PdCl2 Solution Research Articles

Electroless Deposition of Noble Metals on Rod-Shape Plant Viruses in Various Aqueous Metal Precursor Solutions.

The challenge of synthesizing noble metal nanostructures sustainably has encouraged researchers to explore biological routes for nanostructure production, such as biotemplating. Plant viruses with rod-shape morphology, such as tobacco mosaic virus (TMV) and barley stripe mosaic virus (BSMV), offer promising biotemplates to produce metal nanorods. TMV and BSMV can be incubated in aqueous metal precursor solutions to mineralize metals on the coat proteins (CPs) of the viruses. Previous studies have primarily examined palladium (Pd) mineralization on TMV and BSMV using Na2PdCl4 as the Pd precursor. There is limited scientific literature on the effect of using alternative Pd precursor solutions besides Na2PdCl4 such as K2PdCl4 and PdCl2 to mineralize Pd on TMV and BSMV. Past attempts at mineralizing other noble metals such as platinum (Pt) and gold (Au) required an initial layer of Pd to be deposited on the TMV and BSMV biotemplates. In this study, we aimed to expand the understanding of using alternative Pd precursor solutions to mineralize Pd on TMV and BSMV. Additionally, the deposition of Pt and Au onto TMV and BSMV without the need for an initial Pd mineralization layer was achieved using alternative Pt and Au precursors, including K2PtCl4 and AuCl3, respectively. Pd, Pt, and Au were successfully deposited on TMV and BSMV by incubation in aqueous solutions of Na2PdCl4, K2PdCl4, PdCl2, K2PtCl4, and AuCl3. Kinetic studies were also conducted using ultraviolet-visible (UV-vis) spectroscopy to examine the rates at which Pd, Pt, and Au precursor ions were reduced during the mineralization process, mimicking their adsorption onto TMV and BSMV CPs. BSMV adsorbed noble metal precursor ions faster than TMV as determined by UV-vis spectroscopy. While palladium nanorods (PdNRs) offer high electrical conductivity desirable for electronic applications, Pd-coated TMV and BSMV may face limitations due to their organic cores, potentially compromising conductivity. To address this, one approach is to convert the organic core into conductive amorphous carbon through thermal annealing. In this study, in situ transmission electron microscopy was utilized to thermally anneal Pd-TMV2Cys, thereby transforming them into PdNRs with amorphous carbon cores.

Uniformly Distributed Palladium Nanoparticles on NH2‐MIL‐53 Fabricated by an Equilibrium Adsorption Method for Reduction of Nitrite in Water

Metal particle on a support material should be small and homogeneous in size, which is desirable when using it as a catalyst. In this study, we investigated to introduce Pd nanoparticles (NPs) with narrow size distribution into NH2‐MIL‐53, which was prepared by the reaction of aluminum(III) nitrate with 2‐aminoterephthalic acid. Only by immersing it in an aqueous PdCl2 solution, followed by the reduction with NaBH4, Pd NPs of about 2 nm with unform distribution were formed in NH2‐MIL‐53 up to 3.5 wt.% Pd loadings. Amino group on the linkers in NH2‐MIL‐53 played a critical role for the introduction of (PdCl3)– as a precursor for Pd NPs, while no Pd was introduced into MIL‐53 without amino group. The obtained catalysts (Pd@NH2‐MIL‐53) showed high catalytic performance for reduction of nitrite in water. The specific activity per Pd site exposed on the surface changed greatly depending on the Pd loadings despite the size of Pd NPs unchanged. Pd@NH2‐MIL‐53 with low Pd loadings showed higher specific activity (TOF = 2.9×102 h‐1), which might be due to the preferential exposure of Pd(111) facet on Pd NPs.

Synthesis, characterization and catalytic activities of palladium(II)-imidazopyridine

The ligand 2-phenylimidazo(1,2-α)pyridine (1) was synthesized by neat reaction 2-aminopyridine and 1-bromo-acetophenone; reaction of 1 with acetonitrile solution of PdCl2 leads to [Pd(1)Cl2(CH3CN)] (2). Refluxing [Pd(1)Cl2(CH3CN)] (2) in pyridine leads to [Pd(1)Cl2(py)] (3).The complexes were characterized by various spectroscopic techniques and the solid state structure of 2 was elucidated by single crystal X-ray diffraction (SCXRD) analyses. SCXRD analyses support the square planar geometry of 2. A series of DFT calculations were also performed to gain further insight into the respective structures of the complexes. From molecular hardness calculation it is observed slightly better reactivity of 2 compared to 3. Molecular Hirshfeld surface analyses support various non-covalent secondary interactions that observed in packing of solid state structure of 2. Complexes 2 and 3 were found to facilitate Suzuki coupling reactions under relatively mild conditions and slightly better yields were obtained in case of 2.

