Co(II)-Chelated Polyimines as Oxygen Reduction Reaction Catalysts in Anion Exchange Membrane Fuel Cells.

In this paper, a cobalt (Co)-chelated polynaphthalene imine (Co-PNIM) was calcined to become an oxygen reduction reaction (ORR) electrocatalyst (Co-N-C) as the cathode catalyst (CC) of an anion exchange membrane fuel cell (AEMFC). The X-ray diffraction pattern of CoNC-1000A900 illustrated that the carbon matrix develops clear C(002) and Co(111) planes after calcination, which was confirmed using high-resolution TEM pictures. Co-N-Cs also demonstrated a significant ORR peak at 0.

Studies on the Application of Polyimidobenzimidazole Based Nanofiber Material as the Separation Membrane of Lithium-Ion Battery.

Aromatic polyimide has good mechanical properties and high-temperature resistance. Based on this, benzimidazole is introduced into the main chain, and its intermolecular (internal) hydrogen bond can increase mechanical and thermal properties and electrolyte wettability. Aromatic dianhydride 4,4'-oxydiphthalic anhydride (ODPA) and benzimidazole-containing diamine 6,6'-bis [2-(4-aminophenyl)benzimidazole] (BAPBI) were synthesized by means of a two-step method.

2,6-Diaminopyridine-Based Polyurea as an ORR Electrocatalyst of an Anion Exchange Membrane Fuel Cell.

In order to yield more Co(II), 2,6-diaminopyridine (DAP) was polymerized with 4,4-methylene diphenyl diisocyanates (MDI) in the presence of Co(II) to obtain a Co-complexed polyurea (Co-PUr). The obtained Co-PUr was calcined to become Co, N-doped carbon (Co-N-C) as the cathode catalyst of an anion exchange membrane fuel cell (AEMFC). High-resolution transmission electron microscopy (HR-TEM) of Co-N-C indicated many Co-Nx (Co covalent bonding with several nitrogen) units in the Co-N-C matrix.

Electrospun Benzimidazole-Based Polyimide Membrane for Supercapacitor Applications.

A benzimidazole-containing diamine monomer was prepared via a simple one-step synthesis process. A two-step procedure involving polycondensation in the presence of aromatic dianhydrides (4,4'-oxydiphthalic anhydride, ODPA) followed by thermal imidization was then performed to prepare a benzimidazole-based polyimide (BI-PI). BI-PI membranes were fabricated using an electrospinning technique and were hot pressed for 30 min at 200 °C under a pressure of 50 kgf /cm.

Cobalt-Based Cathode Catalysts for Oxygen-Reduction Reaction in an Anion Exchange Membrane Fuel Cell.

A novel cobalt-chelating polyimine (Co-PIM) containing an additional amine group is prepared from the condensation polymerization of diethylene triamine (DETA) and terephthalalehyde (PTAl) by the Schiff reaction. A Co, N-co-doped carbon material (Co-N-C), obtained from two-stage calcination in different gas atmospheres is used as the cathode catalyst of an anion exchange membrane fuel cell (AEMFC). The Co-N-C catalyst demonstrates a CoNx-type single-atom structure seen under high-resolution transmission electron microscopy (HRTEM).

Calcined Co(II)-Chelated Polyazomethine as Cathode Catalyst of Anion Exchange Membrane Fuel Cells.

Polyazomethine (PAM) prepared from the polycondensation between p-phenylene diamine (PDA) and p-terephthalaldehyde (PTAl) via Schiff reaction can physically crosslink (complex) with Co ions. Co-complexed PAM (Co-PAM) in the form of gel is calcined to become a Co, N-co-doped carbonaceous matrix (Co-N-C), acting as cathode catalyst of an anion exchange membrane fuel cell (AEMFC). The obtained Co-N-C catalyst demonstrates a single-atom structure with active Co centers seen under the high-resolution transmission electron microscopy (HRTEM).

