Photoelectron Spectroscopy Methods Research Articles

Comparison of the HDS DBT reaction using bulk and supported catalysts

The paper describes in detail the procedure for the preparation of a granular bulk NiMoW catalyst and a supported reference NiMo/Al2O3 catalyst. Mention is made of investigations of the supported and bulk catalysts by various physico-chemical methods (nitrogen adsorption-desorption method, X-ray photoelectron spectroscopy, TPD-NH3, HRTEM and X-ray diffraction analysis). The experiments to estimate catalytic activity and compare rate constant of hydrodesulfurization of dibenzothiophene using both catalysts have been carried out. It is shown that textural properties of the catalysts significantly differ. The supported catalyst has more developed specific surface area and pore volume than the bulk catalyst. TPD-NH3 showed an increased acidity of the supported catalyst in comparison the bulk catalyst. It is shown by the X-ray photoelectron spectroscopy method that in both samples Mo on the surface is present exclusively in the form of Mo4+ ion. However, the bulk catalyst differs from the supported catalyst in that it contains a larger amount of Ni as part of the active NiMo(W)S phase. The catalytic activity tests demonstrated that the bulk catalyst is more active at 240, 250 and 260°C, it is discovered that the rate constant in hydrodesulfurization of dibenzothiophene for the bulk NiMoW catalyst is twice higher at 240ºC than that of the supported NiMo/Al2O3 catalyst.

Effect mechanism of phosphorous-containing additives on carbon structure evolution and biochar stability enhancement

The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar. The effect of K3PO4 addition on the yield, chemical composition, characteristic functional groups, macromolecular skeleton, graphite crystallites, and stability of biochar was studied in this paper using two-dimensional infrared correlation spectroscopy (2D-PCIS), X-ray photoelectron spectroscopy, Raman spectrum, and other characterization methods combined with thermal/chemical oxidation analysis. It is discovered that adding K3PO4 may effectively minimize the graphitization temperature range and increase biochar's yield, aromaticity, H/C ratio, and proportion of refractory/recalcitrant organic carbon. The 2D-PCIS and Raman analysis revealed that K3PO4 mostly promoted the dehydrogenation and polycondensation process of the aromatic rings in the char precursor, transforming the amorphous carbon structure of biochar into an ordered turbostratic microcrystalline structure. K3PO4 enhanced biochar stability mostly at medium-high temperatures (350 ~ 750℃) by stimulating the transformation of unstable structures of biochar to stable carbon-containing structures or by inhibiting the interaction of its active sites with oxidants through the mineralization process. A 20% phosphorus addition increased biochar's refractory index (R50) by roughly 11%, and it also boosted biochar's oxidation resistance (H2O2 or K2CrO4) efficiency, reducing carbon oxidation loss by up to 7.31%. However, at higher temperatures (> 750 ℃), the doping of phosphorus atoms into the carbon skeleton degraded the biochar structure's stability. The results of this study suggest that using exogenous phosphorus-containing additives is an efficient way to improve the stability of biochar.Graphical abstract

Advancing water treatment: Harnessing cyclodextrin metal-organic frameworks with dual protonation sites for enhanced sulfate adsorption efficiency

TTH-CD-MOF was synthesized for sulfate ion adsorption from aqueous solutions, employing cross-linking modification of γ-CD-MOF with N-hydroxyethyl-morpholine as the modifier and triisocyanate as the cross-linking agent. The adsorbent underwent characterization through Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption-desorption, and other analytical methods. Additionally, the impact of factors such as pH, adsorbent dosage, initial concentration, and ionic strength on adsorption performance was investigated. Adsorption experiments demonstrated the robust efficiency of TTH-CD-MOF for SO42- up to 95.3%, conforming to Langmuir isothermal and pseudo-second-order kinetic models, and higher temperatures favored SO42- adsorption. The maximum adsorption capacity was 189.51 mg·g−1 (25 °C). The adsorption mechanism comprised electrostatic interaction, adsorption within the cavities and pores of γ-CD-MOF. TTH-CD-MOF demonstrates effective sulfate removal from aqueous solutions, establishing its potential as an efficient anion adsorbent.