Continuous flow coupling reaction of bromopyridine and styrene catalyzed by amidoxime fiber supported-palladium

Polyacrylonitrile (PAN) fibers were modified by hydroxylamine to obtain amidoxime fibers (AOFs) as the carrier, which was coordinated with PdCl2 solution to prepare amidoxime fibers supported Pd(II) [AOFs-Pd(II)] catalyst. A continuous flow reaction device was established to explore the coupling reaction of bromopyridine with styrene catalyzed by AOFs-Pd(II). The optimization was carried out to obtain the optimal process conditions, including temperature, flow rate, substrate concentration, catalyst stability, substrate applicability. The kinetic equations under continuous flow were obtained by fitting the data from the experiments using Matlab, and the reaction was determined to be a first-order reaction. Using the Arrhenius equation, the activation energy (Ea) was determined to be 7.65 kJ/mol.

Fabrication of Pd-decorated tungsten oxide nanoflakes for hydrogen sensors via facile anodizing oxidation method

Accurate and reliable hydrogen sensing is crucial for safety and efficiency in industries like energy, transportation, and environmental monitoring. This study presents the synthesis and characterization of Pd-decorated WO3 nanoflakes with palladium (Pd) nanoparticles from anodizing derived WO3.2(H2O) nanoflakes for gas sensing applications. We investigate the crystal structure and phase composition of the synthesized nanoflakes using X-ray diffraction (XRD) and Raman spectroscopy, which confirm the presence of well-crystallized monoclinic WO3.2(H2O) phase without any impurities or secondary phases. Field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) reveal the unique morphology of the nanoflakes with irregular edges and varying sizes, as well as the successful decoration of Pd nanoparticles on the nanoflake surface. X-ray photoelectron spectroscopy (XPS) analysis indicates partial oxidation of tungsten species upon interaction with PdCl2 solution. We evaluate the gas sensing characteristics of the decorated nanoflakes towards hydrogen gas, demonstrating an enhanced response at elevated temperatures (>300 °C). The introduction of Pd nanoparticles improves the gas sensing response up to 6000 due to increased hydrogen dissociation and catalytic activity, as well as enhanced electrical conductivity. The response and recovery times of the sensors are rapid, indicating efficient response-recovery behavior. These findings suggest the potential of anodizing method for fabrication of WO3.2(H2O) nanoflakes as promising candidates for gas sensing applications.

Highly Porous Para-Aramid Aerogel as a Heterogeneous Catalyst for Selective Hydrogenation of Unsaturated Organic Compounds.

A new para-aramid aerogel based on a polymer made by the reaction of terephthaloyl dichloride with 2-(4-aminophenyl)-1H-benzimidazol-5-amine (PABI) is introduced. The aerogel readily bound Pd (+2) ions and was used as a hydrogenation catalyst in some industrially actual reactions. The new material, which did not contain p-phenylenediamine moieties, was prepared in two form factors: bulk samples and spherical pellets of 700-900 μm in diameter. Aerogels were synthesized from 1% or 5% solutions of PABI in N,N-dimethylacetamide via gelation with acetone or isopropanol and had a density of 0.057 or 0.375 g/cm3 depending on the concentration of the starting PABI solution. The specific surface area of the obtained samples was 470 or 320 m2/g. Spherical pellets containing Pd were prepared from a solution of PdCl2 in PABI and were used as heterogeneous catalysts for the gas-phase hydrogenation of unsaturated organic compounds presenting the main types of industrially important substrates: olefins, acetylenes, aromatics, carbonyls, and nitriles. Catalytic hydrogenation of gaseous hexene-1, hexyne-3, cyclohexene, and acrylonitrile C=C bond proceeded with a 99% conversion at ambient pressure, but the catalyst failed to reduce acetone at 150 °C and benzene and ethyl acetate even at 200 °C. The only product of acrylonitrile hydrogenation was propionitrile. The prepared catalysts showed high selectivity, which is important for the chemistry of complex organic compounds.

