X-ray Photoelectron Spectroscopy Spectra Research Articles

Unlocking the Electrocatalytic Behavior of Cu2MnS2 Nanoflake-Anchored rGO for the Oxygen Evolution Reaction in an Alkaline Medium.

A catalyst of the oxygen evolution reaction (OER) that is viable, affordable, and active for effective water-splitting applications is critical. A variety of electrocatalysts have been discovered to replace noble metal-based catalysts. Of these, transition metal-based sulfides are essential for incorporating carbonaceous materials to improve electrical conductivity, resulting in better electrocatalytic performance. Our study illustrates the synthesis of Cu2MnS2 (CMS) nanoflakes and their different rGO composites (10 to 40 wt %) via a hydrothermal technique for an effective water oxidation reaction. The X-ray diffraction pattern reveals that the prepared Cu2MnS2 nanoflakes exhibit a cubic crystal structure. The high-resolution scanning electron microscopy and the high resolution transmission electron microscopy images corroborate the formation of the nanoflake-like morphology of Cu2MnS2 with the strong interaction of rGO. The selected area electron diffraction analysis pattern reveals a polycrystalline nature. The Fourier transform infrared spectrum shows the existence of a metal sulfur vibrational band at 590 cm-1, and Raman analysis infers the presence of rGO. The X-ray photoelectron spectroscopy spectra reveal the oxidation states of the elements present in the samples. Using Brunauer-Emmett-Teller analysis, the surface area of CMS-20 is found to be 117.04 m2/g. The measured OER overpotentials using linear sweep volammetry and the values are 380, 370, 340, 376, and 400 mV at 10 mA/cm2 for CMS, CMS-10, CMS-20, CMS-30, and CMS-40, respectively, and the corresponding Tafel slope values are 179, 158, 149, 206, and 240 mV/decade, respectively. The electrochemical active surface area is estimated using cyclic voltammetry for all of the catalysts, where CMS-20 showed a larger surface area. Also, the same catalyst exhibits good stability for ∼24 h at a constant potential, which is confirmed via chronoamperometry. Thus, combining transition metal-based sulfides with carbonaceous materials indicates improved catalytic behavior for the preparation of high-performance OER electrocatalysts. Overall, the prepared CMS-20 performed as an efficient OER electrocatalyst and can be utilized for practical applications in energy conversion.

XPS Binding Energy Shifts in 2D Ti3C2Tz MXene go largely Beyond Intuitive Explanations: Rationalization from DFT Simulations and Experiments.

MXenes are prototypes of surface tunable 2D materials with vast potential for properties tuning. Accurately characterizing their surface functionalization and its role in electronic structure is crucial, X-ray photoelectron spectroscopy (XPS) being among the go-to methods to do so. Despite extensive use, XPS analysis remains however intricate. Focusing on the benchmark MXene Ti3C2Tz, Density Functional Theory (DFT) calculations of core-level binding energy shifts (BE.s.) are combined with experiments in order to provide a quantitative interpretation of XPS spectra. This approach demonstrates that BE.s. are driven by the complex interplay between chemical, structural, and subtle electronic structure effects preventing analysis from intuitive arguments or comparison with reference materials. In particular, it is shown that O terminations induce the largest BE.s. at Ti 2p levels despite lower electronegativity than F. Additionally, F 1s levels show weak sensitivity to the F local environment, explaining the single contribution in the spectrum, whereas O 1s states are significantly affected by the local surface chemistry. Finally, clear indicators of surface group vacancies are given at Ti 2p and O 1s levels. These results demonstrate the combination of calculations with experiments as a method of the highest value for MXenes XPS spectra analysis, providing guidelines for otherwise complex interpretations.

