Showing papers on "Raman spectroscopy published in 2023"
TL;DR: In this paper , a ternary piezoelectric catalyst MoOx/ZnS/ ZnO (MZZ) was synthesized by a one-step method.
Abstract: This paper synthesized a new type of ternary piezoelectric catalyst MoOx/ZnS/ZnO (MZZ) by a one-step method. The catalytic degradation of Rhodamine B (RhB) solution (10 µg/g, pH = 7.0) shows that the composite catalyst has excellent piezoelectric catalytic activity under ultrasonic vibration (40 kHz). The piezoelectric degradation rate of the optimal sample reached 0.054 min−1, which was about 2.5 times that of pure ZnO. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) technologies were used to analyze the structure, morphology, and interface charge transfer properties of the MZZ piezocatalysts. The results showed that the composite catalyst may have a core-shell structure. ZnS is coated on the surface of ZnO, while MoOx adheres to the surface of ZnS. This structure endowed MZZ larger specific surface area than ZnO, which benefits the RhB adsorption. More importantly, the formed heterojunction structure between ZnS and ZnO promotes the separation of positive and negative charges induced by the piezoelectric effect. MoOx species may act as a charge trap to further promote more carriers to participate in the reaction. In addition, MoOx may also be beneficial in adsorbing dyes. Active species capture experiments show that superoxide radicals and holes are the main active species in piezoelectric catalytic reactions on MZZ catalysts.
62 citations
TL;DR: Fe3C/Fe decorated N-doped magnetic carbon materials were successfully fabricated via facile one-pot calcination of MIL-88B(Fe) with a green precursor of melamine as mentioned in this paper .
Abstract: Fe3C/Fe decorated N-doped magnetic carbon materials (denoted as Fe3C/Fe@N-C-x) were successfully fabricated via facile one-pot calcination of MIL-88B(Fe) with a green precursor of melamine. Benefiting from the co-existence of sp2-hybridized C–π moieties, oxygen-containing groups (CO and O–CO), N-doping species and ferreous nanoparticles (FNPs), the as-obtained Fe3C/Fe@N-C-9 exhibited excellent activation of peroxymonosulfate (PMS) for ultrafast elimination of various emerging organic contaminants with high mineralization capacities. Inspired by the unique nanotube morphology and encapsulation of FNPs, the Fe3C/Fe@N-C-9 possessed trace Fe leaching and can be magnetically separated for an easy recycling. Combining with competitive radical scavenging tests, electron spin resonance (ESR), electrochemical analysis and in-situ Raman spectra, the singlet oxygen (1O2) and electron-transfer can be accounted for the organic pollutant removal. Because of that, the Fe3C/Fe@N-C-9 exhibited good resistance to inorganic anions and natural organic matters (NOMs). It was fascinating that Fe3C/Fe@N-C-9 achieved satisfactory treatment efficiency for real pharmaceutical wastewater.
37 citations
TL;DR: In this paper , the nitrogen doped lutetium hydride (LuH2±xNy) with a dark-blue color and a structure with the space group of [Formula: see text] evidenced by x-ray diffraction was obtained by using a high pressure and high temperature synthesis technique.
Abstract: Recently near-ambient superconductivity was claimed in nitrogen-doped lutetium hydride1. This stimulates a worldwide interest about exploring room temperature superconductivity under low pressures. By using a high pressure and high temperature synthesis technique, we have successfully obtained the nitrogen doped lutetium hydride (LuH2±xNy) with a dark-blue color and a structure with the space group of [Formula: see text] evidenced by x-ray diffraction. This structure is the same as that reported in ref. 1, with a slight difference in lattice constant. The Raman spectroscopy also shows similar patterns between our samples and that in ref. 1. The energy dispersive X-ray spectroscopy (EDS) confirmed the existence of nitrogen in the samples. At ambient pressure, we witness a metallic behavior from 350 down to 2 K. By applying pressures from 2.1 to 41 GPa, we observe a gradual color change from dark-blue, to violet, to pink-red. By measuring the resistance at pressures from 0.4 to 40.1 GPa, we have seen a progressively improved metallic behavior without showing superconductivity down to 2 K. Temperature dependence of magnetization under high pressures shows a very weak positive signal between 100 and 320 K, and the magnetization increases with magnetic field at 100 K, all these are not expected for superconductivity at 100 K. Thus, we conclude the absence of near-ambient superconductivity in this nitrogen-doped lutetium hydride under pressures below 40.1 GPa.
