Facile Chemical Process Research Articles

Preparation of Asymmetric Al2O3-SiO2 Janus Nanoparticles in Aqueous Phase and Its Interfacial Property.

In this study, asymmetric Al2O3-SiO2 Janus nanoparticles with a dumbbell-like structure were synthesized by a facile chemical process in the aqueous phase. Prior to synthesis, Al2O3 nanoparticles in hydrosol were amino-modified using 3-aminopropyl triethoxysilane (KH550) and then carboxyl acid-functionalized using a ring-opening reaction of the amine functions with succinic anhydride, imparting unique anionic properties to the Al2O3 end. SiO2 nanoparticles were rendered hydrophobic through modification with hexamethyldisilazane (HMDS) and further functionalized with 3-chloropropyl triethoxysilane (KH230). The two nanoparticle hydrosols were then mixed, and the asymmetric Al2O3-SiO2 Janus nanoparticles were synthesized via the reaction between the -NH2 and -CH2Cl groups. The prepared Janus nanoparticles were primarily characterized by dynamic light scattering (DLS), Zeta potential (ZP), and transmission electron microscopy (TEM). The results indicated that about 90% of the modified Al2O3 and SiO2 nanoparticles were covalently coupled in a one-to-one manner to form the dominant dumbbell-like structure. These Janus nanoparticles exhibit amphiphilic properties, making them highly promising surfactants for emulsifying oil-water mixtures.

The Influence of Silica Dioxide in the Electrocatalytic Performances of rGO/Fe<sub>3</sub>O<sub>4</sub> as Oxygen Reduction Electrocatalyst

In this study, synthesis of reduced graphene oxide-iron oxide-silica dioxide (rGO/Fe3O4/SiO2) was done through a facile chemical process. Physical characterization was carried out as such Fourier transform infrared spectroscopy (FTIR) which confirmed the presence of silica peak in the spectrum of rGO/Fe3O4/SiO2, while RAMAN displayed the vibrational bands of carbon materials studied. Results of SEM-EDX and TEM confirmed the unification of SiO2 on rGO/Fe3O4 nanocomposite with difference in morphologic structure. X-ray diffraction (XRD) analysis exhibited that addition of SiO2 increased the crystalline size of the nanocomposite. Nitrogen adsorption isotherm analysis describes the nanocomposites fall in the mesopore region. The nanocomposite was then drop-casted on the surface of glassy carbon electrode (GCE) for fabrication of the electrode which denoted as rGO/Fe3O4/SiO2/GCE. Electrochemical characterization of modified electrode was studied using electron impedance spectroscopy (EIS), which showed the minimal resistance charge transfer. Oxygen reduction reaction analysis shows that electrocatalytic reduction of oxygen was excellent with four-electron transfer when calculated using Randles-Sevcik equation. All the analysis was compared to the nanocomposites without the addition of silica oxide (rGO/Fe3O4). This work proves that addition of nanoparticle in a compound as a matrix improves the oxygen reduction potential of rGO/Fe3O4/SiO2/GCE composite.

ZnS/ZnSe heterojunction photocatalyst for augmented hydrogen production: Experimental and theoretical insights

A facile chemical process for the synthesis of ZnS/ZnSe composites and theoretical and experimental insights into their sunlight-driven photocatalytic H2 production via water-splitting reactions are demonstrated. ZnSe systems are varied by synthesizing at various temperatures such as 80, 150, and 180 °C for 12 h via hydrothermal process to tune their crystalline properties while maintaining ZnS as the host material, which is the main driving force to achieve increased photocatalytic H2 production efficiency in this study. The prepared composite photocatalyst is found to have cubic ZnS and wurtzite ZnSe phases with good overall crystalline properties. The morphological investigation revealed that the composite consists of ZnS with a spherical structure coupled with irregular-structured ZnSe particles. The optimized ZnS/ZnSe (ZnSe prepared at 150 °C) photocatalyst showed the highest H2 generation of around 84.8 mmol h−1 g−1cat, with a UTH (i.e., UV–visible-to-H2) conversion efficiency and turnover frequency of 20.4% and 0.097 Atom−1 s−1, respectively. This observed photocatalytic efficiency is presumed to be the formation of type-I heterojunction channelizing the effective transfer of hot photocarriers from ZnS to ZnSe for the rapid production of protons (H+) and their subsequent reduction to H2 molecules. The achieved highest efficiency of the composite is around 56.4 and 4.2 folds higher than the pristine ZnSe and ZnS, respectively. In addition, the recycle experiments of the optimized catalyst showed consistent H2 production for upto 5 cycles. Further, the developed composite systems are investigated via density functional theory and validated through various physio and electrochemical analyses to understand their structure-property relationships and photocatalytic mechanisms toward water splitting for H2 production.