Facile self-repair of ultrathin palladium membranes

Pd membranes can play an important role in H2 separation and purification for the development of sustainable and renewable energies. By supporting on porous substrates, Pd layer thickness can be reduced to several micrometers, thus improving the H2 permeance by several orders of magnitude. However, the supported thin Pd membranes are concomitant with pinhole formation due to either fabrication (e.g., electroless-plating) or thermal treatment, which exist as a remarkable challenge for its widespread applications. This study presents a novel and facile approach for self-repair of Pd membrane defects by immersing the stainless-steel supported Pd membranes in PdCl2 solution. Three membranes were deliberately selected with a low selectivity of 152–1687 (400 ​°C, 0.1Mpa), for which disproportionation reactions between Pd2+ and Fe/Cr/Ni at the defect sites spontaneously occur leading to the formation of Pd particles at the exact point of defects. This self-repair process can be enhanced when applying a high pressure of 30–50 ​bar in the PdCl2 solution for 30 ​min, by overcoming the capillary resistance and penetrating through the pinholes. Interestingly, densely distributed hillocks were observed on the membrane surface probably due to reduction of PdCl2 under following H2 treatment, thus increasing the H2 permeance with a higher effective surface area. The H2/N2 selectivity can be improved by more than one order of magnitude (in the best case from 1687 to 8768) and a long-term stability test of 300 ​h was achieved for the repaired membranes, corroborating the application potential of this approach.

CO Oxidation over Pd Catalyst Supported on Porous TiO2 Prepared by Plasma Electrolytic Oxidation (PEO) of a Ti Metallic Carrier.

A porous TiO2 layer was prepared with the plasma electrolytic oxidation (PEO) of Ti. In a further step, Pd was deposited on the TiO2 surface layer using the adsorption method. The activity of the Pd/TiO2/Ti catalyst was investigated during the oxidation of CO to CO2 in a mixture of air with 5% CO. The structure of the catalytic active layer was studied using a scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), inductively coupled plasma mass spectrometry (ICP-MS), and X-ray diffraction (XRD). The PEO process provided a porous TiO2 layer with a uniform thickness in the range of 5–10 µm, which is desirable for the production of Pd-supported catalysts. A TOF-SIMS analysis showed the formation of Pd nanoparticles after the adsorption treatment. The conversion of CO to CO2 in all samples was achieved at 150–280 °C, depending on the concentration of Pd. The composition of Pd/ TiO2/Ti was determined using ICP-MS. The optimum concentration of Pd on the surface of the catalyst was approximately 0.14% wt. This concentration was obtained when a 0.4% PdCl2 solution was used in the adsorption process. Increasing the concentration of PdCl2 did not lead to a further improvement in the activity of Pd/ TiO2/Ti.

Pd/Cu bimetallic catalyst immobilized on PEI capped cellulose-polyamidoamine dendrimer: Synthesis, characterization, and application in Sonogashira reactions for the synthesis of alkynes and benzofurans

Polyamidoamine dendrimer (PAMAM) is an efficient material for immobilization of Pd(II) complex due to its unique tree-like structure and properties. To the purpose of enhancing of the loading of Cu(II) ions, a polyethyleneimine end-capped microcrystalline cellulose-polyamidoamine dendrimer (G2.5) (MCC-PAMAMG2.5-PEI) was designed and synthetized. The resultant MCC-PAMAMG2.5-PEI was furtherly treated by PdCl2 and CuSO4 solution to afford the corresponding dendrimer-supported Pd/Cu bimetallic catalyst (Pd/Cu@MCC-PAMAMG2.5-PEI). As a result, both Pd(II) and Cu(II) ions were well selectively immobilized within the interior architectures and exterior PEI layers of dendrimers, respectively. The as-prepared catalyst was fully characterized by elemental analysis (EA), inductively coupled plasma atomic emission spectrometry (ICP-AES), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), elemental mappings, energy-dispersive X-ray spectra (EDX), field emission transmission electron microscopy (FETEM), and thermogravimetry analysis (TGA) techniques. The presence of required Pd and Cu elements were confirmed from ICP-AES, XPS, EDX, and elemental mappings analysis, respectively. The synergetic effect between Pd and Cu can be observed by comparing it to the dendrimer supported monometallic Pd and Cu as well as the mixture of dendrimer supported Pd and Cu. The catalyst showed excellent performance in the synthesis of alkynes and benzofurans via Sonogashira reactions and could be reused for seven successive runs without any noteworthy loss of activity. Moreover, its efficiency was compared with other reported catalysts in the same transformations.

