in the case of the bimetallic composition fixed on the carrier 2Н-ТS-Phl-1.

Green synthesis of bimetallic Pd[sbnd]Ag alloy nanoparticles supported on polydopamine-functionalized kaolin for catalytic reduction of 4-nitrophenol and organic dyes

A green and universal synthesis strategy was demonstrated for preparation of bimetallic PdAg alloy nanoparticles supported on polydopamine-functionalized kaolin (kaolin-PDA-PdAg), where bimetallic PdAg alloy was synthesized by co-reduction of Na2PdCl4 and AgNO3 with sodium citrate. Characterization results, including TEM results and XPS results, confirmed that bimetallic PdAg was alloying state and kaolin-PDA-PdAg was successfully synthesized through mussel-inspired chemistry. The kaolin-PDA-PdAg nanocomposite exhibited excellent catalytic activity and performance towards reduction of 4-nitrophenol, whose rate constant was found to be 3.46 min−1 under condition of high concentration (10 mM) of 4-nitrophenol. Besides, kaolin-PDA-PdAg nanocomposite showed high catalytic performance for methyl orange and safranine-T as well. The high catalytic activity of kaolin-PDA-PdAg could be elucidated by electronic effect and synergistic effect of bimetallic PdAg alloy. These results suggest that kaolin-PDA-PdAg composites could be applied as high-efficiency catalysts for reduction of 4-nitrophenol and degradation of organic dyes. Furthermore, abundance and low-priced of raw materials kaolin, green and versatility of synthetic method endow kaolin-PDA-PdAg composites with broad application prospects. Strategy of bimetallic PdAg alloy anchored on kaolin in this text could provide an efficient platform for synthesis of bimetallic alloy nanoparticles loaded on various materials.

Formic Acid Dehydrogenation over a Monometallic Pd and Bimetallic Pd:Co Catalyst Supported on Activated Carbon

In this study, palladium is proposed as an active site for formic acid dehydrogenation reaction. Pd activity was modulated with Co metal with the final aim of finding a synergistic effect that makes possible efficient hydrogen production for a low noble metal content. For the monometallic catalysts, the metal loadings were optimized, and the increase in the reaction temperature and presence of additives were carefully considered. The present study aimed, to a great extent, to enlighten the possible routes for decreasing noble metal loading in view of the better sustainability of hydrogen production from liquid organic carrier molecules, such as formic acid.

Hydrogen-Treated TiO2 Nanorods Decorated with Bimetallic Pd–Co Nanoparticles for Photocatalytic Degradation of Organic Pollutants and Bacterial Inactivation

Herein, first, we synthesize a multifunctional photocatalyst via metal oxides loaded (Co/Pd) on acid-treated TiO2 nanorods (ATO) and further introduce hydrogen annealing treatment. The hydrogen annealing treatment introduces metal oxides converted into a bimetallic form and delays the photogenerated charge recombination process. Also, oxygen vacancies are formed due to the partial reduction of Ti4+ to Ti3+ sites. In addition, oxygen vacancies help to improve photocatalytic degradation and antibacterial activity. The hydrogen-treated photocatalyst (Pd(1)Co(1)/ATO (red)) demonstrates high degradation efficiencies of 99.63 and 99.90% (180 min) for orange II dye and BPA degradation, respectively, and an antibacterial activity of 97.00% (120 min) under one sun irradiation. In the photocatalytic removal of abiotic pollutants and live bacteria, the trapping experiment suggests that radical species (•O2– and •OH), assisted by photoinduced holes, are responsible for the high activities. The photoelectrochemical performance and time-resolved PL (TRPL) study illustrate that Pd(1)Co(1)/ATO (red) reveals superior photoelectrochemical charge separation (electron–hole), lower resistance, and shorter lifetime (τ1 = 0.40 ns) as a photocatalyst. Finally, plausible charge transport mechanisms are proposed for the photocatalytic degradation of organic dye and bacterial disinfection over the Pd(1)Co(1)/ATO (red) photocatalyst.

Hierarchical Flower-like WO3 Nanospheres Decorated with Bimetallic Au and Pd for Highly Sensitive and Selective Detection of 3-Hydroxy-2-butanone Biomarker.

Listeria monocytogenes, which is abundant in environment, can lead to many kinds of serious illnesses and even death. Nowadays, indirectly detecting the metabolite biomarker of L. monocytogenes, 3-hydroxy-2-butanone, has been verified to be an effective way to evaluate the contamination of L. monocytogenes. However, this detection approach is still limited by sensitivity, selectivity, and ppb-level detection limit. Herein, low-cost and highly sensitive and selective 3-hydroxy-2-butanone sensors have been proposed based on the bimetallic AuPd decorated hierarchical flower-like WO3 nanospheres. Notably, the 1.0 wt % AuPd-WO3 based sensors displayed the highest sensitivity (Ra/Rg = 84 @ 1 ppm) at 250 °C. In addition, the sensors showed outstanding selectivity, rapid response/recovery (8/4 s @ 10 ppm), and low detection limit (100 ppb). Furthermore, the evaluation of L. monocytogenes with high sensitivity and specificity has been achieved using 1.0 wt % AuPd-WO3 based sensors. Such a marvelous sensing performance benefits from the synergistic effect of bimetallic AuPd nanoparticles, which lead to thicker electron depletion layer and increased adsorbed oxygen species. Meanwhile, the unique hierarchical nanostructure of the flower-like WO3 nanospheres benefits the gas-sensing performance. The AuPd-WO3 nanosphere-based sensors exhibit a particular and highly selective method to detect 3-hydroxy-2-butanone, foreseeing a feasible route for the rapid and nondestructive evaluation of foodborne pathogens.