Palladium Oxide Nanoparticles Research Articles

Nitrogen-doped carbon microfibers decorated with palladium and palladium oxide nanoparticles for high-concentration hydrogen sensing

Hydrogen (H2) sensing materials with tuned geometrical shapes and dopants may contribute to H2 sensing performance, however, their synthetic approaches need further exploring. Here, shape-controlled nitrogen-doped carbon microfibers decorated with palladium and palladium oxide nanoparticles (Pd/PdO NPs@C/N MFs) have been prepared by combined electrospinning, annealing and chemical deposition. Typically, the C/N MFs of ∼224 nm in diameter are observed with amorphous crystallization, around which the Pd/PdO NPs (∼20 nm in diameter) are randomly decorated. Beneficially, Pd/PdO NPs@C/N MFs present high-concentration sensing toward 0.01–30 v/v% H2 at room temperature. Theoretically, the nitrogen dopants in PVP contribute to anchoring the growth of Pd/PdO NPs, leading to stable decoration on the surface of MFs. The excellent sensing performance might be interpreted as the synergistic effect that Pd/PdO NPs@C/N MFs expose more adsorption sites, Pd adsorbs H2 to form PdHx intermediates, PdO alters the electronic state of Pd to assist the adsorption of H2, and C/N MFs serve as the support and boost the electron transfer. Practically, the simulation utilizing Pd/PdO NPs@C/N MFs to detect H2 leakage has been conducted with reliable sensing.

Mesoporous PdO–loaded WO3 nanocrystals: A promising photocatalyst for highly efficient photoreduction of nitrobenzene to aniline under visible light

BackgroundNitrobenzene (NTB) conversion to aniline (AN) is a key technology for large-scale industrial chemical production and wastewater treatment. Accordingly, photocatalytic reduction of nitrobenzene has emerged as a green technology to produce aniline. MethodsThis study offers a simple nontoxic surfactant-assisted fabrication of mesoporous tungsten oxide (WO3) nanostructures accompanied by the incorporation of tiny contents (0.5‒2.0 wt%) of palladium oxide (PdO) nanoparticles through impregnation and calcination. Significant findingsPhysicochemical investigations of fabricated heterostructures revealed the formation of mesoporous surfaces and showed the implication of PdO loading on textural and optoelectronic characteristics of WO3. Only 2.0 wt% PdO on the WO3 surface caused a notable decline in the energy bandgap from 2.77 to 1.07 eV, confirming visible light-harvesting improvement. The prepared PdO–loaded WO3 was examined for NTB photoreduction to AN. The optimum content of 1.5 wt% PdO/WO3 (2.0 g L–1) exhibited a complete phototransformation of NTB to AN after only 40 min with excellent reusability and recyclability. The PdO loading significantly facilitated photoinduced charge carriers’ separation and mobility through the construction of Step (S)-scheme heterojunction. This work opens the door for developing semiconductor-based photocatalysis as a green process for effectively converting contaminated water into useful value-added chemicals.

Selective Deposition of PdO Nanoparticles on Si Nanodevices for Hydrogen Sensing

In this paper, we present a method, involving plasma-enhanced atomic layer deposition and constant-power device-localized Joule heating (DLJH), for the selective deposition of palladium oxide (PdO) nanoparticles at the n– region of n+/n–/n+ polysilicon nanobelt (PNB) devices. These PdO-decorated PNB devices were then operated under DLJH so that the temperature of the n– region was maintained during the sensing of H2 gas. From their measured responses, the devices operated at a temperature of 339 K exhibited the most reactive interactions between PdO and H2. Considering the possibility of humidity interference, we also characterized the PdO-decorated PNB devices for H2 sensing at various relative humidities. The PdO nanoparticles on the PNB devices having a grain distance that sustained a spillover effect were almost immune to RH interference.