Electronic structure control of IrO2 via conjugated polymer support for highly efficient oxygen evolution reaction

In this paper, we report synthesis of novel nanoparticle catalyst of iridium oxide supported on conjugated polymer along with evaluation of activity and durability for oxygen evolution reaction. The IrO2/poly(BIAN-thiophene)/TNT catalyst was prepared from iridium complex and poly(BIAN-thiophene)/TNT by hydrothermal method. The synthesized IrO2/poly(BIAN-thiophene)/TNT catalysts was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transfer-infrared spectroscopy, x-ray photoelectron spectroscopy and electrochemical methods. The average particle size of the IrO2 particles on poly(BIAN-thiophene)/TNT was 2.5 nm. The XPS measurement revealed that Ir complex was completely converted to iridium oxide through hydrothermal treatment. The IrO2/poly(BIAN-thiophene)/TNT catalyst showed sufficient performance for OER activity and durability in acidic condition. Our results indicate that IrO2/poly(BIAN-thiophene)/TNT is one of the prospective candidate catalysts for water splitting.

Facile Transfer Hydrogenation of N-Heteroarenes and Nitroarenes Using Magnetically Recoverable Pd@SPIONs Catalyst.

Catalysts with active, selective, and reusable features are desirable for sustainable development. The present investigation involved the synthesis and characterization of bear-surfaced ultrasmall Pd particles (<1 nm) loaded onto the surface of magnetic nanoparticles (8-10 nm). The amount of Pd loading onto the surface of magnetite is recorded as 2.8 wt %. The characterization process covered the utilization of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS) methods. The Pd@Fe3O4 catalyst has shown remarkable efficacy in the hydrogenation of quinoline, resulting in the production of >99% N-ring hydrogenated (py-THQ) product. Additionally, the catalyst facilitated the conversion of nitroarenes into their corresponding aniline derivatives, where hydrogen was achieved by H2O molecules with the aid of tetrahydroxydiboron (THDB) as an equilibrium supportive at 80 °C in 1 h. The high efficiency of a transfer hydrogenation catalyst is closely related to the metal-support synergistic effect. The broader scope of functional group tolerance is evaluated. The potential mechanism underlying the hydrogenation process has been elucidated through the utilization of isotopic labeling investigations. The application of the heterocyclic compound hydrogenation reaction is extended to formulate the medicinally important tubular polymerization inhibitor drug synthesis. The investigation of the recyclability of Pd@Fe3O4 has been conducted.

Improved Adhesion of Direct Copper Seed Layer by Medium-Vacuum Sputtering Using Vacuum Ultraviolet Light

A sputtering method is used to form the seed layer for copper electric plating. In general, copper sputtering has weak adhesion to resin, so titanium sputter is combined to increase the adhesion strength. However, etching in the lithography process requires two types of processes, titanium and copper metal. Adhesion strength was improved by performing vacuum ultraviolet (VUV) treatment as a pretreatment for medium-vacuum sputtering. We discovered the relationship between the hydroxyl groups on the resin surface and the adhesion strength by the chemical modification XPS method. Furthermore, by XPS analysis of the peeled copper interface, the adhesion mechanism between the resin and copper due to VUV irradiation was estimated. We evaluated the absorption properties in the vacuum ultraviolet region of a thinly polished glass epoxy resin. We investigated the behavior of functional groups at the interface and considered the effect of vacuum ultraviolet light in the depth direction.

Enhanced removal of copper ions from wastewater using small spherical Fe-N-C material via selective electro-sorption: Experiment and calculation

In the current research, the resource recovery technology for Cu-containing wastewater from electroplating is still a difficult problem. Capacitive deionization technology (CDI) has received widespread attention for its strengths of convenient operation, low cost, and environmentally friendly. In this paper, Fe-N-C was prepared as the electrode material for the treatment of Cu-containing wastewater by capacitive deionization technology through one-pot thermal method. The optimum treatment conditions of Fe-N-C for Cu-containing wastewater were voltage equal to 1 V, pH = 5, and the inlet flow rate was 5 mL/min. The electro-adsorption capacity of a single Cu-containing solution of 400 mg/L could reach 389.4 mg/g. Meanwhile, by carrying out ion competition experiments on five cations, namely Zn2+, Na+, Mg2+, K+, and Cu2+, which demonstrated Fe-N-C had a significant selectivity for the electro-adsorption removal of Cu2+. Theoretical calculations revealed that Fe3N and Fe4N were more dominant for Cu2+ adsorption energy and more binding for competing ions in the monovalent state, but had less practical effect on Cu2+ adsorption. The morphology of the Fe-N-C was analyzed in more depth by X-ray photoelectron spectroscopy (XPS) and other characterization methods. Combined with density functional calculations, Cu would not only displace with Fe in FeXN to form a more stable CuXN structure, but also combine with FeXN to form a Cu-FeXN structure. This is conducive to accelerating the application of CDI to recover Cu2+ from heavy metal wastewater.