Cobalt-Doped Carbon Nitride Frameworks Obtained from Calcined Aromatic Polyimines as Cathode Catalyst of Anion Exchange Membrane Fuel Cells.

Cobalt-doped carbon nitride frameworks (CoNC) were prepared from the calcination of Co-chelated aromatic polyimines (APIM) synthesized from stepwise polymerization of p-phenylene diamine (PDA) and o-phthalaldehyde (OPAl) via Schiff base reactions in the presence of cobalt (II) chloride. The Co-chelated APIM (Co-APIM) precursor converted to CoNC after calcination in two-step heating with the second step performed at 100 °C lower than the first one. The CoNCs demonstrated that its Co, N-co-doped carbonaceous framework contained both graphene and carbon nanotube, as characterized by X-ray diffraction pattern, Raman spectra, and TEM micropictures.

New Inverse Emulsion-Polymerized Iron/Polyaniline Composites for Permanent, Highly Magnetic Iron Compounds via Calcination.

The hydrophilic initiator potassium persulfate (KPS) was converted into a hydrophobic molecule by complexing with cetyltrimethylammonium bromide (CTAB) at both ends of the molecule (CTAPSu). Inverse emulsion polymerization thus proceeded inside micelles dispersed in the affluent toluene with CTAPSu as the initiator. Polyaniline (PANI) formed inside the micelles and entangled with FeO nanoparticles already esterified with oleic acid (OA).

Superparamagnetic, High Magnetic α-Fe & α″-FeN Mixture Prepared from Inverse Suspension-Polymerized FeO@polyaniline Composite.

Oleic acid (OA)-modified FeO nanoparticles were successfully covered with polyanilines (PANIs) via inverse suspension polymerization in accordance with SEM and TEM micrographs. The obtained nanoparticles were able to develop into a ferrite (α-Fe) and α″-FeN mixture with a superparamagnetic property and high saturated magnetization (SM) of 245 emu g at 950 °C calcination under the protection of carbonization materials (calcined PANI) and other iron-compounds (α″-FeN). The SM of the calcined iron-composites slightly decreases to 232 emu g after staying in the open air for 3 months.

Calcined Co(II)-Triethylenetetramine, Co(II)- Polyaniline-Thiourea as the Cathode Catalyst of Proton Exchanged Membrane Fuel Cell.

Triethylenetetramine (TETA) and thiourea complexed Cobalt(II) (Co(II)) ions are used as cathode catalysts for proton exchanged membrane fuel cells (PEMFCs) under the protection of polyaniline (PANI) which can become a conducting medium after calcination. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra clearly reveal the presence of typical carbon nitride and sulfide bonds of the calcined Nitrogen (N)- or Sulfur (S)-doped co-catalysts. Clear (002) and (100) planes of carbon-related X-ray diffraction patterns are found for co-catalysts after calcination, related to the formation of a conducting medium after the calcination of PANI.

Melting and Recrystallization of Copper Nanoparticles Prepared by Microwave-Assisted Reduction in the Presence of Triethylenetetramine.

The small sized copper nanoparticles (Cu-NPs), prepared in the presence of triethylene tetramine (TETA) and assisted with microwave irradiation, have an extremely low melting temperature. Melting of the small sizezd Cu-NPs can be triggered by the heat generated from the e-beam irradiation during SEM and TEM image construction. The dispersed Cu atoms around the agglomerated big Cu particles can undergo recrystallization immediately due to the strong driving force of the huge temperature difference to normal melting temperature (T = 1085 °C).

Polyaniline Based Pt-Electrocatalyst for a Proton Exchanged Membrane Fuel Cell.

Calcination reduction reaction is used to prepare Pt/EB (emeraldine base)-XC72 (Vulcan carbon black) composites as the cathode material of a proton exchange membrane fuel cell (PEMFC). The EB-XC72 core-shell composite obtained from directly polymerizing aniline on XC72 particles is able to chelate and capture the Pt-ions before calcination. X-ray diffraction spectra demonstrate Pt particles are successfully obtained on the EB-XC72 when the calcined temperature is higher than 600 °C.