A mechanism study of type i corrosion on the surface of ancient tin rich bronzes

This study compares the surface patina of ancient tin rich bronze with pure hydrothermally synthesized SnO2 nanoparticles using various analytical techniques, including metallographic microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy. The primary crystalline component of the patina consists of approximately 5 nm SnO2 nanoparticles, which closely resemble pure SnO2, indicating their comparability. Cu was also detected in the patina; however, it did not form crystalline structures. The X-ray diffraction results showed a shift in the patina’s peak, suggesting the infiltration of Cu into the SnO2 lattice, which compromises its crystallinity. In comparison to synthetic SnO2, the X-ray photoelectron spectroscopy spectra of the patina revealed novel peaks corresponding to both Cu and O, indicating the presence of Cu−O−Sn bonding—a characteristic feature of type-I patina. This suggests that the primary structure of type-I patina consists of crystalline SnO2 nanoparticles, with a limited amount of Cu integrated into its lattice configuration. The concentration of Cu within the SnO2 crystal units is restricted, leading primarily to the formation of amorphous Cu2O in conjunction with Sn. The presence of Sn enhances the structural stability of Cu2O, facilitating its incorporation while inhibiting the crystallization of Cu2O. However, when the Sn concentration is insufficient, an inadequate Cu–O−Sn amorphous phase may form, allowing for the potential crystallization of Cu2O.

A robust 3D nanostructured composite polymer electrolyte with novel dual-ion channels toward solid-state sodium metal batteries

The high energy density and low cost of sodium metal batteries enable them to be the rising star of next-generation batteries. However, the growth of sodium dendrites and the high activity of sodium metal may lead to significant safety risks for liquid sodium metal batteries. Composite polymer electrolytes (CPEs), which combine the advantages of inorganic solid-state electrolyte and solid-state polymer electrolytes, have become a promising candidate to replace liquid electrolytes. In this study, a novel Na-beta-Al2O3/polyacrylonitrile (PAN) CPE with a 3D network nanostructure (NAP) has been synthesized by electrospinning method. NAP membrane provides synergistic dual-ion channels for the migration of sodium ions, exhibiting ionic conductivity of 7.22 × 10−4 S cm−1, a sodium-ion transport number of 0.73, and an electrochemical stabilization window as high as 4.92 V. Compared with pure PAN, NAP presents enhanced mechanical strength, superior electrochemical properties and interfacial stability. NAP-based sodium symmetric cell achieves stable plating and stripping for 800 h. At room temperature, the capacity retention ratios of NAP-based Na3V2(PO4)3//Na cell are 92.02 % (0.2C, 200 cycles) and 73.10 % (0.5C, 1000 cycles), respectively. The capacity retention is 72.49 % after 250 cycles at 0.5C and a high temperature of 60 ℃. X-ray photoelectron spectroscopy spectra indicate that solid electrolyte interphase formed in NAP-based battery contains higher NaF component, R–(CO)O–Na content and interfacially favorable organic components, which are beneficial to accelerate the sodium-ion transfer at the interface. This work provides new insights into the construction of 3D nanostructured CPEs with fast ion transport for solid-state sodium metal batteries.

An in-depth study of the synthesis of ReSe2 for anisotropic Raman characteristics

Abstract Two-dimensional transition metal dichalcogenides (TMDs) have received more interest for their potential role in future electronic and optoelectronic applications. Unlike other TMDs, Rhenium diselenide (ReSe2) stands out for its distinctive anisotropic growth characteristics. These unique features arise from its low lattice symmetry and interlayer decoupling, this has sparked significant interest among researchers. Previous research has indicated the presence of various growth patterns, including dendritic formations and structures resembling flowers. In this study, we effectively produced ReSe2 using the ‘Tilting Boat’ method to achieve growth on a 21 μm scale. Through precise manipulation of the growth conditions, we successfully attained flakes of 21 μm scale in comparison to prior findings. Moreover, we successfully produced a variety of shapes, including triangles, diamonds, and hexagons, on 1 × 1 cm2 Si/SiO2 substrates. Furthermore, we achieved the successful production of a continuous ReSe2 film on a 1 × 3 cm2 Al2O3 substrate. We verified the distinct anisotropic properties of ReSe2 via Raman Spectroscopy. Furthermore, we acquired three-dimensional visual representations of ReSe2 flakes and continuous films via SEM measurements. By employing EDS data and analysing x-ray photoelectron spectroscopy spectra, we have established a compositional ratio of 1:2 for Re and Se, which aligns with the MX2 structure. This confirmation indicates the successful synthesis of high-quality ReSe2 flakes.