PdO-Nanoparticle-Embedded Carbon Nanotube Yarns for Wearable Hydrogen Gas Sensing Platforms with Fast and Sensitive Responses

Hydrogen (H2) gas has recently become a crucial energy source and an imperative energy vector, emerging as a powerful next-generation solution for fuel cells and biomedical, transportation, and household applications. With increasing interest in H2, safety concerns regarding personal injuries from its flammability and explosion at high concentrations (>4%) have inspired the development of wearable pre-emptive gas monitoring platforms that can operate on curved and jointed parts of the human body. In this study, a yarn-type hydrogen gas sensing platform (HGSP) was developed by biscrolling of palladium oxide nanoparticles (PdO NPs) and spinnable carbon nanotube (CNT) buckypapers. Because of the high loading of H2-active PdO NPs (up to 97.7 wt %), when exposed to a flammable H2 concentration (4 vol %), the biscrolled HGSP yarn exhibits a short response time of 2 s, with a high sensitivity of 1198% (defined as ΔG/G0 × 100%). Interestingly, during the reduction of PdO to Pd by H2 gas, the HGSP yarn experienced a decrease in diameter and corresponding volume contraction. These excellent sensing performances suggest that the fabricated HGSP yarn could be applied to a wearable gas monitoring platform for real-time detection of H2 gas leakage even over the bends of joints.

Ultrasound assisted synthesis of attapulgite-PdO nanocomposite using palladium complex for hydrogen storage: Kinetic studies

• 3,4,5-trimethoxybenzoic acid was used to synthesis new palladium complexes in the presence of triphenylephosphine as mixed ligand ([Pd(TMB) 2 (Pph 3 ) 2 ]). • [Pd(TMB) 2 (Pph 3 ) 2 ] was used as a palladium precursor for the ultrasound synthesis of attapulgite-PdO nanocomposite. • Attapulgite-PdO nanocomposite was used for hydrogen storage application with a maximum storage of 3.81 wt%. This research included the synthesis and characterization of new complex by in-situ method using two mole equivalent from 3,4,5-trimethoxybenzoic acid (TMB) and triphenylphosphine (Pph 3 ) in the presence of triethylamine (NEt 3 ). This complex was characterized using FTIR, 1 H NMR, 31 P NMR, CHN, molar conductivity. The results prove that TMB ligand behave as monodentate through the protonated oxygen atom of the carboxylic. This complex was used as a precursor for the synthesis of PdO@attapulgite nanocomposite which was characterized using TEM and XRD. The measurement proved that the palladium oxide nanoparticles had a positive effect in reducing the diameter of the attapulgite channels from 160 nm to the range 90–95 nm. This nanocomposite was used as a potential material for hydrogen storage. The results of hydrogen storage showed that the composite has the ability to store hydrogen even at low pressures, as it was noted that the composite had the ability to store approximately 1 wt% at 30 bar and reached 3.81 wt% at 90 bar. The kinetic studies prove that the storage fit to the pseudo-second order with coefficient factor equal to 0.9278 and the hydrogen storage was reached the maximum (3.81 wt%) after only 200 s.

Ultrasound-assisted green synthesis of Urchin like palladium oxide nanoparticles using alginate and its photocatalytic application

• Ultrasound assisted synthesis of urchin like PdO-NPs using sodium alginate was suggested. • The formed PdO-NPs were characterized by UV–vis, TEM, DLS, XRD, and FTIR. • The prepared PdO-NPs exhibited photocatalytic degradation of methylene blue dye (10 mg/L, k = 2.082 × 10 -3 min -1 ). In this investigation we studied the potential of ultrasound for the production of urchin like palladium oxide nanoparticles (PdO-NPs) using sodium alginate and further photocatalytic activity is evaluated. The formation of as-synthesized PdO-NPs was characterized by various physicochemical techniques. The surface plasmon resonance band observed in UV–Vis spectroscopy initially indicated the formation of PdO-NPs. Dynamic light scattering, high-resolution transmission electron microscope, selected area electron diffraction pattern, X-ray powder diffraction and infrared spectroscopy were used to confirm the uniform spherical-urchin shapes and high crystallinity of PdO-NPs with particle size of 60–70 nm. The synthesized PdO-NPs can be used as a heterogeneous catalyst in the photocatalytic degradation of methylene blue (10 mg/L, k 4 = 2.082 × 10 -3 min -1 ) under direct sunlight. Our protocol for the ultrasound-assisted synthesis of PdO-NPs offers a new means to develop environmentally benign nanoparticles for the environmental remediation.