Ultra-fast photocatalytic degradation and seed germination of band gap tunable nickel doping ceria nanoparticles

Doping transition metal ions into cerium oxide (CeO2) results in interesting modifications to the material, including an increase in surface area, a high isoelectric point, biocompatibility, greater ionic conductivity, and catalytic activity. Herein, various concentrations (1–5%, 10% and 20%) of nickel (Ni) doped CeO2 nanoparticle have been made by a facile chemical process. Using a variety of cutting-edge analytical techniques, the structural, optical, and photocatalytic properties of undoped and varied concentrations (1–5%, 10%, and 20%) of Ni doped CeO2 nanoparticles have been investigated. Pure cubic fluorite structure with average crystallite sizes in the region of 12–15 nm was determined by X-ray diffraction (XRD) investigation. Transmission electron microscopy (TEM), which revealed highly homogeneous hexagonal shape of the particles with average size of 15 nm, was also used to determine microstructural information. According to the optical absorption, the band gaps of Ni doped and undoped CeO2 nanoparticles were found to be 2.96 eV and 1.95 eV, respectively. When exposed to sunlight, the narrow band gap Ni doped CeO2 nanoparticles worked as an active visible light catalyst to remove the dyes Rose Bengal (RB) and Direct Yellow (DY). The best photodegradation efficiencies for RB and DY dyes were found about 93% and 97%, respectively, using the 5% Ni-doped CeO2 catalyst. The apparent rate constant values of 0.039 for RB and 0.040 min−1 were attained for DY. As well, the treated, untreated dye solution and control solutions were utilized to assess the toxicity of commercially accessible Vigna Radiata seeds. In this study exhibits percentages of length and germination increased by 30–35% when compared to dye pollutant solution. The Ni doped CeO2 can provide a substantial alternative for current industrial waste management because of its quick photocatalytic activity and remarkable seed germination results.

Strain-Insensitive Stretchable Fiber Conductors Based on Highly Conductive Buckled Shells for Wearable Electronics.

Based on their high applicability to wearable electronics, fiber-based stretchable electronics have been developed via different strategies. However, the electrical conductivity of a fiber electrode is severely degraded, following deformation upon stretching. Despite the introduction of conductive buckled structures to resolve this issue, there still exist limitations regarding the simultaneous realizations of high conductivity and stretchability. Here, we exploit the dense distribution of the Ag nanoparticle (AgNP) network in polyurethane (PU) to fabricate a strain-insensitive stretchable fiber conductor comprising highly conductive buckled shells via a facile chemical process. These buckled AgNPs/PU fibers exhibit stable and reliable electrical responses across a wide range (tensile strain = ∼200%), in addition to their high electrical conductivity (26,128 S/m) and quality factor (Q = 2.29). Particularly, the negligible electrical hysteresis and excellent durability (>10,000 stretching-releasing cycles) of the fibers demonstrate their high applicability to wearable electronics. Furthermore, we develop buckled fiber-based pH sensors exhibiting stable, repeatable, and highly distinguishable responses (changing pH is from 4 to 8, response time is 5-6 s) even under 100% tensile strain. The buckled AgNPs/PU fibers represent a facile strategy for maintaining the stable electrical performances of fiber electrodes across the strain range of human motion for wearable applications.

Capacitance performance of Ti3C2Tx MXene nanosheets on alkaline and neutral electrolytes

The high electrical conductivity, good hydrophilicity, and various surface terminal configurations of MXenes have exposed extensive attention in the field of energy storage. Ti3C2Tx MXene was synthesised via a facile chemical process. A study of Ti3C2Tx MXene's structure, composition, and morphology was carried out using X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and Field emission scanning electron microscopy (FESEM). A detailed study of the influence of aqueous electrolytes on the charge storage performance of Ti3C2Tx MXene was conducted by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), cyclic stability (CS), and electrochemical impedance spectroscopy (EIS). In addition, it is proposed that Ti3C2Tx MXene's surface terminations affect its capacitance behaviour in aqueous electrolytes. Ti3C2Tx MXene in 3 M (KOH) alkaline electrolyte has good electrochemical performance, with a specific capacitance (Cs) of up to 92 F/g at 2A/g, making it a potential material for supercapacitors.

