Narrow Results

This study intended to synthesize Nickel-doped Cerium oxide (Ni-CeO₂ NPs) nanoparticles using Pedalium Murex leaf extract. X-ray diffraction (XRD) was used to investigate the structure of the Ni-CeO₂ NPs. The XRD measurements showed that the Ni-CeO₂ NPs crystallized into the face-centered cubic system. The Ni(1%)-CeO₂ and Ni(3%)-CeO₂ NP’s crystallite sizes were between 47nm and 59nm. FTIR and Raman spectral studies were conducted to investigate the sample’s atomic vibrations and chemical bonding. Energy-dispersive X-ray study and field-emission scanning electron microscopy were performed to examine the surface texture and chemical assembly of the Ni-CeO₂ NPs. UV–Vis DRS spectrum study was performed to ascertain the reflectance characteristics and bandgap of Ni-CeO₂ NPs. The Ni(1%)-CeO₂ and Ni(3%)-CeO₂ NPs were found to have bandgaps of 2.73eV and 2.82eV, respectively. Electrochemical impedance spectroscopy and cyclic voltammetry were employed to explore the electrochemical nature of Ni-CeO₂ NPs and their capacitive properties at various scanning rates. Using the agar well-diffusion technique, the antifungal activities of Ni-CeO₂ NPs were assessed. The experimental findings illustrate the utility of Ni-CeO₂ NPs for supercapacitor electrode material and healthcare applications.

This study focused on the corrosion protection performance of plasma polymerized HMDSO thin films in two different corrosive medias, 0.3M NaCl and 0.3M H₂SO₄. The pp-HMDSO thin films were deposited on steel substrates for electrochemical tests using the potentiodynamic polarization technique, they were deposited also on aluminum and silicon substrates to investigate their resistance to corrosion, through the analysis of the degradation of microhardness and morphology, respectively, after immersion of the substrates for one week in the corrosive media. The results showed promising corrosion protection properties of the pp-HMDSO thin films.

The large area, highly uniform copper nanorod arrays with cylindrical morphology in polycarbonate membranes (PC) have been successfully prepared by electrochemical deposition. The copper nanorod arrays have the length of 3 μm, the diameter of 400 nm, approximately, which correspond closely to the pore diameter and thickness of membranes. The copper nanotubes were also obtained by controlling initial voltage and polycarbonate membranes treatment process. The possible growing mechanisms of copper nanostructures in membrane pores were discussed.

In order to enhance the surface properties of P110 oil casing tube steel and increase its usage during operation, chromium coating was fabricated by pack cementation. Scanning electron microscope, energy dispersive spectrometry and X-ray diffraction were used to investigate the surface morphology, cross-sectional microstructure, element distribution and phase constitutions of the coating. Comparative examinations on corrosion resistance between chromium coating and 13Cr stainless steel in CO₂-saturated simulated oilfield brine were carried out via electrochemical measurements. The results showed that the obtained coating was uniform and compact, mainly consisted of Cr_xC_y and doped with minor Cr₂N. Chromizing treatment made it possible to create on the working surface of P110 steel with enhanced corrosion resistance, and the chromium coating indicated lower pitting corrosion sensitivity than that of 13Cr stainless steel.

In order to evaluate the left life of the aircraft tank in the storage stage and enhance the reliability of aircraft, the electrochemical corrosion characteristic of 2A14 aluminum alloy has been investigated by the polarization curve method, electrochemical impedance spectroscopy methods and soaking corrosion test in this paper. The corrosion equivalent relationship of 2A14 aluminum alloy at different conditions was established. Moreover, the corrosion mechanism and law of 2A14 aluminum alloy in the solution of N2O4-HNO3 were obtained. It is shown that the nitric acid with the volume fraction of 30% corrodes 2A14 aluminum alloy had the fastest speed. The corrosion intensity of the specimen increases with the increase of the environment temperature. In the corrosion program, the corrosion is begun with the pit with very small size. As the time passes by, the pits expand and the adjacent pits combines together to be a larger pit. Finally, the thickness of the specimen decreases uniformly as the corrosion product peels off from the surface of the specimen. Therefore, the corrosion evaluation of aluminum alloy structure can be performed by weighting or measuring the thickness in application.