Electronic and Crystal Structure of New CrxZrSe2 Intercalation Compounds.

New intercalation compounds CrxZrSe2 were synthesized and thoroughly studied. Cr atoms were found to occupy the positions both tetrahedrally and octahedrally coordinated by the Se atoms in the interlayer gap. The magnetic properties and electrical resistivity were studied in the temperature ranges of 2.4-300 K and 80-340 K, respectively. The compounds change their behavior from semiconducting (x = 0.1) to metallic (x > 0.1). The magnetic interaction strongly depends on the Cr content and temperature. The spin-glass state with antiferromagnetic interaction exists at T < Tcrit for CrxZrSe2 with x ≤ 0.2, while at x ≥ 0.3 ferromagnetic contribution arises as well. The single crystals of CrxZrSe2 were grown to study the electronic structure of the materials. A combination of the X-ray photoelectron spectroscopy (including that across Cr 2p-3d and Zr 3p-4d resonance) and X-ray absorption spectroscopy methods allowed to propose the location of the Cr 3d-states in the Se 3p-Zr 4d energy gap.

Efficient activation of peroxymonosulfate by molybdenum disulfide cocatalysis of Co and N co-doped porous carbon for degrading perfluorooctanoic acid: Synergistic effect of Co and N by molybdenum and its mechanism

In this study, precursor ultrathin molybdenum disulfide nanosheets and ZIF-67 was selected to prepare Co and N co-doped porous carbon by the support of Mo (MoS2/Co@NPC) to activate peroxymonosulfate (PMS) for perfluorooctanoic acid (PFOA) degradation. The morphology, crystal form and composition of MoS2/Co@NPC are studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and other methods. In MoS2/Co@NPC/PMS process, PFOA was completely degraded in 180 min at pH 7, 0.3 g/L catalyst, 0.1 mM PMS and reaction temperature of 25 °C. The degradation efficiency was much higher than that in other systems. The oxidative species for PFOA degradation was studied using free radical quenching experiments and electron paramagnetic resonance (ESR) tests. SO−4 plays a major role in the degradation of PFOA, OH plays an auxiliary role, and 1O2 contributes the least. The effect of different types and positions of cobalt‑nitrogen and molybdenum atoms on the electrocatalytic activity was investigated by density functional theory (DFT) calculations. The co-doping of Co and N into carbon-based materials can synergistically enhance by Mo for the activation of PMS. The unsaturated S atoms on the surface of metal sulfides can trap protons to form H2S while exposing the reducing metal active site, which also accelerates the rate-limiting step of the Co3+/Co2+ conversion. The core-shell structure of Co@NPC doped with Mo has the characteristics of improving the electron transfer ability of carbon, promoting the mass transfer of reactants, and preventing cobalt metal agglomeration and metal dissolution. The degradation pathways of PFOA were investigated and three possible pathways were proposed. In addition to PFOA, MoS2/Co@NPC-800/PMS system can also remove contaminant in pharmaceutical wastewater, indicating that the process has potential application value in practical wastewater treatment.

Rational design of self-assembled copper oxide nanoparticles into hierarchical nanorods with high-surface-area for environmental remediation of wastewater

The coordinated generation of hierarchical structures is a difficult task that necessitates accurate control over a number of variables such as assembly shape, array dimensions, peripheral spacing, and uniformity. In this study, we successfully synthesized self-assembled copper oxide nanomaterials using hydrothermal processes. By aggregating copper oxide nanoparticles (diameter 4–6 nm), we were able to create a hierarchical rod-like morphology with highly homogeneous particle morphology and feature sizes ranging from 50 to 200 nm. We thoroughly investigated the methods of self-assembly of CuO nanorod formations, as well as the influence of templates on the materials' structure. Our analysis included powder X-ray diffraction (XRD), TEM, N2 sorption, and X-ray photoelectron spectroscopic (XPS) methods. N2 adsorption–desorption isotherm indicated high surface areas (125–190 m2/g) and limited pore diameter (less than 5 nm) for different samples. Furthermore, XPS examination demonstrated that the materials have a high concentration of Cu2+ groups, which serve as active sites for dichromate anion adsorption. We further investigated the adsorption process using Langmuir, Freundlich and Weber–Morris models and found that these CuO nanorods can perform as a highly powerful and recyclable adsorbent for hazardous dichromate from wastewater. Our findings have significant implications for the progress of new materials for environmental remediation and other applications.