25 citations
TL;DR: In this paper , a mesoporous coating structure was created by employing template molecules such as surfactant and their subsequent removal allowing selective screening based on the size of analyte molecules.
18 citations
TL;DR: Raman spectroscopy is now an extremely important technique for the analysis of carbon-based materials and it can be used to give a unique insight into characterising many aspects of the microstructure of these materials, including orientation, number of layers, defects and doping, enabling standardisation and quality control as discussed by the authors .
17 citations
TL;DR: In this article , the authors report new directions and perspectives of SERS and TERS, mainly from the viewpoint of combining their mechanism and application studies, and discuss four main topics: (1) nanometer to subnanometer plasmonic hotspots for SERS, (2) Ångström resolved TERS; (3) chemical mechanisms, i.e., charge-transfer mechanism of sERS and semiconductor-enhanced Raman scattering; and (4) the creation of a strong bridge between the mechanism studies and applications.
Abstract: Surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) have opened a variety of exciting research fields. However, although a vast number of applications have been proposed since the two techniques were first reported, none has been applied to real practical use. This calls for an update in the recent fundamental and application studies of SERS and TERS. Thus, the goals and scope of this review are to report new directions and perspectives of SERS and TERS, mainly from the viewpoint of combining their mechanism and application studies. Regarding the recent progress in SERS and TERS, this review discusses four main topics: (1) nanometer to subnanometer plasmonic hotspots for SERS; (2) Ångström resolved TERS; (3) chemical mechanisms, i.e., charge-transfer mechanism of SERS and semiconductor-enhanced Raman scattering; and (4) the creation of a strong bridge between the mechanism studies and applications.
15 citations
TL;DR: In this paper , a review of commonly applied in situ techniques, for instance, transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), and Xray absorption near-edge structure (XANES), and their applications on the representative cathode and anode materials with selected samples are summarized.
13 citations
TL;DR: In this article , vanadium pentoxide (V2O5) and reduced graphene oxide (reduced graphene oxide) composite were synthesized by a hydrothermal method and the prepared samples were characterized by X-ray diffraction (XRD), Xray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and UV-Vis spectroscopic analysis, etc.
Abstract: Semiconductor-based photocatalyst materials played an important role in the degradation of organic compounds in recent years. Photocatalysis is a simple, cost-effective, and environmentally friendly process for degrading organic compounds. In this work, vanadium pentoxide (V2O5) and V2O5/RGO (reduced graphene oxide) composite were synthesized by a hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, and UV-Vis spectroscopic analysis, etc. Raman analysis shows the occurrence of RGO characteristic peaks in the composite and different vibrational modes of V2O5. The band gap of flake-shaped V2O5 is reduced and its light absorption capacity is enhanced by making its composite with RGO. The photocatalytic degradation of methylene blue (MB) was studied using both V2O5 and V2O5/RGO composite photocatalyst materials. The V2O5/RGO composite exhibits a superior photocatalytic performance to V2O5. Both catalyst and light play an important role in the degradation process.
13 citations
TL;DR: In this article , a breakthrough on the specific capacitance and cyclic stability of supercapacitors based on N-Ti3C2@Ni3S4 nanocomposites was made.
12 citations
TL;DR: In this paper , a literature review on the properties and advanced characterization techniques of GMABs is conducted, and the main contribution of this investigation is the identification of the prominent trends and gaps in the current state of knowledge.