Facile deposition of palladium oxide (PdO) nanoparticles on CoNi2S4 microstructures towards enhanced oxygen evolution reaction

Strong demand for renewable energy resources and clean environments have inspired scientists and researchers across the globe to carry out research activities on energy provision, conversion, and storage devices. In this context, development of outperform, stable, and durable electrocatalysts has been identified as one of the major objectives for oxygen evolution reaction (OER). Herein, we offer facile approach for the deposition of few palladium oxide (PdO) nanoparticles on the cobalt–nickel bi-metallic sulphide (CoNi2S4) microstructures represented as PdO@ CoNi2S4 using ultraviolet light (UV) reduction method. The morphology, crystalline structure, and chemical composition of the as-prepared PdO@ CoNi2S4 composite were probed through scanning electron microscopy, powder x-ray diffraction, high resolution transmission electron microscopy, energy dispersive spectroscopy and x-ray photoelectron spectroscopy techniques. The combined physical characterization results revealed that ultraviolet light (UV) light promoted the facile deposition of PdO nanoparticles of 10 nm size onto the CoNi2S4 and the fabricated PdO@ CoNi2S4 composite has a remarkable activity towards OER in alkaline media. Significantly, it exhibited a low onset potential of 1.41 V versus reversible hydrogen electrode (RHE) and a low overpotential of 230 mV at 10 mA cm−2. Additionally, the fabricated PdO@ CoNi2S4 composite has a marked stability of 45 h. Electrochemical impedance spectroscopy has shown that the PdO@CoNi2S4 composite has a low charge transfer resistance of 86.3 Ohms, which favours the OER kinetics. The PdO@ CoNi2S4 composite provided the multiple number of active sites, which favoured the enhanced OER activity. Taken together, this new class of material could be utilized in energy conversion and storage as well as sensing applications.

PdO and PtO loaded WS2 boosts NO2 gas sensing characteristics at room temperature

In this work tungsten disulphide nanostructures loaded with platinum-oxide (PtO), or palladium-oxide (PdO) were grown directly onto alumina substrates. This was achieved using a combination of aerosol-assisted chemical vapour deposition (AA-CVD) method with atmospheric pressure CVD technique. At first, tungsten oxide nanowires loaded with either PtO or PdO nanoparticles were successfully co-deposited via AA-CVD followed by sulfurization at 900 °C in the next step. The morphological, structural, and chemical characteristics were investigated using FESEM, TEM, XRD, XPS and Raman spectroscopy. The results confirm the presence of PdO and PtO in the WS2 host matrix. Gas sensing attributes of loaded and pristine WS2 sensors were investigated, at room temperature, towards different analytes (NO2, NH3, H2 etc.). Both pristine and metal-oxide loaded WS2 gas sensors show remarkable responses at room temperature towards NO2 detection. Further, the loaded sensors demonstrated stable, reproducible, ultrasensitive, and enhanced gas sensing response, with a detection limit below 25 ppb. Additionally, the effect of ambient humidity on the sensing response of both loaded and pristine sensors was investigated for NO2 gas. The response of PtO loaded sensor considerably decreased in humid environments, while the response for pristine and PdO loaded sensors increased. However, slightly heating (at 100 °C) the sensors, suppresses the influence of humidity. Finally, the long-term stability of different sensors is investigated, and the results demonstrate high stability with repeatable results after 6 weeks of gas sensing tests. This work exploits an attractive pathway to add functionality in the transition metal dichalcogenide host matrix.

Suzuki–Miyaura Cross-Coupling on Polystyrene-Supported Palladium Oxide Nanoparticles in Water

Key words Suzuki–Miyaura cross-coupling - palladium catalysis - nanoparticles - aryltrifluoroborates - aqueous media

Gamma Alumina Supported Zinc Oxide Promoted with Ruthenium Oxide (Ruo2-Zno/Al2o3) and Palladium Oxide Nanoparticles (Pdo-Zno/Al2o3): Efficient Electrocatalysts for Hydrazine Oxidation Reaction (Hzor)

Gamma Alumina Supported Zinc Oxide Promoted with Ruthenium Oxide (Ruo2-Zno/Al2o3) and Palladium Oxide Nanoparticles (Pdo-Zno/Al2o3): Efficient Electrocatalysts for Hydrazine Oxidation Reaction (Hzor)

Diamine-functionalized porous graphene oxide sheets decorated with palladium oxide nanoparticles for the oxidative amidation of aldehydes

C–N coupling between aldehydes and amines by ultra-small PdO NPs adorned diamine functionalized porous GO sheets as retrievable nano-catalyst.