Coatings deposited by physical vapor deposition (PVD) on high-speed steel used in the processing of wood materials

ABSTRACT In this study the use of AlTiN/aCN, TiAlN/TiN and three types of CrAlN/CrN coatings deposited on HSS steel was investigated. These protective coatings were prepared using PVD (physical vapor deposition) method. The objective of this study was to compare the microstructure, chemical composition and properties of Cr, Al or Ti based coatings deposited on a substrate made of high-speed steel HSS. The thicknesses of coatings based on titanium were approx. 4 µm, and those based on chromium were less than 1 µm. The morphology and chemical composition were studied using scanning electron microscopy (SEM) and X-ray dispersion spectroscopy (EDX). The X-ray photoelectron spectroscopy (XPS) method was applied. The adhesion was evaluated by scratch test. Nanohardness and durability tests of uncoated and coated knifes were performed. It was found that the knifes made of HSS covered with two-layer TiAlN/aCN coating exhibited the best durability characteristic. Coatings containing chromium were less durable due to their small thickness. The highest nanohardness was found in the AlTiN/TiN coating due to its multi-layer nature. The nanohardness of the other coatings is comparable but more than two times lower compared to the multilayer AlTiN/TiN nanocoating.

The influence of implantation of Mg+ ions and subsequent annealing on the composition, electronic structures, emission and optical properties of CdF2

Relevance. In the case of bombardment with Mg metal ions, the changes are accompanied by the introduction of metal atoms and the formation of various types of compounds. Thus, CdF2 is intensively decomposed into components in the near-surface layer in the process of ion implantation. A small part of these components can be sprayed from the surface. Due to the high chemical activity, almost all of the liberated fluorine atoms again enter into a chemical bond with both the atoms of the alloying element and the atoms of cadmium. Consequently, three-component compounds are formed in the near-surface layer. Therefore, it is necessary to define the electronic states, band energy, and optical parameters of CdF2 and Cd0.6Mg0.4F2 films. Purpose. The composition, structure, and properties of CdF2 implanted with Mg+ ions in combination with thermal and laser annealing for the first time were the research aims. Methodology. The experimental studies were carried out at a vacuum of at least 10-7 Pa using the methods of Auger electron spectroscopy (AES) and ultraviolet photoelectron spectroscopy (UVES). The depth distribution profiles of atoms were determined by the AES method in combination with layer-by-layer etching of the surface with Ar+ ions with E0=2-3 keV. Results. CdF2 is intensively decomposed into components in the near-surface layer in the process of ion implantation. Consequently, three-component compounds are formed in the near-surface layer. Band-energy parameters and densities of the state of electrons in the valence band of this film are determined. Conclusions. The effect of the implantation of Mg+ ions on the composition and electronic structure of single-crystal CdF2/Si(III) films was studied for the first time. The densities of electronic states, band-energy and optical parameters of CdF2 and Cd0.6Mg0.4F2 films have been determined

A brief overview of X-ray photoelectron spectroscopy characterization of thin films

Preparation and characterization of nanostructured thin films have been reported by many researchers. X-ray photoelectron spectroscopy (XPS) method has been used over few decades in different fields such as superconductor, semiconductor, metallurgy and catalysis. In this work, elemental oxidation state, electronic state, chemical structure and chemical composition were investigated for metal sulfide, metal selenide, metal oxide and metal telluride films. Evaluation of binding energy for the obtained samples was reported. XPS spectra showed that annealing treatment has a very strong effect on the composition of the films. The elemental oxidation state and electronic state were strongly dependent on the specific experimental conditions.

Excitation Energy-Dependent Decay Dynamics of the S1 State of N-Methyl-2-pyridone.