In this paper, we have successfully synthesized ZnO nanoparticles (Nps) via solution combustion method using sugarcane juice as the novel fuel. The structure and morphology of the synthesized ZnO Nps have been analyzed using various analytical tools. The synthesized ZnO Nps exhibit excellent photocatalytic activity for the degradation of methylene blue dye, indicating that the ZnO Nps are potential photocatalytic semiconductor materials. The synthesized ZnO Nps also show good electrochemical sensing of dopamine. ZnO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Eschesichia coli and Staphylococcus aureus using agar well diffusion method. Furthermore, the ZnO Nps show good antioxidant activity by potentially scavenging 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The above studies clearly demonstrate versatile applications of ZnO synthesized by simple eco-friendly route.

A family of meta octa-substituted 5,10,15,20-tetraphenylporphyrin derivatives and their metal (Cu(II) and Zn(II)) complexes were examined by electrochemical studies. These functionalized MTPPs exhibited a dramatic anodic shift (>200 mV) in their first ring redox potentials relative to the para-phenyl substituted-MTPP(X) complexes and follow a fairly linear relationship with the Hammett parameter of the substituents. The extent of Lewis acidity of the core Zn(II) center in these porphyrins was probed by axial ligation of bases of varying pK_a values. The increase in K_eq values of the electron deficient Zn(II) porphyrins are as high as an order of magnitude and increase with anodic shift of the electrochemical redox potentials of the porphyrin. A crystal structure of the Zn(II) octa(carboxyethylester phenyl)porphyrin shows six-coordination geometry with the coordination through peripheral ester groups to form a supramolecular two-dimensional layer structure while the ZnT(3',5'-DMP)P complex exhibited a five-coordinate structure.

A series of $\beta$-pyrrole functionalized push-pull BODIPYs BDP 1-06 were designed and synthesized via Palladium-catalyzed Suzuki cross-coupling reaction and by increasing the oxidation state of the sulfur atom in the thiazine ring. The effect of various donor entities on the photophysical, electrochemical, thermal, and computational studies of the BODIPY was investigated. The absorption spectra of the push-pull BODIPY BDP 2 show a red shift compared to the rest of the BDPs, due to strong donor-acceptor interaction. The phenothiazine-5,5-dioxide functionalized BODIPY BDP 6 exhibit a blue shift in the UV-vis region compared to the phenothiazine substituted BODIPY BDP 5 due to the weak donor ability of the phenothiazine-5,5-dioxide unit. The electrochemical studies were performed for the push-pull BODIPYs BDP 1–6 to analyze the effect of different donor groups on the redox properties of the BODIPY. The thermogravimetric analysis of the BODIPYs BDP 1–6 shows that BDP 2 exhibits excellent thermal stability compared to BDP1, 3, 4, 5, and 6. The theoretical studies reveal that the phenothiazine-5,5-dioxide substituted BODIPY BDP 6 exhibits a large HOMO–LUMO gap compared to phenothiazine functionalized BODIPY BDP 5 due to the low donor ability of the phenothiazine-5,5-dioxide unit. The theoretical calculations were consistent with the experimental observations.