Selective Metallization of Polymers: Surface Activation of Polybutylene Terephthalate (PBT) Assisted by Picosecond Laser Pulses

The selective metallization of nonconductive polymer materials has broad applications in the fields of integrated circuit technology and metallized patterns. This work discusses a methodology to pattern metal tracks on polybutylene terephthalate substrates. The process consists of three steps: 1) surface patterning with picosecond laser pulses (1030 nm) in air, 2) Pd seeding via treatment in PdCl2solution, and 3) selective metallization via electroless copper deposition. Picosecond laser irradiation promotes not only surface roughening but also chemical modification to enable Pd seeding as the polymer surface acquires the ability to reduce Pd(II)‐chloride species to metallic Pd. The laser parameters, as well as the PdCl2concentration and seeding temperature, have an influence on the polymer surface morphology, the concentration and distribution of metallic Pd, and the copper layer properties. Homogeneous copper layers with well‐defined geometries, good coating‐substrate adhesion, and high electrical conductivity can be obtained. This is ascribed to the synergistic effect of the chemical surface activation and roughness development (from 0.13 to ≈1.6 μm). As the patterning and surface activation are performed in air, directly on the as‐received polymer substrate, this methodology shows great potential for metallization of electronic devices with 3D complex geometries.

Synthesis of a dual‐functionalized carbon‐based material as catalyst and supercapacitor for efficient hydrogen production and energy storage: Pd‐supported pomegranate peel

AbstractIn the current study, firstly, pomegranate peel (PP) was treated with phosphoric acid (H3PO4) and palladium chloride (PdCl2) solution. So, the PP‐supported Pd (PP‐H3PO4‐Pd) catalyst was synthesized for hydrogen production by the methanolysis reaction. In this context, different burning temperatures (300°C, 400°C, 500°C, and 600°C), and burning times (30, 45, 60, and 90 minutes) were examined to test the activity of the PP‐H3PO4‐Pd catalyst by the methanolysis reactions. As a result of studies, the most active catalyst was obtained by burning 45 minutes at 300°C (2 mL PdCl2solution 2% w/w). The maximum hydrogen production rate (HPR) obtained at 60°C by the methanolysis reaction was found as 37 240.4 mL min−1 g cat−1and the activation energy was calculated to be 26.83 kJ mol−1. Within the scope of this study, secondly, this PP‐H3PO4‐Pd catalyst was used as a supercapacitor active material for the first time to store electricity. Electrochemical characterization results were substantially similar to supercapacitor curves in the literature. At the current density of 1 A/g, the gravimetric capacitance of the prepared electrode was calculated as 84 F/g. Considering factors such as capacity, cost, and efficiency; the capacitance values of the produced ultracapacitor have a significant level.

Carboxymethylcellulose-supported Palladium Nanoparticles Formed <i>in situ</i> for Suzuki-Miyaura Coupling Reaction

A green experiment is described here for direct fabrication of carboxymethylcellulose-supported palladium nanoparticles (PdNPs@CMC) in situ through a simple self-assemble and self-reduction process between carboxymethylcellulose (CMC-Na) and PdCl2 solution. The PdNPs@CMC was well characterized by ICP, UV-Vis, XPS, FTIR, SEM, and TEM techniques. The in situ synthesized PdNPs@CMC was proved to be an efficient catalyst for Suzuki-Miyaura coupling reaction under mild aerobic conditions. The superior catalytic performance of PdNPs@CMC is attributed to the coordination with carboxyl groups (−COO−) and free hydroxyl groups (−OH) as well as polymeric capping effect of CMC. Moreover, the catalyst showed no significant loss of its activity at least three consecutive cycles. This laboratory class is involved in the preparation and characterization of PdNPs@CMC as well as its catalytic application in Suzuki−Miyaura cross coupling reaction under green conditions. This laboratory class is suggested to divide into two parts. The first part includes the fabrication of catalyst in situ through a self-assemble and self-reduction of Pd(II) with CMC−Na, and characterization of the as-prepared catalyst using various techniques. The second part employs the resulting catalyst to perform a microscale Suzuki-Miyaura reaction, recycling of catalyst, and characterization of the product. By design, this comprehensive experiment set up for the third-year undergraduate, and aim to make students comprehend the concept of ion-exchange reaction, reduction reaction, carbon-carbon coupling reaction, supported catalysts, nanoparticles, and green chemistry as well as train the fundamental operation capability of students, and improve their experimental skills.