The UV-induced decay dynamics of N-methyl-2-pyridone is investigated using a femtosecond time-resolved photoelectron spectroscopy method. Irradiation in the wavelength range of 339.3-258.9 nm prepares N-methyl-2-pyridone molecules with very different vibrational levels of the S1(11ππ*) state. For v' = 0 (origin) and a few low-energy vibrational levels slightly above the S1 state origin, the radiative decay channel is in operation for some specific vibrations. This is revealed by the excited-state lifetime of ≫1 ns. In addition, some other nearby S1 vibronic states have a much shorter lifetime in the range of several picoseconds to a few tens of picoseconds, indicating that the radiation-less decay to the ground state (S0) via internal conversion is the dominant channel for them. As the pump wavelength slightly decreases, the radiative decay is suddenly not important at all, and the deactivation rate of the S1 state becomes faster. At shorter pump wavelengths, the lifetime of highly excited vibrational states of the S1 state further decreases with the increase in the vibrational excess energy. This study provides quantitative information about the excitation energy-dependent decay dynamics of the S1 state of N-methyl-2-pyridone. Methyl substitution effects on the excited-state dynamics of 2-pyridone are also discussed.

Prospects of Using Ruthenium within the Composition of Three-Way Palladium–Rhodium Catalysts

The possibility of using ruthenium within the composition of palladium-rhodium catalysts used to neutralize the exhaust gases of vehicles with gasoline engines was investigated. Thermolysis of the supported precursor in oxidizing and reducing media leads to the formation of samples with different initial catalytic activity. Stability of trimetallic systems is compared under conditions of prompt thermal aging with reference samples of similar chemical composition, but obtained by mechanical mixing of monometallic catalysts. The obtained results allow one to conclude that the alloy nanoparticles are more stable, and the thermolysis of the precursor in the reducing medium contributes to a higher initial activity of the catalyst in the oxidation of CO. According to the X-ray photoelectron spectroscopy method, the high thermal stability of trimetallic catalysts is due to the constant ratio of metals on the surface of the support during the catalytic reaction.

Organic Semiconductor Interfaces and Their Effects in Organic Solar Cells†

Comprehensive SummaryEnergy levels and energy level alignment at interfaces play a decisive role in designing efficient and stable organic solar cells (OSCs). In this review two usually used technologies in organic photovoltaic communities for measuring energy levels of organic semiconductors, photoelectron spectroscopy and electrochemical methods, are introduced, and the relationships between the values obtained from the corresponding techniques are compared. The energy level and energy level alignment across the interfaces involved in solution processed organic photovoltaics are described, and the corresponding integer charge transfer model for predicting and explaining energy level alignment is presented. The effects of the interface properties in designing efficient binary and ternary OSCs were discussed. The effects of environmental factors mainly including water vapor, oxygen gas and thermal annealing on energy levels and energy level alignment involved in photoactive layers, and the subsequent effects on the corresponding OSC properties are given.

Kinetics of Electrocatalytic Oxidation of Gallic Acid by Activated Glassy Carbon Electrode in Acidic Medium

AbstractAn electrochemically functionalized glassy carbon (GC) electrode was prepared to study Gallic acid (GA) oxidation reaction in an acidic medium. The functionalized GC electrode was found to enhanced GA oxidation reaction in acidic medium by lowering oxidation potential and increasing corresponding current in comparison to a pristine GC. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and x‐ray photoelectron spectroscopy (XPS) methods were used to analyze functionalized GC surface. The development of electropositive C=O functional groups were assumed to enhance the catalytic process. The specific capacitance of the electrode was calculated to be 92.91 μF by analysing EIS. Kinetics of GA oxidation over activated GC was calculated from CVs data. By analysing concentration dependent CVs it was found that the electrode process followed mass transfer limited first order kinetics. The GA oxidation mechanism is potential‐dependent. For potentials above 0.42 V, the oxidation reaction involves the transfer of 2e− and 2H+ via a concerted mechanism, while at potentials below 0.42 V, the mechanism is stepwise. The reaction‘s standard rate constant (k°) was evaluated as 2.08×10−4 cm s−1.

Temperature-Dependent Structural and Electrical Properties of Metal-Organic CVD MoS2 Films.