Synthetic and natural antibacterial carbon adsorbents for clinical nuclear waste management

Patients undergoing high-dose radioiodine ablation (RAI) therapy in Nuclear Medicine Department need to be isolated in a special designed ward for a few days. Large amount of clinical radioactive wastewater from patient body is produced during high-activity RAI therapy. The radioactive wastewater needs to store in a delay tank until the radioactivity decayed below acceptable limit before being discharged and indirectly limit the patient admission and treatment. This study is to propose an alternative antibacterial adsorbent for I-131 extraction from clinical radioactive wastewater at the nuclear medicine department using graphene oxide silver (GOAg) and bamboo activated carbon (BAC). The synthesised adsorbents and their sediments (filtered sample) were analysed using field emission scanning electron microscopy (FESEM) for morphological analysis and analysed using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). XPS spectra for C 1s adsorbents show intensity peaks at 284.45 eV (C=C) and 285.3 eV (C–C) for GOAg and its sediments, and 284.35 eV (C–C), 287.00 eV (C=O), and 290.07 eV (π–π∗ transitions) for BAC and its sediments. FTIR spectra reveal various functional groups of adsorbents: C=C (1637.50772 cm−1), C=O (1340.48041 cm−1), and C–O–C (1031.88060 cm−1) for GOAg and its sediments, and C=C (1635.57897 cm−1), C–C (1257.54421 cm−1), and C–O (1188.10925 cm−1) for BAC and its sediments. XRD patterns exhibit peaks at 2θ = 27.82°, 29.39°, 32.24°, and 46.22°, which can be attributed to the (002) diffraction plane, (220) crystallographic plane, (111) plane of Ag2O, and (200) crystallographic plane, respectively, for GOAg and its sediments. Meanwhile, the peaks at 2θ = 26.56° and 42.41°, which correspond to (002) and (100) planes, respectively, for BAC and its sediments. The d-spacing and the crystallinity index of each adsorbent were also determined. The estimation of the remaining β− particles during the adsorption of I-131 was carried out using PHITS. The finding of this study is beneficial for alternative radionuclide extractions technique from clinical radioactive wastewater in nuclear medicine.

Plasma treatment on flame soot: view from nanostructure and reactivity of soot

In recent years, the use of plasma for pollutant emission control has an expected potential. In this study, soot particles from flames were sampled from an ethylene inverse diffusion flame, which were placed in a self-designed dielectric barrier discharge plasma device for reaction treatment. The nanostructure and oxidation reactivity of soot particles after plasma treatment were evaluated by transmission electron microscopy, Raman spectroscopy, X-ray diffraction analysis and X-ray photoelectron spectroscopy. With 16 kV, 2.5 kHz as an example, with the treatment of plasma, the fringe length decreases (1.3% and 9.6%), and the fringe tortuosity increases (1.1% and 8.7%) in both high-maturity and low-maturity soot particles, which means that the oxidation activity of soot is enhanced after plasma discharge. Raman spectra, X-ray diffraction analysis spectra and X-ray photoelectron spectroscopy spectra have confirmed this phenomenon, especially the oxidation activity of soot particles under the action of plasma at high maturity is more obvious. It is worth noting that the enhancement of soot oxidation activity after plasma discharge has certain limitations, that is, the oxidation activity will not continue to increase after it is enhanced to a certain intensity, which may be related to the selection of Ar as the atmosphere gas.