Abstract: Graphene is a carbon-based nanomaterial used in various industries to improve the performance of hundreds of materials. For instance, graphene-like materials have been employed as asphalt binder modifying agents in pavement engineering. In the literature, it has been reported that (in comparison to an unmodified binder) the Graphene Modified Asphalt Binders (GMABs) exhibit an enhanced performance grade, a lower thermal susceptibility, a higher fatigue life, and a decreased accumulation of permanent deformations. Nonetheless, although GMABs stand out significantly from traditional alternatives, there is still no consensus on their behavior regarding chemical, rheological, microstructural, morphological, thermogravimetric, and surface topography properties. Therefore, this research conducted a literature review on the properties and advanced characterization techniques of GMABs. Thus, the laboratory protocols covered by this manuscript are atomic force microscopy, differential scanning calorimetry, dynamic shear rheometer, elemental analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. Consequently, the main contribution of this investigation to the state-of-the-art is the identification of the prominent trends and gaps in the current state of knowledge.
11 citations
TL;DR: In this article , an ultrathin carbon-confined Nb12O29 material with rich oxygen vacancies was designed and synthesized to address the problems of low intrinsic electronic conductivity and structural stability.
Abstract: Given the inherent features of open tunnel-like structures, moderate lithiation potential (1.0-3.0 V vs Li/Li+), and reversible redox couples (Nb5+/Nb4+ and Nb4+/Nb3+ redox couples), niobium-based oxides with Wadsley-Roth crystallographic shear structure are promising anode materials. However, their practical rate capability and cycling stability are still hindered by low intrinsic electronic conductivity and structural stability. Herein, ultrathin carbon-confined Nb12O29 materials with rich oxygen vacancies (Nb12O29-x@C) were designed and synthesized to address above-mentioned challenges. Computational simulations combined with experiments reveal that the oxygen vacancies can regulate the electronic structure to increase intrinsic electronic conductivity and reduce the Li+ diffusion barrier. Meanwhile, the carbon coating can enhance structural stability and further improve the electronic conductivity of the Nb12O29 material. As a result, the as-prepared Nb12O29-x@C exhibits high reversible capacity (226 mAh g-1 at 0.1 A g-1), excellent high-rate performance (83 mAh g-1 at 5.0 A g-1), and durable cycling life (98.1% capacity retention at 1.0 A g-1 after 3000 cycles). The lithium storage mechanism and structural stability of Nb12O29-x@C were also revealed by in situ X-ray diffraction (XRD), ex situ X-ray photoelectron spectroscopy (XPS), and ex situ Raman spectroscopy. When applied as the anode of lithium-ion capacitors (LICs), the as-built LIC achieves high energy density (72.4 Wh kg-1) within the voltage window of 0.01-3.5 V, demonstrating the practical application potential of the Nb12O29-x@C materials.
TL;DR: In this article , the authors proposed a promising insertion-type anode for high mass loading anode with high performances, which achieved a high reversible capacity of 194 mA h g−1 at 0.1 A g −1 with a voltage of ≈ 0.37 V and an impressive cyclability with 128 m a h g − 1 over 2500 cycles at 1 A g− 1.
TL;DR: Li et al. as discussed by the authors developed a double-cation etching strategy to tailor the electronic structure of NiMoO 4 , where the prepared NiO 4 nanorods etched by H 2 O 2 reconstruct their surface with abundant cation deficiencies and lattice distortion.
Abstract: Abstract Rational reconstruction of oxygen evolution reaction (OER) pre-catalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis. Herein, we develop a double-cation etching strategy to tailor the electronic structure of NiMoO 4 , where the prepared NiMoO 4 nanorods etched by H 2 O 2 reconstruct their surface with abundant cation deficiencies and lattice distortion. Calculation results reveal that the double cation deficiencies can make the upshift of d -band center for Ni atoms and the active sites with better oxygen adsorption capacity. As a result, the optimized sample (NMO-30M) possesses an overpotential of 260 mV at 10 mA cm −2 and excellent long-term durability of 162 h. Importantly, in situ Raman test reveals the rapid formation of high-oxidation-state transition metal hydroxide species, which can further help to improve the catalytic activity of NiMoO 4 in OER. This work highlights the influence of surface remodification and shed some light on activating catalysts.