A dual functional material: Spirulina Platensis waste-supported Pd-Co catalyst as a novel promising supercapacitor electrode

In the present study, Spirulina Platensis waste-supported Pd-Co (SPW-Pd-Co) catalyst was used as an efficient catalyst for the methanolysis reaction of sodium borohydride (NaBH4); moreover, the produced SPW-Pd-Co catalyst was tested as a supercapacitor electrode material for the first time. In this context, the SPW-Pd-Co catalyst was synthesized by the treatment of the Spirulina Platensis waste (SPW) with 1–7 M HCl, 1 mL PdCl2 solution (2% w/w) and 1, 2, 3, 4, and 5 mL CoCI2·6H2O solution (5% w/w). Under optimum conditions, the most active catalyst was obtained by burning with 3 M HCl-Pd-4 mL Co2+ solution at 600 °C for 90 min. The maximum rate of hydrogen generation (HGR) obtained at 30 °C from the NaBH4 methanolysis reaction was found to be 5497.7 mLmin-1gcat−1, and the catalyst activation energy was found to be 10.32 kJ mol−1. The gravimetric capacitance of the prepared electrode was calculated as 50 F/g at 2 A/g current density. The capacitance values of the supercapacitor are at a significant level in terms of capacity and the cost.

The Effect of Addition Method of Impregnation Solution on Properties and Performance of Pd-Ag/Al2O3 Catalyst in Tail-End Acetylene Selective Hydrogenation

The impregnation of alumina support with PdCl2 solution was investigated in batch and semi-batch operation modes using a recycle packed-bed reactor. UV-visible analysis was used to evaluate the kinetics of Pd adsorption on alumina support. Transient palladium adsorption data showed that Pd adsorption was very rapid completing within few minutes. Bi-metallic Pd-Ag/Al2O3 catalysts were synthesized by sequential impregnation method. CO-chemisorption, CO-TPD and FE-SEM tests were used to characterize the synthesized bi-metallic samples. Catalytic performance of the samples was evaluated for tail-end acetylene selective hydrogenation process in a fixed-bed reactor. Moreover, the deactivation of the catalysts was evaluated mathematically by integral method of analysis, considering reaction kinetics as power laws in terms of nth orders in H2 and C2H2 partial pressures. It was observed that by batch-wise addition of Pd precursor solution, a sample was obtained with lowest amount of Pd dimmers that had highest ethylene selectivity and lowest hydrogenation reaction rate.

Investigation of Pd-Containing Co3O4/C Catalysts for Oxygen Reduction Reaction

Because of the energy crisis, air pollution and global warming it is necessity of technologies that creates sustainably, highly efficient and green energy resources. That is the reason why fuel cells are one of the best power sources – they convert chemical energy into electrical energy and do not contaminate the environment. The main difference between fuel cells and usual batteries is that fuel cell requires a continuous source of fuel (ethanol, methanol, ethylene glycol etc.) and oxygen to sustain the chemical reaction. It is well known that Pt-based catalysts are usually used in fuel cells, however recently, the search of new catalysts with reduced amount of Pt or even non-noble metal catalysts is in progress. Pd-based electrocatalysts have been studied as alternative because of their lower cost and efficient electrocatalytic activities for oxygen reduction (ORR) and fuel oxidation (ethanol, methanol, ethylene glycol etc.) reactions.In this paper we investigated electrocatalytic activity of the Co3O4/C based Pd catalysts towards oxygen reduction reaction. The new catalysts were prepared using few different synthesis steps. At first Co3O4 was deposited on carbon using microwave irradiation at 120 ºC for 3h. Then the obtained Co3O4/C powder was impregnated by Pd in 0,0014 M PdCl2 solution. Further, part of the Co3O4/C powder and impregnated Co3O4/C powder was annealed at 400 ºC for 3h. Depending on the fabrication conditions four different composition of catalyst was obtained. The composition, morphology and structure of the prepared catalysts were characterized using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Electrochemical measurements have been carried out using linear sweep voltammetry (LSV) using rotating disk electrode (RDE) method.The XRD and XPS data have been showed that the constitution of obtained catalysts was following: Co3O4/C was obtained after microwave irradiation heating, PdCox(OH)y/C constitution was estimated for catalyst impregnated in 0,0014 M PdCl2 solution and Co3O4/C-T and PdOCo3O4/C catalysts were obtained annealed at 400 ºC for 3h.It has been found that the impregnation of the Co3O4/C substrate by Pd as well as annealing of primary materials strongly enhanced electrocatalytic activity of investigated catalysts towards oxygen reduction reaction. The ORR activity of the catalysts has been found to increase as follows Co3O4/C < Co3O4/C-T < PdCox(OH)y/C < PdOCo3O4/C ≤ Pt/C. The ORR onset potential reached the most positive potential values in the same line and was equal to 0.78 < 0.83 < 0.91 < 0.92 < 0.95 V.It has been determined that the PdOCo3O4/C catalyst showed the highest electrocatalytic activity for ORR compare to the PdCox(OH)y/C and Co3O4/C catalysts and was very similar to Pt/C.