Epitaxial growth and characterization of copper gallate (CuGa2O4) thin films by pulsed laser deposition

High-quality crystalline copper gallate (CuGa2O4) thin films were grown on c-plane sapphire substrates using the pulsed laser deposition (PLD) technique by optimizing the growth parameters (i.e., temperature, oxygen chamber pressure, and laser energy density). The obtained XRD patterns validated that the preferred orientation of the crystalline CuGa2O4 thin film is along the [111] direction, and the crystallinity of the films improved with increasing substrate temperature while maintaining a constant O2 pressure, as assessed by measuring the full width at half maximum (FWHM) of the prominent (222) plane. Reducing the oxygen pressure leads to the emergence of β-Ga2O3 peaks rather than the CuGa2O4 peaks due to the incomplete oxidation of copper (Cu). Subsequent XRD phi (φ) scans revealed a sixfold rotational symmetry of CuGa2O4 and a 30° epitaxial relationship between the film and the sapphire substrate. X-ray photoelectron spectroscopy (XPS) spectra confirmed the presence of Cu1+, Cu2+, and Ga3+ oxidation states in the films. Increasing laser energy density resulted in the complete oxidation of Cu and an increase in the film thickness from 51.8 nm to 183.4 nm. The direct bandgap of CuGa2O4 films was determined to be approximately 4.50 eV by analyzing the UV–Vis absorbance spectra using the Tauc equation. The refractive index was found to be approximately 2.05 ± 0.01 based on the spectroscopic ellipsometry data. While the impact of increasing laser energy density was negligible on the parameters such as crystal structure, rotational symmetry, oxidation states of gallium (Ga), oxygen (O), bandgap, and refractive index of CuGa2O4 thin film, notable alterations in the oxidation state of Cu and film thickness were observed. The surface roughness (Rrms) measured from AFM images showed a strong correlation with the values derived from ellipsometry analysis.

Activated carbon from agricultural industry waste for use as an adsorbent of sulfamethazine: Fascinating and environmentally friendly process

Lignocellulosic wastes have garnered interest in activated carbon (AC) production owing to their abundance and cost-effectiveness. This research utilized coffee husk as a precursor for AC. The methodology involves impregnating the waste with varying proportions of phosphoric acid (H3PO4), 1:1 and 1:3 (masswaste:massH3PO4), and activation in a microwave oven, with different power and activation times. The N2 adsorption/desorption results demonstrated high surface areas (SBET) for the ACs. The optimized AC (C1:3-1000-10) was obtained using a time of 10 min, high impregnation ratio, and power, resulting in an SBET of 1200 m2 g−1. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra confirmed the presence of functional groups, such as hydroxyl and ester, on the AC surface. Adsorption tests with sulfamethazine (SMZ) showed a 225 mg g−1 remotion capacity, highlighting the waste potential for sustainable and economical AC production. This underscores the importance of optimizing activation parameters to enhance performance and application versatility in AC production from lignocellulosic sources.

Stabilization of arsenic-cadmium co-contaminated soil with the iron-manganese sludge derived amendment: Effects and mechanisms

An iron-manganese sludge-derived amendment was proposed to remediate arsenic (As) and cadmium (Cd) co-contaminated soil, with a strong adsorptive capacity across pH 4 to 10. The Langmuir model defined maximum adsorption at 78.17 mg/g for As(III), 110.48 mg/kg for As(V), and 65.77 mg/g for Cd(II). The X-ray photoelectron spectroscopy (XPS) spectra provided insights into the chemical interactions: As was predominantly complexed or ligand exchanged with iron(hydr)oxides. In contrast, cadmium exhibited a tendency to bond with acylamino and carboxyl groups, in addition to the ferric hydroxyl groups. Notably, 42.15% of the adsorbed As(III) was oxidized into As(V) by Mn(IV) oxides present in the amendment. The soil-verification experiment demonstrated that an amendment dosage of 40 g/kg was efficacious in reducing the leaching concentration of As and Cd to maintained below the safety thresholds of 0.1 mg/L and 0.01 mg/L, respectively, for pH levels 4 to 11, meeting the Chinese Surface Water Quality Standard V (GB3838-2002). After the stabilization, the exchangeable fractions of As and the acid-soluble fractions of Cd were significantly reduced, with these elements being transformed into more stable forms. The amendment maintained the soil's neutral pH and adjusted the soil physicochemical properties. This article presents a holistic approach by examining the organic-inorganic composite of iron-manganese oxides with polyacrylamide, modified as a stabilizing amendment for As and Cd co-contaminated soil. This innovative amendment adeptly navigates the previously conflicting stabilization mechanisms for anionic and cationic metals. Offering dual advantages, the amendment not only remediates soil but also addresses the disposal of waste, presenting a win-win solution for environmental management.