Metal-Organic CVD method (MOCVD) allows for deposition of ultrathin 2D transition metal dichalcogenides (TMD) films of electronic quality onto wafer-scale substrates. In this work, the effect of temperature on structure, chemical states, and electronic qualities of the MOCVD MoS2 films were investigated. The results demonstrate that the temperature increase in the range of 650 °C to 950 °C results in non-monotonic average crystallite size variation. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and Raman spectroscopy investigation has established the film crystal structure improvement with temperature increase in this range. At the same time, X-Ray photoelectron spectroscopy (XPS) method allowed to reveal non-stoichiometric phase fraction increase, corresponding to increased sulfur vacancies (VS) concentration from approximately 0.9 at.% to 3.6 at.%. Established dependency between the crystallite domains size and VS concentration suggests that these vacancies are form predominantly at the grain boundaries. The results suggest that an increased Vs concentration and enhanced charge carriers scattering at the grains' boundaries should be the primary reasons of films' resistivity increase from 4 kΩ·cm to 39 kΩ·cm.

Высокоточный элементный анализ образцов горных пород и археологических артефактов методом рентгеновской фотоэлектронной спектроскопии

Introduction. Despite a fairly wide range of methods currently used for the chemical and elemental analysis of rocks and archaeological artifacts, many questions regarding the qualitative and quantitative accuracy of the analysis and the distribution of elements over the surface and volume of the sample with a high degree of locality remain open. In this regard, to solve these issues, in this work, for the first time, the method of X-ray photoelectron spectroscopy (XPS) was proposed and tested, which allows unambiguous and high-precision chemical identification of an object and the construction of its elemental map of the surface and volume. Materials and methods. The physical principles of the XPS method operation, which determine its record high qualitative and quantitative accuracy, are considered, a description of one of the most highly efficient X-ray photoelectron spectrometers Escalab 250 Xi, features of its operation and methods of adaptation for the study of rocks and archaeological artifacts are given. A special methodological advantage is the possibility of sample preparation and research under ultrapure conditions of ultrahigh vacuum. Results. XPS spectra were obtained in a wide range of photoelectron binding energies, which makes it possible to cover a fairly wide range of chemical elements that make up rocks and archaeological artifacts. With a high degree of spatial locality – at the level of 30 μm – elemental maps of the objects under study were built. Using the additional advantage of the method, based on the analysis of the energy position and the shape of the photoelectron spectral line, the chemical states of the elements that make up the samples were determined. Discussion. The obtained results of high-precision chemical analysis, combining both the general composition of the elements of the test sample as a whole and their spatial distribution with a high degree of locality, make it possible to achieve greater unambiguity in the identification of the objects under study compared to currently used analysis methods. Such high accuracy makes it possible to establish a correspondence between the composition of the rock and the archaeological artifact from the same area. The non-destructive nature of the XPS method, combined with ultrapure analysis conditions, makes it possible to ensure the safety of often unique objects. Conclusion. As a result of the study, it was shown that the XPS method can be quite effectively used for high-precision qualitative and quantitative analysis of rocks and archaeological artifacts, which is achieved both by the features of the method itself and by sample preparation and study of materials in ultrapure conditions of ultrahigh vacuum. The advantage of the method is the combination of a number of possibilities, such as not only the elemental, but also the chemical composition of objects, as well as the possibility of chemical mapping of the surface and analysis of the depth of the object with high spatial resolution. The research results can be used in solving a wide range of problems – from archeology to the development of mountainous areas, in particular, solving environmental problems by developing a scientific reserve for creating effective geochemical barriers. Further research should be focused on the development of techniques for adapting the XPS method to obtain three-dimensional tomographic models of the studied objects, which will improve the quality of their identification, in particular, from the point of view of geology and archeology.

Electrochemical Dopamine Detection Using Palladium/Carbon Nano Onion Hybrids

In the given study, palladium-decorated carbon nano-onion nanostructures (Pd/CNO) were used as an electrochemical catalyst for detecting dopamine (DA). The physicochemical properties of the Pd/SO3H/CNO-based catalysts were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) methods. Pd/SO3H/CNO inks were dropped cast on a glassy carbon electrode (GCE) to prepare the electrochemical DA sensors. The sensor performance was performed using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The electroanalytical results indicated a LOD value of 2.44 M and the linear range of the sensors were found to be between 10 and 400 M DA. The enhanced electrocatalytic activity toward DA is attributed to the high active surface area, conductivity of CNO and the high electrocatalytic property of Pd. The results suggest that Pd/SO3H/CNO nanostructures can be used to detect electrochemical DA sensors with high selectivity, sensitivity, and low LOD.