TL;DR: Pristine and Sr-doped TiO2 (1, 2.5% and 5%) nanoparticles were synthesized at low temperatures via an eco-friendly hydrothermal route for water splitting applications as mentioned in this paper .
Abstract: Pristine TiO2 and Sr-doped TiO2 (1%, 2.5% and 5%) nanoparticles were synthesized at low temperatures via an eco-friendly hydrothermal route for water-splitting applications. XRD, EDAX and Raman analysis were performed to analyze the crystallinity, purity and structure of the as-synthesized materials. TEM, SEM, BET and UV-DRS studies were carried out to elucidate the size, morphology, surface area and optoelectronic properties of the nanoparticles. High surface areas of 169, 182, 178 and 141.16 m2 g−1 for pristine TiO2 (12 ± 0.6 nm) and 1% (11.1 ± 0.6 nm), 2.5% (12.1 ± 0.6 nm) and 5% (13 ± 0.7 nm) Sr-doped TiO2 nanoparticles were obtained, respectively. One-percent Sr-doped TiO2 nanoparticles were found to be active photocatalysts, as they showed higher hydrogen production (26.30 mmolgcat−1). Furthermore, electrocatalysis was investigated for HER and OER in 0.5 N H2SO4 and 0.1 N KOH electrolytic solutions using calomel as a reference electrode, revealing that 1% and 5% Sr-doped TiO2 showed maximum current density for both HER (≈10 mA/cm2) and OER (≈2.49 mA/cm2), with an onset potential of 0.96 V for HER and 1.55 V for OER, and Tafel slopes of 84.09 and 91.60 mV/dec, respectively.
TL;DR: In this article , Ag, Fe co-doped TiO2 nanoparticles were prepared via a simple sol-gel method and the structural, morphological, and optical properties of the nanoparticles are characterized by various scientific techniques.
TL;DR: In this paper , the authors used Raman spectroscopy to study human hepatic tissue samples, and developed and validated a workflow for in vitro and intraoperative pathological diagnosis of liver cancer.
Abstract: Biopsy is the recommended standard for pathological diagnosis of liver carcinoma. However, this method usually requires sectioning and staining, and well-trained pathologists to interpret tissue images. Here, we utilize Raman spectroscopy to study human hepatic tissue samples, developing and validating a workflow for in vitro and intraoperative pathological diagnosis of liver cancer. We distinguish carcinoma tissues from adjacent non-tumour tissues in a rapid, non-disruptive, and label-free manner by using Raman spectroscopy combined with deep learning, which is validated by tissue metabolomics. This technique allows for detailed pathological identification of the cancer tissues, including subtype, differentiation grade, and tumour stage. 2D/3D Raman images of unprocessed human tissue slices with submicrometric resolution are also acquired based on visualization of molecular composition, which could assist in tumour boundary recognition and clinicopathologic diagnosis. Lastly, the potential for a portable handheld Raman system is illustrated during surgery for real-time intraoperative human liver cancer diagnosis.
TL;DR: In this article , a review of in-situ/operando Raman studies in probing different electrocatalytic systems is presented, where the authors systematically discuss the development, advantages, and configurations now available for applying these Raman techniques.
TL;DR: In this article , the ternary chalcopyrite CuInSe2 (CIS) nanosheets with different Zn doping content were synthesized by a simple hot injection method.
TL;DR: In this paper , the tribological performance was assessed in a ball-on-disk configuration in a unidirectional sliding mode and the results indicated that solution-processed multilayer Ti3C2Tx-MoS2 nanocomposites led to superlubricious states, which has hitherto been unreported for both individual pristine materials, MoS2 or MXene or any combination of the two so far.