Supported palladium oxide nanoparticles in Al-SBA-15 as an efficient and reusable catalyst for the synthesis of pyranopyrazole and benzylpyrazolyl coumarin derivatives via multicomponent reactions

Supported palladium oxide nanoparticles in Al-SBA-15 as an efficient and reusable catalyst for the synthesis of pyranopyrazole and benzylpyrazolyl coumarin derivatives via multicomponent reactions

An efficient palladium oxide nanoparticles@Co3O4 nanocomposite with low chemisorbed species for enhanced oxygen evolution reaction

Significant progress has been made in recent time to design and synthesize highly efficient and cost effective electrocatalysts for oxygen evolution reaction (OER). However, the electrocatalytic activity of most recently reported materials is limited by the large onset potential, poor electrical conductivity and low density of catalytic centers. In this study, we report facile deposition of palladium oxide nanoparticles onto cobalt oxide nanostructures (PdONPs@Co3O4) through the illumination of ultraviolet (UV) light. The fabricated PdONPs@Co3O4 nanocomposites offer high density of active sites, improved electrical conductivity and durability for OER activity. The synergetic effect between the Co and Pd ions at the interface of composite system might change the adsorption energy of reaction intermediates, thus enabled the reaction to proceed at lower energy consumption. Significantly, the prepared PdONPs@Co3O4 samples demonstrated a low overpotential of 250 mV at a current density of 20 mA/cm2, with low charge transfer resistant of 48.5 Ωand high durability for more than 40 h during OER processes. The combined results suggest that incorporating of a low amount of PdONPs can tune the surface properties of Co3O4 and interfacial chemistry. This could led to accelerate the charge transport properties at the interface during a specific electrochemical application.

Pd‐Au Supported Reduced Graphene Oxide Catalyst for Carbon‐ Hydrogen Bond Activation in Benzene

AbstractAn improved reduced graphene oxide supported bimetallic palladium and gold catalyst was synthesized for the carbon‐hydrogen bond activation of un‐activated aromatic organic substrate benzene. XPS analysis has revealed that catalyst contained Au(0) nanoparticles with Pd(II) ions on its surface. The surface of rGO was found to be rich in sp2 carbon content with >C=O groups that most probably provided supporting sites for the gold and palladium metals. The XRD analysis further confirmed that Au(0) nanoparticles with palladium oxide and palladium nanoparticles were present on rGO surface. The catalytic activity of the material was tested towards activation of benzene to form biphenyl as an end product. Density function theory has revealed that Pd(II) ion was the active component that insert itself in between C−H bond of benzene and showed efficiency to interact with oxygen molecules. Simultaneously, Au(0) atoms have the tendency to adsorb on the π‐bonded surface of the catalyst and extend its conjugation that reduced the HOMO‐LUMO gap of the catalyst and provided the good catalytic activity.

Hampered PdO Redox Dynamics by Water Suppresses Lean Methane Oxidation over Realistic Palladium Catalysts

AbstractBy use of operando spectroscopies under cycling reaction conditions, water is shown to hamper the redox dynamics of realistic palladium oxide nanoparticles dispersed onto alumina and hydrophobic zeolite supports thereby lowering the activity for total oxidation of methane. Water adsorption forms hydroxyl ad‐species that block the methane and oxygen dissociation and seem to prevent lattice oxygen to take part in the methane oxidation. The main catalytic action is thus proposed to shift from the Mars‐van Krevelen mechanism in dry conditions to a slower route that relies on Langmuir‐Hinshelwood type of steps in wet conditions. This key finding has clear implications on catalyst design for low‐temperature gas combustion emission control.