FeNxC Based Catalysts Prepared by the Calcination of Iron-Ethylenediamine@Polyaniline as the Cathode-Catalyst of Proton Exchange Membrane Fuel Cell.

Calcinated tris(ethylenediamine)iron(III) chloride was used as a non-precious metal catalyst (NPMCs) for a proton exchanged membrane fuel cell (PEMFC) under the protection of polyaniline (PANI), which behaves as both nitrogen source and carbon supporter. The optimal ratio of FeCl/EDA was found to be close to 1/3 under the consideration of the electrocatalytic performance, such as better oxygen reduction reaction (ORR) and higher power density. Two-stage calcination, one at 900 °C in N and the other at 800 °C in mixed gases of N and NH, result in an FeNxC catalyst (FeNC-900-800-A) with pretty high specific surface area of 1098 m·g covered with both micro- and mesopores.

Preparation of Pt-Catalyst by Poly(-phenylenediamine) Nanocomposites Assisted by Microwave Radiation for Proton Exchange Membrane Fuel Cell.

The Pt elements are prepared via the redox reaction with microwave (MW) irradiation in the presence of poly(p-phenylenediamine) (PpPD) which is polymerized on XC72 carbon matrix (PpPD/XC72), behaving as reducing agent. The free primary amines of PpPD are actually converted (oxidized) to secondary ones (5,10-dihydrophenazine) after MW irradiation. Transmission electronic microscopy (TEM) micrographs reveal the prepared Pt nanoparticles are well-dispersed on the carbon matrix like commercial Pt-implanted carbon nanocomposite (Pt/C).

Preparation of sub 3 nm copper nanoparticles by microwave irradiation in the presence of triethylene tetramin.

The preparation of sub 3 nm copper nanoparticles (CuNPs) in ethylene glycol (EG) using triethylene tetramine (TETA) as chelating and reducing agents via a rapid microwave (MW) irradiation is reported. The sub 3 nm CuNPs after MW irradiation are clearly seen from the electronic micrographs. The firm chelation of Cu by TETA is illustrated by the dark blue color of Cu/TETA/EG solution and the redox reaction is confirmed by the appearance of red color of the mixtures.

Microwave Assisted Reduction of Pt-Catalyst by N-Phenyl-p-Phenylenediamine for Proton Exchange Membrane Fuel Cells.

The presence of -phenyl--phenylenediamine (PPDA: a dimer of aniline) during microwave (MW) irradiation can significantly improve Pt-loading on the XC72 carbon matrix as a catalyst support of proton exchange membrane fuel cells (PEMFCs). PPDA is converted to an emeraldine base state during MW-assisted redox reaction, which is characterized by both FTIR and Raman spectra. The increased degree of conjugation from the formation of quinone-state of PPDA is confirmed by UV-VIS spectra.

Enhancing growth and proliferation of human gingival fibroblasts on chitosan grafted poly (epsilon-caprolactone) films is influenced by nano-roughness chitosan surfaces.

The bioactivity of poly (epsilon-caprolactone) (PCL) films is improved by grafting chitosan (CS) surfaces with various values of nano-roughness on PCL surfaces. To examine the effects of the design, growing human gingival fibroblasts (HGFs) on the films was conducted. Various values of nano-rough CS surfaces were cast using nano-rough PCL molds that had been fabricated using a solvent-etched technique.

Poly (epsilon-caprolactone) grafted with nano-structured chitosan enhances growth of human dermal fibroblasts.

Polyester films are modified with their bioactivity for tissue engineering by grafting a nano-structured bioactive material, nano-structured chitosan (nano-CS), on a model polymer, poly (epsilon-caprolactone) (PCL). The nano-CS was duplicated using a solvent-etched PCL mold and then grafted onto PCL using a selected solvent. The structure of the nano-CS/PCL surface was characterized using an atomic force microscope to observe the topography and determine the roughness.