Facile and efficient chemical synthesis of gluco-oligosaccharides (GlcOS) with diverse glycosidic linkages as potential prebiotics to promote the growth of probiotic bacteria

Glucose-based short-chain oligosaccharides (gluco-oligosaccharides, GlcOS) have been established as functional food ingredients with health-promoting properties. Currently, GlcOS (e.g., isomalto-oligosaccharides, IMOs) are commercially produced via enzymatic processes, which face the challenges of low yield and high cost. Therefore, developing efficient technologies for large-scale production of prebiotic GlcOS is highly desirable. Herein, a facile chemical process was developed to synthesize GlcOS as potential prebiotics via enhanced dehydration condensation of glucose in concentrated sulfuric acid (60–92 %). The maximum GlcOS yield of 83 % was achieved under the optimal condition of 50 % initial glucose loading, 76 % H2SO4, 70 °C, and 20 min. Structural analysis revealed that the synthesized GlcOS are mainly short-chain oligomers with a degree of polymerization (DP) between 2 and 4 (46 % DP 2, 22 % DP 3, 12 % DP 4) and a small percentage of larger oligosaccharides (DP 5–9), which are linked by predominantly α- and β-(1→6) linkages along with (1→4), (1→ 3), (1→2), and (1↔1) linkages. In vitro fermentation experiments by probiotic Bifidobacterium bifidum ATCC 29521, Bifidobacterium animalis subsp. lactis DSM 10140, and Limosilactobacillus reuteri ATCC 6475 indicated that the GlcOS can be utilized as a carbon source for bacterial growth, and their promotion effect was overall comparable to three commercial prebiotic IMOs. GlcOS were also successfully synthesized from maltose and cellobiose with similar yield and structures to those from glucose, implying the possibility of synthesizing the prebiotic GlcOS directly from inexpensive starch and cellulose.

Reactive boride as a multifunctional interface stabilizer for garnet-type solid electrolyte in all-solid-state lithium batteries.

All-solid-state batteries are one of the most important game changers in electrochemical energy storage since they are free from the risk of leakage of hazardous flammable liquid solvents. Among the various types of solid-state electrolytes, Li7-xLa3Zr2-xTaxO12 garnets possess many desirable advantages to be considered a suitable candidate for lithium-ion batteries. However, their practical application has been hindered by premature short-circuits due to lithium dendrite growth, nonnegligible electronic conductivity and interfacial air sensitivity issues. Herein, we propose a multifunctional layer strategy to simultaneously address both the interface and electronic conductivity issues. With the help of a facile chemical process based on reactive cobalt boride, electron leakage was effectively blocked and the electrochemical performance/stability could be well maintained over extended cycles. The cobalt boride-coating layer also possessed an impressive Li metal wetting ability while sustaining a low interfacial resistance. A full cell paired with a commercialized cathode showed satisfactory performance with low overpotentials and a high specific capacity over 150 mA h g-1. Moreover, first-principle calculations further revealed the status of the rearrangement of the electron cloud behind the charge-density difference, and the nature of the low diffusion energy barrier of the reactive cobalt boride protective layer. Our strategy highlights the necessity of designing proper multifunctional layers in the garnet-type solid-state lithium-ion battery system.

Phototherapy Using a Fluoroquinolone Antibiotic Drug to Suppress Tumor Migration and Proliferation and to Enhance Apoptosis.

In this work, a fluoroquinolone antibiotic drug (sparfloxacin (SP)) was selected as a chemotherapy drug and photosensitizer for combined therapy. A facile chemical process was developed to incorporate SP and upconversion nanoparticles (UCNPs) into the thermally sensitive amphiphilic polymer polyethylene glycol-poly(2-hexoxy-2-oxo-1,3,2-dioxaphospholane). In vitro and in vivo experiments showed that 60% of the SP molecules can be released from the micelles of thermal-sensitive polymers using a 1 W cm-2 980 nm laser, and this successfully inhibits cell migration and metastasis by inhibiting type II topoisomerases in nuclei. Additionally, intracellular metal ions were chelated by SP to induce cancer cell apoptosis by decreasing the activity of superoxide dismutase and catalase. In particular, the fluoroquinolone molecules produced singlet oxygen (1O2) to kill cancer cells, and this was triggered by UCNPs when irradiation was performed with a 980 nm laser. Overall, SP retained a weak chemotherapeutic effect, achieved enhanced photosensitizer-like effects, and was able to repurpose old drugs to elevate the therapeutic efficacy against cancer, increase the specificity for suppressing tumor migration and proliferation, and enhance apoptosis.