Benchmark Study of Core-Ionization Energies with the Generalized Active Space-Driven Similarity Renormalization Group.

X-ray photoelectron spectroscopy (XPS) is a powerful experimental technique for probing the electronic structure of molecules and materials; however, interpreting XPS data requires accurate computational methods to model core-ionized states. This work proposes and benchmarks a new approach based on the generalized active space-driven similarity renormalization group (GAS-DSRG) for calculating core-ionization energies and treating correlation effects at the perturbative and nonperturbative levels. We tested the GAS-DSRG across three data sets. First, the vertical core-ionization energies of small molecules containing first-row elements are evaluated. GAS-DSRG achieves mean absolute errors below 0.3 eV, which is comparable to high-level coupled cluster methods. Next, the accuracy of GAS-DSRG is evaluated for larger organic molecules using the CORE65 data set, with the DSRG-MRPT3 level yielding a mean absolute error of only 0.34 eV for 65 core-ionization transitions. Insights are provided into the treatment of static and dynamic correlation, the importance of high-order perturbation theory, and notable differences from density functional theory in the predicted energy ordering of core-ionized states for specific molecules. Finally, vibrationally resolved XPS spectra of diatomic molecules (CO, N2, and O2) are simulated, showing excellent agreement with experimental data.

Regulated Photocatalytic CO2-to-CH3OH Pathway by Synergetic Dual Active Sites of Interlayer.

Herein, composites of nanosheets with van der Waals contacts are employed to disclose how the interlayer-microenvironment affects the product selectivity of carbon dioxide (CO2) photoreduction. The concept of composites of nanosheets with dual active sites is introduced to manipulate the bonding configuration and promote the thermodynamic formation of methanol (CH3OH). As a prototype, the CoNi2S4-In2O3 composites of nanosheets are prepared, in which high-resolution transmission electron microscopy imaging, X-ray photoelectron spectroscopy spectra, and zeta potential tests confirm the presence of van der Waals contacts rather than chemical bonding between the In2O3 nanosheets and the CoNi2S4 nanosheets within the composite. The fabricated CoNi2S4-In2O3 composites of nanosheets exhibit the detection of the key intermediate *CH3O during CO2 photoreduction through in situ Fourier transform infrared spectra, while the In2O3 nanosheets and CoNi2S4 nanosheets alone do not show this capability, further verified by the density functional theory calculations. Accordingly, the CoNi2S4-In2O3 composites of nanosheets show the ability to produce CH3OH, whereas the CoNi2S4 and In2O3 nanosheets solely generate carbon monoxide products from CO2 photoreduction.

MoⅣ boosted carrier density of MoO3-X for surface-enhanced Raman spectroscopy

Molybdenum oxides (MoO3-X) with the same surface plasmon resonance (SPR) effect as Au/Ag, and occupies an irreplaceable value in SERS detections. MoO3-X SERS substrates with oxygen-rich defects tend to show better SERS performance, but the preparation and characterization of tunable O defects remain challenging. It cannot be ignored that the oxidation state of metal cations is also influenced by O defects. Here, a series of MoO3-X SERS sensors with regulable Mo valence state were fabricated using magnetron sputtering technology. By changing the Mo sputtering power and the O2/Ar2 ratio, the Mo/O element ratio of the substrate can be easily regulated to readjust the O defects. The X-ray Photoelectron Spectroscopy (XPS) and Raman spectra were performed to investigate the change and related relationship between Mo mixed valence state and SERS sensitivity. The abundant incompletely coordinated electrons produced by low valence MoⅣ act as free carriers, increasing the free carrier density of MoO3-X substrates, which is beneficial for the SERS effect. It has also been proven by Hall effect measurement. The SERS measurement shows that the enhancement factor (EF) reached 3.70 × 105, which is exceedingly close to Au/Ag. The MoO2.5 substrate also exhibited a repeatable and consistent response, high stability, and repeatability, which proves the splendid application potential in complex environments.