Enhanced photocatalytic performance of PdO-loaded heterostructured nanobelts to degrade phenol

Heterostructured catalysts play a significant role in the photodegradation of pollutants in wastewater. Combining the large surface of nanobelts with the high photocatalytic property of titanium dioxide (TiO2) nanoparticles is a promising method for preparing photocatalysts, which have an advanced photocatalytic activity and are easy to precipitate. In this work, titanium dioxide nanobelts (NB) and acid corroded titanium dioxide nanobelts (C-NB) were synthesized via a hydrothermal process under alkaline conditions. Their surfaces were then loaded with palladium oxide (PdO) nanoparticles to prepare heterostructured photocatalysts (PdO-NB and PdO-C-NB) by a well-designed chemical precipitation method. The photodegradation efficiencies of the four catalysts for phenol, as well as for methyl orange, were tested and the order of degradation efficiency was found to be PdO-C-NB > PdO-NB > C-NB > NB. A degradation efficiency of 61% for phenol was achieved within 90 min using PdO-C-NB, which was nearly twice as much as using NB. The enhanced photocatalytic property of PdO-C-NB was due to the large specific surface area, abundant photocatalytic active sites and the low recombination rate of electron-hole pairs. Therefore, the degradation of phenol and methyl orange was speeded up considerably. Considering the high catalytic activity of PdO-C-NB, the heterostructure catalyst is of great significance to the degradation of organic wastewater, and has an important impact on our ecological environment and human health.

The first PdO nanoparticle catalyzed one pot synthesis of propargylamine through A3-coupling of an aldehyde, alkyne and amine

Palladium(ii) oxide (PdO) nanoparticles (Nps) were prepared by an environmentally benign hydrothermal method with a new capping agent quercetin.

PdO Nanoparticles Supported on MnO2 Nanowire Aerogels as Catalysts for Low-Temperature Methane Combustion

Palladium oxide nanoparticles were loaded onto a nanostructured MnO2 aerogel by a deposition–precipitation method. The resulting nanomaterial exhibited excellent catalytic activity for low-temperat...

Preparation of palladium oxide nanoparticles supported on tin oxide nanofibers via modified electrospinning for ultra-low ppb NO2 detection

Herein, we describe the fabrication of a gas sensor based on self ordered SnOx nanofibers decorated with PdOx nanoparticles by using a simple, flexible and scalable approach. The sensing material was synthesized and integrated onto screen printed microceramic platform using modified electrospinning. Material morphology and structure were addressed by Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM) and X-Ray Diffraction analysis (XRD). Moreover, X-ray Photoelectron Spectroscopy (XPS) confirmed the successful grafting of palladium ions onto the nanofiber outer wall.In an attempt to fully replicate the real working conditions of a gas sensor, the electrical measurements were performed upon exposure of the sensor to different concentrations of NO2 diluted in humid air. PdOx@SnOx sensor demonstrated a remarkable sensitivity towards NO2 with good linearity and detection limit around 10 ppb under humid air. Furthermore, the sensor exhibited an ultra weak cross sensitivity towards interfering air pollutants present at high ppm level such as CO and NH3 at 325 °C. For comparison, the reference sensor based on bare SnOx showed a degraded response towards tested gases under humid ambient. This proves the potential of the hybrid sensor preparation protocol regarding its future application for the detection and quantification of low levels of NO2 in air.

Wearable colorimetric sensing fiber based on polyacrylonitrile with PdO@ZnO hybrids for the application of detecting H2 leakage

A colorimetric hydrogen sensor has great potential for accurately detecting and monitoring the leakage of hydrogen gas on account of its fast color change in contact with hydrogen gas. However, for the practical application of the sensor, such as in gas detection systems in clothing, the flexibility and stability of the sensor need to be improved. Here, we present a novel method to fabricate a flexible colorimetric hydrogen sensor with the stable embedment of sensing material. To improve the flexibility and stability of the sensor, polyacrylonitrile nanofiber containing palladium oxide and zinc oxide hybrid nanoparticles was prepared by electrospinning. The flexible colorimetric hydrogen sensor can detect 1000 ppm hydrogen gas with excellent selectivity within 2 min. We also suggest film and yarn-type flexible colorimetric hydrogen sensors for industrial and wearable applications. A laminating process was used to prepare the film. In contrast, twisting and polydimethylsiloxane coating were used to prepare the yarn-type flexible colorimetric hydrogen sensor. Compared with a flexible colorimetric hydrogen-sensing nanofiber, the film and yarn show identical sensitivity for detecting a hydrogen leakage. These applications of hydrogen sensors could be a new insight into the design of a flexible sensor for detecting hydrogen leakage with the naked eye.