Surface metallization of PET sheet: Fabrication of Pd nanoparticle/polymer brush to catalyze electroless nickel plating

Electroless nickel plating provides a rapid and low-cost approach to prepare surface-metallization material, but complicated technology would increase cost and restrict its application. In this work, a new kind of Pd nanoparticle/polymer brush (Pd/PB) catalytic solution (AS) with a mixture of deionized water, ethanol, 3-aminopropyltriethoxysilane (KH550), PdCl2 solution was designed to modify and activate polyethylene terephthalate (PET) simultaneously. Pd nanoparticle could be adsorbed by PB with –NH2, Si–O–Si groups from hydrolyzed KH550. An activated layer with Pd/PB structure established on PET surface after coating AS solution. The generated Ag/PB that served as seed to catalyze the electroless nickel plating. As a result, a facile route for electroless nickel plating was achieved. The maximum effective thickness, rupture work and adhesion of Ni-plated coating were about 0.8 μm, 0.4 J/m2, and 5B, respectively, and it maintained considerable conductivity even after 1000 times of cyclical bending. This dependable technology has great potential application in the preparation of metal-polymer material.

Pd quantum dots loading Ti3+,N co-doped TiO2 nanotube arrays with enhanced photocatalytic hydrogen production and the salt ions effects

Pd quantum dots (QDs) loading Ti3+,N co-doped TiO2 nanotube array (NTA) films were prepared by anodic oxidation of Ti foils, followed by calcination at 400 °C and Pd photo-depositions using a PdCl2 solution. The photocatalytic hydrogen production activity of the Pd QDs loading Ti3+,N co-doped TiO2 NTA was tested under UV–vis light irradiation in a methanol aqueous solution and compared with those of Ag and Au loaded Ti3+,N co-doped TiO2 NTAs. The effects of Pd content, salt ions and catalytic reaction temperature on the photocatalytic activities of the Pd QDs loading Ti3+,N co-doped TiO2 NTA catalysts were explored systematically. The photocatalytic reaction mechanism was proposed based on the experimental results. The results show that the hydrogen evolution reaction (HER) rate (17.6 µmol cm−2h−1) over the Pd QDs loading TiO2NTA/Pd10 (10 cycles of Pd photo-depositions) was increased to 16 times higher than that of the unloaded TiO2NTA (1.1 µmol cm−2h−1). Interestingly, adding small amount of alkali salt (0.5 g L−1) in the preparation process of the TiO2 NTAs or in the photocatalytic reaction medium (1 g L−1) can further increase the HER rates distinctly (2.7–3.4 times).