This study delineates the synthesis and comprehensive characterization of metal complexes of meso-tetrakis(pentafluorophenyl)porphyrin (H₂TPF${}_{20}$P, 1) with first-row transition metal ions (M = Mn(III) 2, Fe(III) 3, Co(II) 4, Ni(II) 5, Cu(II) 6, and Zn(II) 7) to elucidate their structural, electronic spectral, and electrochemical redox properties. Co, Ni, Cu and Zn Complexes exhibit planar structure ($\mathrm{\Delta }$24 = 0.003-0.021 Å and $\mathrm{\Delta }$C${}_{\beta }$ = 0.004−0.041 Å) which is also confirmed by the single crystal data of complex ZnTPF${}_{20}$P, 7 shows the planar geometry, while Fe and Mn complexes show the slightly nonplanar structure ($\mathrm{\Delta }$24 = 0.101–0.143 Å and $\mathrm{\Delta }$C${}_{\beta }$ = 0.080–0.112 Å), which are distorted due to their occupied axial sites by −Cl ligand as revealed by density functional theory (DFT) calculations. Furthermore, electronic spectroscopy revealed a gradual bathochromic shift following the order of NiTPF${}_{20}$P < CoTPF${}_{20}$P < CuTPF${}_{20}$PCl < H₂TPF${}_{20}$P = FeTPF${}_{20}$PCl < ZnTPF${}_{20}$P < MnTPF${}_{20}$PCl by appending different metal ions in the porphyrin core. MnTPF${}_{20}$PCl exhibited the most significant bathochromic shift ($\mathrm{\Delta }{\lambda }_{\text{max}}$ = 63 nm) in the Soret band compared to H₂TPF${}_{20}$P. Also, MnTPF${}_{20}$PCl and FeTPF${}_{20}$PCl show a unique pattern of split Soret band at around 364 and 345 nm due to the interaction between the metal $d$-orbitals and the surrounding ligands. The electrochemical redox potentials of the filled 3d orbital of Zn endow ZnTPF${}_{20}$P (ring centered) with the lowest oxidation potential.

Recent development and challenges in DNA biosensing technology for the detection of DNA hybridization are reviewed with respect to their abilities to achieve lower detection limit and higher selectivity. Researchers exploit a range of different chemistries for the development of DNA hybridization biosensors, however all the designs take advantage of heterogenous hybridization between the surface-bound DNA (the probe) and the DNA sample (target) in the solution. The detection protocols include using optical, microgravimetry, and electrochemical-based device to transduce DNA hybridization by observing changes in light, mass/frequency, and current/charge, respectively, upon exposure to the sample. The pros and cons of these biosensor designs are discussed with illustrative examples.

Ag/Co nanoparticles (NPs) were prepared by a two-step method. First, Ag NPs were synthesized by "Controlled Current Coulometry" (CCC) electrochemical method using a Pt rotating electrode. Then, Ag/Co core-shell NPs were prepared through the reduction method using Ag NPs as a core. Both steps were accomplished at room temperature. Techniques such as patterned X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed for the characterization of Ag/Co NPs. Optical properties of synthesized NPs were also investigated by UV-Vis spectroscopy. The absorption peak of Ag NPs was observed at ~400 nm wavelength and the peaks that were detected at 425 nm and 415 nm wavelengths reveal the formation of Ag/Co NPs. The core-shell structure of Ag/Co NPs was confirmed by thermal and electrochemical techniques. We also applied "Mie" theory to calculate the absorption cross-section band of synthesized Ag/Co NPs. Comparison between the results of optical properties and also those obtained from "Mie" theory showed good agreements.

A facile green approach has been developed to control the growth regime in the aqueous synthesis of Cd_xZn_1-xTe semiconductor quantum dots (QDs) based on the electrochemistry method. The Low growth temperature and slow injection of Te precursor are used to prolong the diffusion controlled stage and thus suppress Ostwald ripening during the nanocrystal growth. The experimental results showed that a low concentration of Te precursor will definitely influence the growth procedure. The UV–visible absorption spectra, as well as transmission electron microscopy (TEM) shows the QDs a good monodispersity at any interval of the reaction procedure. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs have high crystallinity and cubic structure. The size and composition-dependent fluorescent emission wavelength of the resultant Cd_xZn_1-xTe alloyed QDs can be tuned from 460 to 610 nm, and their photoluminescent quantum yield can reach up to 70%. Especially in the wavelength range of 510–578 nm, the overall PL QYs of the as-prepared Cd_xZn_1-xTe QDs were above 50%. The current work suggests that electrochemical method is an attractive approach to the synthesis of high-quality II-VI ternary alloyed semiconductor QDs at large-scale with a prominent cost advantage.