Abstract: Toward the goal of achieving superlubricity, or near-zero friction, in industrially relevant material systems, solution-processed multilayer Ti3C2Tx-MoS2 blends are spray-coated onto rough 52100-grade steel surfaces as a solid lubricant. The tribological performance was assessed in a ball-on-disk configuration in a unidirectional sliding mode. The test results indicate that Ti3C2Tx-MoS2 nanocomposites led to superlubricious states, which has hitherto been unreported for both individual pristine materials, MoS2 and Ti3C2Tx, under macroscale sliding conditions, indicating a synergistic mechanism enabling the superlative performance. The processing, structure, and property correlation were studied to understand the underlying phenomena. Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy revealed the formation of an in situ robust tribolayer that was responsible for the performance at high contact pressures (>1.1 GPa) and sliding speeds (0.1 m/s). This report presents the lowest friction obtained by either MoS2 or MXene or any combination of the two so far.
TL;DR: In this article , the structure of as-synthesized samples was characterized by using several techniques, including XRD spectroscopy, Raman spectro-graphs, XPS, SEM, and UV-visible absorption spectrograms, and the results showed that the Bi2O3/MoSe2 sample showed the highest photocatalytic degradation efficiency.
TL;DR: In this article , the electronic structure, charge transfer, and photon scattering of the buckled and planar few-layer two-dimensional (2D) GaN are investigated based on the first-principles calculations.
TL;DR: In this article , a co-precipitation method has been employed to synthesize blossom-like BiVO4 microstructures with incorporation of Co and Na metals, followed by calcination at 350 °C.
Abstract: In this work, we report a synergism of Co/Na in Co@Na–BiVO4 microstructures to boost the photocatalytic performance of bismuth vanadate (BiVO4) catalysts. A co-precipitation method has been employed to synthesize blossom-like BiVO4 microstructures with incorporation of Co and Na metals, followed by calcination at 350 °C. The structure and morphology of the as-prepared photocatalysts are characterized by XRD, Raman, FTIR, SEM, EDX, AFM, UV-vis/DRS and PL techniques. Dye degradation activities are evaluated by UV-vis spectroscopy, in which methylene blue, Congo red and rhodamine B dyes are chosen for comparative study. The activities of bare BiVO4, Co–BiVO4, Na–BiVO4, and Co@Na–BiVO4 are compared. To evaluate the ideal conditions, various factors that affect degradation efficiencies have been investigated. The results of this study show that the Co@Na–BiVO4 photocatalysts exhibit higher activity than bare BiVO4, Co–BiVO4 or Na–BiVO4. The higher efficiencies were attributed to the synergistic role of Co and Na contents. This synergism assists in better charge separation and more electron transportation to the active sites during the photoreaction.
TL;DR: In this article , a solution-based surface-enhanced Raman scattering (SERS) platform utilizing a portable Raman instrument for fast sensitive SERS detection of illegal drugs, such as cocaine, and heroin in human urine without any sample preprocessing.
TL;DR: In this article , the effect of methylammonium lead iodide (MAPbI3) doping with small amounts of rubidium (Rb), lithium (Li), and caesium (Cs) was investigated.
TL;DR: In this paper , a low-cost solution casting method has been used to prepare the polymer blend hybrid nanocomposites at 0.0, 0.1 and 0.3 wt% of Er2O3.
Abstract: Polymer blend hybrid nanocomposites are of great importance for future optoelectronic applications. This paper presents the preparation of new polymer blend hybrid nanocomposites based on PVC/PVP modified with Er2O3 nanoparticles. A low-cost solution casting method has been used to prepare the polymer nanocomposites at 0.0, 0.1, 0.3 and 0.6 wt% of Er2O3. X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, and environmental scanning electron microscopy (ESEM) measurements have all been used to examine the impact of a varying wt% of Er2O3 on the structural and optical characteristics of PVP/PVC polymer blends. The PVC/PVP polymer blend and Er2O3 nanoparticles showed a strong interaction, which was validated by XRD, FTIR, and Raman spectrum investigations. The SEM micrographs showed a remarkable complexation among the components of the polymer nanocomposites. The activation energies for thermal decomposition of PVC/PVP doped with different Er2O3 concentrations were less than that of the pure polymer film. The linear and nonlinear refractive indexes, dispersion energy, optical susceptibility and the energy gap values were found to be Er2O3 concentration-dependent. With an increase in Er2O3 concentration to 0.1 and 0.3 wt%, the dispersion energy and nonlinear refractive index improved, and thereafter decreased when the concentration was further increased to 0.6For the film doped with 0.1 wt% Er2O3, the optical band gap (Eopt) of the composite film enhanced by about 13%. The optical absorption measurements revealed clear improvements with the addition of erbium oxide. Higher refractive index values of PVC/PVP/Er2O3 films qualify the polymer blend as a cladding for electro-optic modulators. Our results indicated that the PVC/PVP/Er2O3 polymer films could be suitable for optoelectronic space applications.