Ligand-free Ni-Cu bimetallic nanocatalyst: Laser synthesis, characterization and its high performance for borohydride assisted catalytic reduction of 4-nitrophenol

In the present work, nickel and copper bimetallic nanoparticles with three different concentration ratios of 70:30, 50:50, and 30:70 were synthesized by laser ablation of Ni and Cu in deionized water. The suitability of Ni-Cu bimetallics as nanocatalysts was investigated in the catalytic reduction of pollutant 4-nitrophenol. The nanocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV–Vis) spectroscopy. The morphology using SEM and TEM indicated that Cu had an elongated or flake-like structure, whereas Ni had a quasi-spherical structure. XPS investigation has been performed to study the elemental composition and chemical states near-surface regions of the generated Ni-Cu bimetallic nanoparticles. XRD and XPS confirm high oxidation of Cu to CuO with approximately no residual Cu metal. However, the XRD patterns did not show complete Ni oxidation to NiO, confirming the presence of a Ni dopant part in the Ni-Cu samples. The behavior of the photoelectron peaks in the XPS spectra suggested that the Ni-Cu nanocomposites exhibited surface charge transfer. Pulsed laser ablation developed ligand-free Ni-Cu nanoparticles, which affected the structure and catalytic properties. The nanocatalyst for 50:50 of Ni and Cu had the highest rate constant, corresponding to the shortest time required to achieve 100 % conversion/reduction of the pollutant dye. The apparent synergistic effect between Ni and Cu is clearly dictated by the amount of Cu embedded in the nanocomposites, with this becoming a key factor in lowering the band gap energy values. Overall, the surface charge transfer rate can enhance the catalytic performance by tuning the Ni and Cu concentrations.

Low-energy argon ion beam irradiation for the surface modification and reduction of graphene oxide: Insights from XPS

Developing environmentally friendly methods for reducing graphene oxide (GO) is essential. This study investigates the surface modification and reduction of GO films using 200 eV argon ion (Ar+) beam irradiation. X-ray Photoelectron Spectroscopy (XPS) analysis reveals significant chemical changes on the GO surface. GO was irradiated with a 200 eV Ar+beam for varying times (0–80 s). XPS survey spectra showed the presence of carbon and oxygen, with an increasing carbon atomic percentage over time. High-resolution XPS spectra of C 1s revealed peaks corresponding to sp2, C–OH, O–C–O, CO, and O–CO bonds. In the O 1s spectra, CO, O–C–O, and C–OH groups were observed. Upon irradiation, the CO peak consistently decreased, the O–C–O peak fluctuated, and the C–OH peak increased, indicating effective reduction of CO groups, dynamic changes in O–C–O functionalities, and the formation of additional C–OH groups. The C/O ratio increased from ∼2.4 to 2.7, underscoring the reduction process and enhanced carbon content. This method proves to be an efficient approach for producing reduced graphene oxide (rGO) with improved properties for advanced applications.

Efficient hole transport layers for silicon heterojunction solar cells by surface plasmonic modification in MoOx/Au NPs/MoOx stacks

This study explores the integration of Au nanoparticles (NPs) into molybdenum oxide (MoOx) thin films to form a MoOx/Au NPs/MoOx (MAM) stack. This stack serves as a hole transport layer (HTL) in silicon heterojunction solar cells, aiming to address the challenges of safety concerns and inefficient carrier transport. Ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy spectra demonstrate that the incorporation of Au NPs notably raises the work function of MAM to 5.85 eV and stabilize Mo6+ concentrations at 94.07%. In addition, Au NPs effectively act as a shield against detrimental interactions with Ag, thereby improving the interfacial stability between the back electrode and HTL. This strategic enhancement facilitates the formation of surface plasmon polaritons, reduces the contact resistance to 41.19 mΩ cm2, and boosts the quantum efficiency by injecting hot electrons and intensifying the surface electric field. These advancements lead to a significant enhancement in the fill factor and short-circuit current, leading to the development of a heterojunction solar cell with an increased efficiency (Eff) from 19.81% to 22.03%. This investigation underscores the transformative potential of engineered nanomaterials in elevating the performance and stability of photovoltaic devices, promoting the wider adoption of renewable energy technologies.