Z-scheme g-C3N4/Bi6Fe1.5Co0.5Ti3O18 heterojunctions with enhanced visible-light photocatalytic activity towards organics degradation

Construction of heterostructure is an efficient approach to improve the photocatalytic performance of catalysts. Herein, the Bi6Fe1.5Co0.5Ti3O18 (BFCTO) nanoplates are successfully loaded on g-C3N4 nanosheets by a facile chemical process for the first time. The photocatalytic activity of all g-C3N4/BFCTO catalysts are measured by the degradation of Rhodamine B (RhB) under visible-light irradiation. The results display that g-C3N4/BFCTO heterojunctions exhibit greatly improved photocatalytic activity compared with corresponding bare g-C3N4 and BFCTO catalysts. Based on the experimental results of photocurrent responses, EIS and ESR, it is clearly demonstrated that the improved activity is attributed to the formation of Z-scheme photocatalyst. The g-C3N4/BFCTO-2 heterojunction showed the optimal photocatalytic activity with the photodegradation efficiency of 84.9% within 20 min. We hope that the work can provide a new insight for exploring Bin+1Fen−3Ti3O3n+3-based Z-scheme heterojunction for pollutant degradation and environment restoration.

A facile chemical process to form an ultrathin hydroxyapatite layer with a customizable silver-releasing function on a titanium implant.

Silver-containing hydroxyapatite (Ag/HAp) layer on a bioinert material provides both bioactive and antibacterial properties; however, the Ag release duration needs to be customized to a patient's age and metabolism for minimizing the toxic effects. Herein, we present a facile chemical process to produce an ultrathin Ag/HAp layer on a Ti implant with a customized Ag-releasing profile. The process involves the following steps: preparation of a slurry-type reagent by mixing calcium phosphate powder with an aqueous AgNO3 solution, burying a Ti substrate in the slurry, and heating the slurry in air. An HAp layer, approximately 50 nm thick, with Ag particle deposits was obtained using this process. The Ag-particle content can be varied by adjusting the concentration of AgNO3 solution used for slurry preparation, resulting in different Ag-release profiles in a physiological solution. For instance, Ag release was retained for up to 30 days when 100 mM AgNO3 was used, whereas the release lasted 15 days when 10 mM AgNO3 was used. The duration of the antibacterial activity varied accordingly, but Ag-release-derived cytotoxicity was not observed irrespective of the AgNO3 concentration. In addition, differentiation of osteoblast-like cells was facilitated owing to the formation of the HAp layer. Thus, the chemical process presented in this study allows the production-at a clinical site-of an Ag/HAp layer customized to the patient's needs.

Facile preparation of worm-like mesoporous tin oxide films with super-hydrophilic surface

Herein mesoporous tin oxide films were synthesized via a facile chemical process. The effect of calcination temperature and drying conditions on various characteristics of prepared thin films were studied systematically. The results demonstrated that the mesoporous thin films were well organized with uniform surfaces and thermally stable up to 500 °C. The sample aged under low relative humidity (RH = 34%) and calcined at 400 ℃ showed 86.1 m2/g specific surface area. Highly uniform wormlike mesochannels with highest surface area were obtained for the mesoporous SnO2 film which was aged under high relative humidity (RH = 80%) and calcined at 400 ℃ (MTO400-80 sample). A super-hydrophilic surface with a very low contact angle of <5° was observed for the MTO400-80 sample. The excellent wettability along with high surface area and low sheet resistance, resulted in highest photocatalytic activity for degradation of dye molecules with reaction constant of 5.2 × 10−4 min−1 for MTO400-80 sample.

An impact of La doping content on key physical properties of PbS spherical nanoparticles facilely synthesized via low temperature chemical route