TL;DR: In this paper , the nitrogen doping-induced modulation of Fermi levels in TiO2 nanotubes (TNTs) is investigated for visible-range photocatalytic applications.
Abstract: The work function engineering in metal-oxide nanostructures by judicious doping of impurities is not straightforward as it introduces multiple defects in the system. In this regard, understanding the nitrogen (N) doping-induced modulation of Fermi levels in TiO2 nanotubes (TNTs) is challenging for visible-range photocatalytic applications. Here, 50 keV N ions are implanted in TNTs with a fluence range of 1014–1016 ions/cm2. X-ray diffraction and micro-Raman analyses demonstrate the formation of anatase-TiO2 in pristine TNTs, while the crystalline quality is significantly affected by increasing ion fluence. The evolution of Ti3+ is also established by X-ray photoelectron spectroscopy, whereas ultraviolet photoelectron spectroscopy reveals the reduction in work function due to the formation of oxygen vacancies, in good agreement with X-ray absorption spectroscopy and photoluminescence results. The electron paramagnetic resonance study further identifies the evolution of Ti3+/N-substitutional defect centers. Finally, an enhancement in visible-light-assisted methylene blue and Rhodamine B dye degradation is recorded up to a fluence of 1 × 1015 ions/cm2, and it is correlated with the N-ion implantation-induced formation of electrochemically active states near the conduction band minimum and the valence band maximum. The decrease in degradation efficiency beyond a critical fluence of 1015 ions/cm2 is discussed on the ground of ion-beam-mediated amorphization and the subsequent increase in electron–hole recombination in the defect states.
TL;DR: In this paper , two covalent organic frameworks (COFs) were successfully synthesized for iodine adsorption, and the results of experimental analyses of Fourier transform infrared spectroscopy, X-ray photoelectron spectrographs, and Raman spectrograms showed that their high performance is attributed to the strong interactions between the adsorbed iodine and the uniformly located abundant nitrogen adsorbing sites in the pores of the two COF materials, which are from both pre-introduced acylamides and in situ generated Schiff base imine groups.
Abstract: With the rapid development of the nuclear industry, the effective treatment of radioactive iodine has currently become an urgent but challenging task. Herein, two covalent organic frameworks (COFs), TFBT-1 and TFBT-2, were successfully synthesized for iodine adsorption. Structure analysis revealed that they are both nanoporous materials with one-dimensional channels derived from the packing of the related two-dimensional frameworks. Iodine adsorption experiments demonstrated that both COF materials exhibit effective performance for iodine adsorption, with a maximum amount of upto 3.15 g g–1 for TFBT-1 and 2.60 g g–1 for TFBT-2. The results of experimental analyses of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy clearly revealed that their high performance is attributed to the strong interactions between the adsorbed iodine and the uniformly located abundant nitrogen adsorption sites in the pores of the two COF materials, which are from both pre-introduced acylamides and in situ-generated Schiff base imine groups. The present work revealed that by introducing the nitrogen-rich sites into the frameworks of the COF materials, effective iodine adsorbents can be achieved.
TL;DR: In this paper , a linear dielectric CaTiO3 (CT) additive was introduced into Bi0.5Na 0.6O3-NBNM-0.1CT ceramic to enhance its Eb.