Boosting O2 activation by internal electric field regulation in vacancy-enhanced S-scheme heterojunction for efficient degradation of bisphenol A

The photocatalytic molecular oxygen (O2) activation is hindered by the weak O2 adsorption capacity and obstacles to electron transfer. Herein, a vacancy-enhanced BiOI/g-C3N4 S-scheme heterojunction was designed to enhance the O2 adsorption capacity and accelerate electron transfer in water treatment. The density functional theory calculation (DFT), in-situ irradiation X-ray photoelectron spectroscopy (XPS) spectra and experiments demonstrate that the S-scheme charge transfer mechanism. And the introduction of N vacancies in g-C3N4 can adjust the electronic structure, strengthen the internal electric field in S-scheme heterojunction, thereby broadening the light response range and further improving the separation rate of photoinduced electron-hole pairs. Besides, the presence of N vacancies can function as the active sites for the adsorption of O2 and facilitate the capture of electrons, promoting the generation of superoxide radicals (•O2−). Thanks to the synergistic effect of the S-type charge transfer route with N vacancies in g-C3N4, degradation rate of bisphenol A (BPA) for BCN-680 increases to 0.0433 min−1, which is 1.86 and 10.56 times higher than BiOI and CN-680. This work presents a valuable method for O2 activation through designing the S-scheme heterojunction with abundant active sites by vacancy construction.

Investigating the impact of strontium doping on neodymium manganite Nanoperovskites: Analysis of structural, optical, and dielectric properties

Nd1-xSrxMnO3 (x = 0, 0.3, 0.5, 0.7) nanoperovskites were fabricated through combustion process, a low-cost technique in contrast to the vacuum methodologies for growth. The singular phase orthorhombic Pbnm crystallized for x = 0 to 0.5; nevertheless, both orthorhombic and monoclinic phases were discerned at x = 0.7. Employing X-ray photoelectron spectroscopy (XPS) spectra, the surface chemistry has been conducted, encompassing the intricate parameters associated with the oxygen reduction reaction (ORR).The BDS analysis at ambient temperature, encompassing the frequency span from 1 Hz to 1000 KHz, elucidates various facets of dielectric properties. Elevated dielectric constants at the low-frequency spectrum are explained by the Maxwell–Wagner effect. With an escalation in doping concentration, there is a concurrent rise in the dielectric constant. The escalation in AC conductivity within the high-frequency domain conforms to Johnscher's universal power law, whereas the ramifications of electrode polarization are delineated through a log-log representation.

Exploring Electrochemical Sensing for Fungicide Detection: Utilization of Newly Synthesized Oligomers.