Synthesis of Pd nanoparticle-decorated SnO2 nanowires and determination of the optimum quantity of Pd nanoparticles for highly sensitive and selective hydrogen gas sensor

Pd nanoparticle-decorated SnO2 nanowires were synthesized to fabricate a highly selective and sensitive hydrogen gas sensor. The SnO2 nanowires were synthesized via a vapor–liquid–solid process, and Pd nanoparticles were decorated by a UV irradiation process using 1 mM PdCl2 solution to improve the hydrogen sensing properties of SnO2 nanowires. To generate Pd nanoparticles on the surface of SnO2 nanowires, 254 nm UV light was irradiated on SnO2 nanowires that were immersed in PdCl2 aqua solution, and the irradiation time was manipulated to control the number of Pd nanoparticles. The Pd nanoparticle-decorated SnO2 nanowires showed different hydrogen sensing responses followed by quantity of Pd nanoparticles, and the response of the optimum number of Pd nanoparticle-decorated SnO2 nanowires was 12.7 times that of bare-SnO2 nanowires when exposed 100 ppm of hydrogen gas. Furthermore, the selectivity of this nanowire-based sensor also improved as the Pd nanoparticles were decorated. The SnO2 nanowires exhibited similar sensing responses to several gases, but the hydrogen sensing response increased significantly after Pd nanoparticle decoration. In this case, the sensing response to hydrogen was 5 times higher than that of ethanol gas that showed the second-best response to the sensor. This improvement resulted from the catalytic effect of Pd nanoparticles and the formation of Schottky junctions between Pd nanoparticles and SnO2 nanowires. The mechanisms of the improved hydrogen sensing response of Pd nanoparticle-decorated SnO2 nanowires were discussed, and the optimum quantity of Pd nanoparticles required to obtain the best hydrogen sensing properties was discussed in this research.

Ultrasonically driven green synthesis of palladium nanoparticles by Coleus amboinicus for catalytic reduction and Suzuki-Miyaura reaction

A novel ultrasonically driven bio-reduction method was adopted to reduce the palladium chloride into palladium nanoparticles (PdNPs@CA) using coleus amboinicus extract as a green synthetic protocol. XRD confirms the formation of phase pure cubic Pd nanoparticles with the crystallite size range of 40−50 nm. The UV–vis spectrum reveals the formation of Pd nanoparticles by the disappeared peak at 480 nm of PdCl2 solution. The size distribution and surface morphology of prepared Pd nanoparticles showed spherical shaped nanoparticles with less agglomeration. The catalytic reduction behaviour of the Pd suspension is studied by 4-nitro phenol reduction process in 8 min further confirms its high catalytic performance. Synthesized PdNPs@CA were explored in ultrasound promoted Suzuki-Miyaura coupling reaction to determine the catalytic behaviour with ultrasonic frequency of 40 kHz and power of 150 W (Power sonic 410 bath sonicator) and its recycling ability is determined. It was found that aryl halides reacted with aryl boronic acids to obtain biaryl compound with excellent reaction yields in the presence of PdNPs@CA only in 30 min using PEG-400 as a green solvent. PdNPs@CA can be recovered efficiently and reused for 7 cycles without loss of its catalytic property.

A new approach of pH-IEGFET sensor based on the surface modification of macro porous silicon with palladium nanoparticles

This work investigates the effect of the Palladium nanoparticles (PdNPs) on the characteristics and pH sensitivity of an interdigitated electrode extended-gate field-effect transistor (pH-IEGFET) sensors based on the bare n-type macro porous Si (n-macro PSi) layer. The synthesized bare porous layer was fabricated by photo electrochemical etching process of n-type (100) using short-wavelength 410 nm and intensive laser power density 80 mW/cm2. The surface morphology of n-macro PSi was modified by inserting PdNPs to form PdNPs/n-macro PSi hetero structure layers via simple and fast immersing process in PdCl2 solution for about 14 min and 20 min by the ion reduction process. The fabricated sensors have been verified in the range of pH from 3 to 11 at the ambient temperature. Specific features of n-macro PSi and hybrid structure were investigated using a scanning electron microscope, energy dispersive x-ray spectroscopy (EDX) analysis and x-ray diffraction. It was found that the morphology and the size of the deposited PdNPs intensely influence on the PdNPs/ n-macro PSi hetero structure pH-IEGFET sensor. The efficient pH sensing process was obtained for n-macro PSi pH sensor with the lowest size of PdNPs deposited on the external walls of the n-macro PSi pores. Significant enhancement of sensitivity of about 42.89 mV/pH and linearity of 0.9948 was achieved, compared with the bare n-macro PSi pH sensor having a sensitivity of 25.12 mV/pH and linearity of 0.9392. This sensitivity enhancement is due to the additional specific surface area of PdNPs which causes improved it.