Herein, we are reporting a facile chemical process to attain high-grade PbS spherical nanoparticles with diverse La doping contents at low temperature and named it as La@PbS SNPs. All the prepared La@PbS SNPs samples are of single-cubic phase with good crystalline nature confirmed from XRD and Rietveld refinement. Along with lattice constants several other structure-related parameters like size, dislocations, strain, stacking fault, density and specific surface area were calculated. EDX and SEM-e-mapping analyses confirm the presence of La in PbS with homogeneous distribution throughout the samples. For morphological investigation FESEM was employed, which approved the synthesis of SNPs of low dimensions at all La contents. FT-Raman analysis shows characteristics vibrational modes related to cubic-PbS and that is in good accordance with XRD outcomes. Energy gap values were determined through Kubelka–Munk procedure and noticed to lie between 1.01 to 1.103 eV ( $$ \Delta E = 0.093 \;{\text{eV}}) $$ , this shows a very minute shift in energy gap with La doping in PbS. Dielectric constant ( $$ \varepsilon ' $$ ), loss tangent, dielectric loss and impedance values were assessed and stable values of $$ \varepsilon ' $$ were noticed in 20–50 range and 5.0 wt % La@PbS SNPs possesses highest value. The ac electrical conductivity analysis revealed enhancement with La content in PbS. The correlated barrier hoping mechanism was involved in the prepared La@PbS SNPs. Furthermore, the DC electrical properties were studied and discussed the impact of La content.

Hydrothermal preparation of Zn-doped In2O3 nanostructure and its microstructural, optical, magnetic, photocatalytic and dielectric behaviour

In this communication, indium oxide (In2O3) and Zn-doped In2O3 nanoparticles with different zinc percentage (0–5%) have been prepared by a facile chemical process. A variety of analytical tools such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV–Visible, photoluminescence spectroscopy, photocatalytic measurements and impedance spectroscopy were employed to assess the characteristics of prepared nanoparticles (NPs). From XRD analysis it is observed that all samples exhibit pure cubic phase with highly crystalline nature. XPS spectra revealed the composition and chemical state of Zn-doped In2O3 NPs. The estimated optical band gap was found to decrease with increase of Zn concentration. Magnetic hysteresis exhibited that pure and Zn-doped In2O3 NPs possess ferromagnetic behavior at room temperature. Dielectric constant (ε ’) as well as dielectric loss (ε ’’) decreases exponentially in lower frequency range, but remains almost constant in higher frequency range. Moreover, Zn(5%)-doped In2O3 nanoparticles showed much higher photocatalytic activity as compared with pure In2O3 nanoparticles towards degradation of hazardous methylene blue dye. The results of present study demonstrated that synthesized nanoparticles may be employed efficiently as environmentally convenient photocatalyst for industrial effluent treatment.

Tuned magnetic properties of Co-doped ZnO/B-doped graphene PN junction

Co-doped ZnO(Zn1−xCoxO)/B-doped graphene(BG) PN junction with quasi-core-shell nanostructure is designed and fabricated by a facile chemical process. The interplay between the Zn1−xCoxO core and the BG shell is discussed. X-ray Photoelectron Spectroscopy (XPS) and photoluminescence (PL) spectra confirm that B and Co2+ ions are doped successfully. The C1s XPS spectra suggest the formation of the Zn(Co)OCO bonds, which can efficiently transfer the holes from BG to Zn1−xCoxO. X-ray diffraction (XRD) displays that Co doping hardly changes the wurtzite structure of ZnO. It can be clearly seen that edge of the BG covers Zn1−xCoxO to form the quasi-core-shell structure by High-resolution transmission electron microscopy (HRTEM). The position of the G band in Raman spectrum indicates that BG is P-type. The interaction between the Zn1−xCoxO and BG can be found by the red-shifts of E2H band of Zn1−xCoxO and broader 2D of BG as well. Magnetization measurement demonstrates that the increasing of the ferromagnetic phases in Zn1−xCoxO/BG nanoparticles with the increasing temperature. The observed ferromagnetic phases can be due to the exchange of the electron/hole at interface in the Zn1−xCoxO/BG PN junction.

Synthesis and microwave absorbing properties of γ-Fe2O3–SiO2–poly (3,4-ethylenedioxythiophene) core–shell–shell nanocomposites

The three-layer core–shell–shell γ-Fe2O3–SiO2–poly (3,4-ethylenedioxythiophene) (PEDOT) nanocomposite has been successfully synthesized by a facile chemical process followed by a detailed investigation of morphology, composition, electromagnetic, and microwave absorption properties. The electrical conductivity of γ-Fe2O3–SiO2–PEDOT nanocomposites was as high as 3.34 S cm−1, and the saturation magnetization was in the range of 1–7 emu g−1. The minimum reflection loss reached −27.5 dB at 13.8 GHz with a matching layer thickness of 2.0 mm and an effective absorption bandwidth (< −10 dB) of about 4.1 GHz (12.0–16.1 GHz). The excellent microwave absorbing performance of this nanocomposite is due to proper impedance matching and the synergistic interaction of dielectric loss, the magnetic loss, and core–shell microstructure. Moreover, the electromagnetic and microwave absorbing properties of γ-Fe2O3–SiO2–PEDOT nanocomposites can be regulated by changing the dosage of functionalized γ-Fe2O3–SiO2.