Photocatalytic activity can be improved through modified morphology and structure. Sodium tantalate (NaTaO₃) as a semiconductor photocatalyst is extensively used for photocatalytic water splitting. A novel electrochemical route was developed for preparing NaTaO₃ spheres. The method can easily and fast synthesize high pure phase NaTaO₃ spheres at room temperature. The NaTaO₃ sphere structure consists of a crystalline core and an amorphous shell. After a thermal treatment, the NaTaO₃ spheres show an enhanced photoelectrochemical water splitting ability.

We report an efficient and green approach for mass production of few layered graphene nanosheets (FLGNSs) by intercalation and exfoliation of pyrolytic graphite sheet in a simple protic, H₂SO₄ electrolyte. The as-prepared FLGNSs at the optimum intercalate concentration of 0.5 M H₂SO₄ is able to produce large domain of lateral dimension of 11–26 μm consisting of 4–6 stacked graphene layers, as confirmed by field emission scanning electron microscopy and atomic force microscopy, respectively. Surface oxygenation and a characteristic absorbance peak at 228 nm are well observed for electrochemical exfoliated FLGNSs from Fourier transform infrared spectroscopy and UV–Vis spectra respectively. (002) planes of the obtained graphene sheets have been confirmed from X-ray diffraction pattern. The characteristic Raman bands have been observed at 1354 cm^-1 and 1590 cm^-1 in the exfoliated FLGNSs.

The sandwich-type immunoassays have been developed by using electrochemical and surface-enhanced Raman scattering (SERS) techniques for the detection of carcinoembryonic antigen (CEA). Nile blue as a kind of Raman dye has been decorated on nanospheres with polydopamine resin (PDR) via $\pi$-stacking interaction. The Nile blue displays the strong SERS signals as well as a characteristic electrochemical reduction peak at $-$0.33V (versus Ag/AgCl). The implementation of the PDR nanospheres mixing with Au nanoparticles (AuNPs/PDR) exhibits a better electrical conductivity and large SERS enhancement. The immunoassays based on Nile blue-labeled AuNPs/PDR nanospheres have been fabricated by using electrochemical and SERS techniques for the detection of CEA. The proposed immunoassay shows higher sensitivity, high selectivity, lower detection limit and long-term stability. The performances of the electrochemical immunoassay are better than that of SERS immunoassay. For the electrochemical immunoassay, the linear range occurs from 1pg/mL to 100ng/mL ($R=0.995$) with a detection limit of 0.68pg/mL and signal-to-noise ratio of 3 in the detection of CEA. The data for the analysis of human serum samples by using the electrochemical method are acceptably consistent with those obtained from the enzyme-linked immunosorbent assay (ELISA). The proposed immunoassay exhibits a promising potential for application in clinical diagnosis.

Electrochemical energy storage and conversion have been in a significant position for meeting the increasing demand for the development of the society. The design and preparation of high-performance functional semiconductor materials have played a critical role in the development of electrochemical energy storage and conversion. In this context, the nanostructures in functional semiconductor materials provide an alternative route by virtue of their unique and promising nanoscale. Controlling the geometrical parameters of nanostructures and thus forming expected nanomaterials is very important to the investigation and applications of functional semiconductor materials. In this review, we summarized the preparation and applications of the nanostructures for electrochemical energy storage and conversion. It demonstrates simple and controllable design methods for functional materials with ideal nanostructures.

To improve the electrochemical performance of the supercapacitor, three electrode nanocomposites, NiO, NiS and NiCo₂S₄, have been obtained by simple hydrothermal process and high temperature pyrolysis, and further, the impact of electrolytes of different concentrations on electrochemical performance of supercapacitor has been researched. During the research processing, synergistic effect of Ni, Co and S is considered to enhance the electrical conductivity, and promote electron transfer, ion diffusion and structural stability. The experiment results show that bimetallic sulfides display high electrical conductivity, shorter ion diffusion channels, and faster electron and ion transport rate with the feature of topping electrochemical properties of specific capacity, excellent cycling stability and high rate capability, and besides show that it can improve the electrochemical performance of the material by increasing the concentration of electrolyte. The transition-metal sulfides provide a new promising pathway for the expansion of high-performance electrode materials for supercapacitors.