The determination of thiabendazole is crucial for ensuring food safety, environmental protection, and compliance with regulatory standards. Accurate detection helps prevent harmful exposure, ensuring the safety of agricultural products and safeguarding public health. Therefore, this study investigates the electrochemical sensing capabilities of newly synthesized oligo 3-amino-5-mercapto-1,2,4-triazole (oligo AMTa) using hydrogen tetrachloroaurate (III) (HAuCl4) as an oxidizing agent at room temperature for thiabendazole (TBZ) detection, employing a simple electrode fabrication process. The prepared oligo AMTa was thoroughly characterized using UV-visible spectroscopy, scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution mass spectroscopy (HR-MS), and Fourier-transform infrared spectroscopy (FT-IR) to confirm its oligomerization structure and properties. The IR spectrum of oligo AMTa reveals a new peak at 1449 cm-1, indicating the conversion of -NH2 groups to -N=N- groups during oligomerization, unlike AMTa. Additionally, the disappearance of the -SH group peak at 2615 cm-1 in oligo AMTa suggests an S-S linkage involvement in the oligomerization process. In the oligo AMTa XPS spectrum, the presence of C=N is displayed by a small peak at 287.3 eV, and oligomerization via -NH and N=N is confirmed by the lack of a 284.0 eV peak for C-C or C=C. Gold nanoparticle formation is not demonstrated by the 84.8 eV peak, which implies that the gold atom is not in the Au0 state. The HR-MS spectrum of oligo AMTa shows a peak at m/z 564.08, indicating a chain of five monomers, and another peak at m/z 435.03, confirming the presence of a tetrameric form of AMTa. After that, the GC electrode was directly linked to the oligo AMTa by the potentiodynamic method. SEM, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) were all employed to confirm the fabrication of oligo AMTa. The SEM image illustrates the formation of a particlelike structure with a uniform size of the oligomer after cycling in 0.1 M H2SO4. After electrocycling, the size of the oligomer was reduced from 2.6 μm to 30 nm. The oligo AMTa-modified electrode possesses the highest electroactive surface area and electrical conductivity due to several key factors. First, the presence of amino (-NH2) and thiol (-SH) functional groups in AMTa enhances the surface coverage and density of electroactive sites, increasing the electroactive surface area. Additionally, the conjugated structure of AMTa facilitates efficient electron transfer, resulting in enhanced electrical conductivity compared to unmodified electrodes. Eventually, the electrochemical oxidation of TBZ occurred using the fabricated electrodes. The GC/oligo AMTa electrode exhibited a four-fold increase in oxidation current for TBZ compared to unmodified GC electrodes. This enhancement is due to the improved surface properties from the oligo AMTa modification, which significantly boosts TBZ adsorption through strong interactions like hydrogen bonding and π-π stacking. These interactions, along with the increased surface area and catalytic properties, facilitate effective electron transfer, resulting in a higher oxidation current. As an outcome, the film was employed to determine the sensitivity level of TBZ, and a LOD of 1.8 × 10-11 M (S/N = 3) was found. The straightforward method's practical utility was proven by measuring TBZ in tap water, water spinach, and pear juice samples. The comprehensive characterization of oligo AMTa provided insights into its interaction mechanisms with thiabendazole, contributing to the development of a reliable, cost-effective, and efficient sensor.

A low-cost and convenient route of fabricating GaN films with P-type mixed microcrystalline and amorphous structure deposited via Ga target of magnetron sputtering

GaN, a third-generation semiconductor, has gained widespread attention owing to its high temperature resistance, wide bandgap, and high critical breakdown electric fields. Magnetron sputtering has a broad potential in the field of low-cost growth of GaN on account of high efficiency, superior quality, and convenient operation. However, challenges caused from the pure Ga targets with a huge refrigeration system need to be resolved for wide practices. Here, a new and cost-effective Ga target for magnetron sputtering was fabricated by utilizing the wetting properties of CuGa2 and Ga. Mixed microcrystalline and amorphous GaN films were obtained via reactive magnetron sputtering employing the Ga target. The average deposition rate is about 1.68 nm/min, and the average roughness is ∼7.45 ± 0.26 nm under 100 W of sputtering power. In addition, the sputtered GaN films were found to be wide-bandgap and p-type semiconductors with high transmittance, as revealed by x-ray photoelectron spectroscopy and absorption spectra. The GaN films display a bandgap of ∼3.60 eV and a transmittance exceeding 88.5% in the visible range. Furthermore, field-effect transistors and metal–semiconductor–metal photodetectors have been fabricated using the obtained GaN films, demonstrating favorable response characteristics. The prospects of microcrystalline/amorphous GaN films in sensing, power devices, and flexible electronics were forecasted. Overall, a low-cost and pervasive route of target fabrication process expands the possibilities of using low melting point metals in magnetron sputtering.