Synthesis of quasi-core–shell Co-doped ZnO/graphene nanoparticles

Co-doped ZnO/graphene quasi-core–shell hybrid nanoparticles with a reduced graphene oxide (RGO) shell around the Zn0.98Co0.02O core are synthesized by a facile chemical process. X-ray diffraction (XRD) analysis reveals that nanoparticles consist of wurtzite ZnCoO and graphene without the impurity phase. The successful doping of Co ions into the ZnO host is illustrated by the XRD lines shifting and XPS spectra of Co ions. High-resolution transmission electron microscopy (HRTEM) image shows that the Zn0.98Co0.02O is fully covered with the RGO shell, verifying that Zn0.98Co0.02O/RGO hybrid structure is quasi-core–shell structure. Raman spectra indicate that graphene oxide is reduced to graphene successfully. The red-shift of the characteristic E2H peak and 2D peak of Zn0.98Co0.02O/RGO imply the electron interaction between Zn0.98Co0.02O and RGO. Magnetization measurement demonstrates that the Zn0.98Co0.02O/RGO nanoparticles present canted antiferromagnetic behavior, which has a promising application in semiconductor spintronic devices.

Synthesis of FeCo nanoparticles from FeO(OH) and Co3O4 using oleic acid as reduction agent

A facile chemical process has been developed for the preparation of magnetic FeCo nanoparticles. The FeCo nanoparticles were mono-dispersed, obtained by the safe and ecofriendly method, possessed saturation magnetization up to 187 emu/g, and demonstrated excellent chemical stability. In this work, we have studied how to control Fe/Co ratio by variation of precursor ratio, and how to vary particle size from 9.3 to 12.3 nm by surfactant amount used. The cytotoxicity of as-synthesized nanoparticles was investigated after coating with the poly(methyl methacrylate-co-butyl acrylate) by the emulsion process and the results demonstrated high biocompatibility. Similarly, the same synthesis method was used with the single precursor FeO(OH) or Co3O4. The results showed that this method can also fabricate 10 nm mono-dispersed spherical Fe3O4 particles and self-assembly Co nanoneedles.

Morphology-Dependent Enhancement of the Pseudocapacitance of Template-Guided Tunable Polyaniline Nanostructures

Polyaniline is one of the most investigated conducting polymers as supercapacitor material for energy storage applications. The preparation of nanostructured polyaniline with well-controlled morphology is crucial to obtaining good supercapacitor performance. We present here a facile chemical process to produce polyaniline nanostructures with three different morphologies (i.e., nanofibers, nanospheres, and nanotubes) by utilizing the corresponding tunable morphology of MnO2 reactive templates. A growth mechanism is proposed to explain the evolution of polyaniline morphology based on the reactive templates. The morphology-induced improvement in the electrochemical performance of polyaniline pseudocapacitors is as large as 51% due to the much enhanced surface area and the porous nature of the template-guided polyaniline nanostructures. In addition, and for the first time, a redox-active electrolyte is applied to the polyaniline pseudocapacitors to achieve significant enhancement of pseudocapacitance. Compared to the conventional electrolyte, the enhancement of pseudocapacitance in the redox-active electrolyte is 49%–78%, depending on the specific polyaniline morphology, reaching the highest reported capacitance of 896 F/g for polyaniline full cells so far.

Porous carbon supported Fe–N–C for applications as cathodic electrocatalysts in fuel cells

The carbons incorporating FeNx electrocatalysts (FeTEPA/C-x) were fabricated via a facile chemical process. The nitrogen-rich species (tetraethylenepentamine) were complexed with iron precursors (FeCl3) on carbon blacks (Vulcan XC-72) and treated under high temperature in a nitrogen atmosphere. These resultant catalysts were characterized by a variety of different spectroscopic and analytical techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements. Experimentally, the electrocatalytic performance of oxygen reduction for FeTEPA/C-2.7, which was found to have an approximate four electron transfer, was observed to be surpassing among all FeTEPA/C-x electrocatalysts. This may be attributed to its unique properties, including the higher nitrogen content, more pyridinic-N sites and probable formation of Fe–N–C active centers which were evidenced by XAS.