The sulfuric acid-doping polyaniline (H-PANI-HSO₄) are applied to conduct the electrochemical measurement and simulation calculation to investigate the capacitance, electronic structure and energy band properties. The H-PANI-HSO₄ growing on graphite carbon paper (H-PANI-HSO₄/GCP) is applied as an electroactive electrode to investigate electrochemical properties. The Faradaic capacitance of H-PANI-HSO₄/GCP electrode is ascribed to the reversible redox reaction of bisulfate anion doping/dedoping protonated PANI (H-PANI). Cyclic voltammetry measurement at a scan rate of 5mVs${}^{-1}$ determines an equivalent mean response current of 0.64Ag${}^{-1}$ and a capacitance of 128.35Fg${}^{-1}$. Galvanostatic charge–discharge measurement determines specific capacitance from 129.06 to 116.88Fg${}^{-1}$ at current densities from 0.5 to 2.5Ag${}^{-1}$. Cyclic voltammetry-based capacitance at equivalent current density of 0.64Ag${}^{-1}$ is in accordance with galvanostatic charge–discharge-based capacitance at the current density of 0.57Ag${}^{-1}$. Electrochemical impedance spectrum measurements indicate that H-PANI-HSO₄/GCP exhibits lower charge-transfer resistance, much lower Warburg resistance, higher quasicapacitance than H-PANI-HSO₄ to approaching ideal capacitor. Density functional theory calculations indicate that H-PANI-HSO₄ has a higher density of states (10.6 electron/eV) and lower bandgap energy (0.481eV) than H-PANI (5.24 electron/eV, 1.449eV), indicating its enhanced electronic conductivity. The electronic bandgap energy is accordingly decreased from 0.263eV for H-PANI-HSO₄/GCP to 0 for H-PANI-HSO₄/GCP. Electrochemical measurement and simulation calculation investigation proves that H-PANI-HSO₄/GCP electrode with anion-doped and protonated state exhibits higher electronic conductivity and capacitance performance to act as superior electroactive material.

Advanced oxidation technology based on PeroxyMonoSulfate (PMS) has become a research hotspot in the field of water treatment. To improve the activation efficiency of PMS, electrochemically assisted spinel type catalyst CoFe₂O₄ was used to activate PMS and achieve effective degradation of acetaminophen. The influence of single factor on degradation was explored to determine the best degradation process parameters of E/CoFe₂O₄/PMS system. Results show that under the optimum reaction conditions (DC voltage is 6V, the initial mass concentration of acetaminophen is 10mgL${}^{-1}$, the dosage of CoFe₂O₄ is 0.3gL${}^{-1}$, and the mass concentration of PMS is 1.5gL${}^{-1}$), the degradation rate of acetaminophen reaches up to 95% within 20min. CoFe₂O₄ catalyst showed a good stability, with only a 12% decrease in acetaminophen degradation after three cycles. Radical quenching tests show that $\cdot \mathrm{\text{OH}}$ and ${\mathrm{\text{SO}}}_4^{-}\cdot$ played predominant roles in the advanced oxidation process. This work provides a new strategy for more efficiency in PMS activation.

We demonstrate here a facile and effective strategy to prepare reduced graphene oxide-platinum nanoparticle (RGO-PtNP) nanohybrids by the mediation of graphite-specific peptide (GSP). For the first time, we found that GSP can be used to modify RGO non-covalently in one way, and in another way promote the formation of PtNPs on RGO as a biomolecular bridge. The created RGO-PtNP nanohybrids show enhanced electrocatalytic activity toward H₂O₂ and can be utilized to fabricate non-enzymatic electrochemical H₂O₂ sensor.