No abstract

In this work, the synthesis of high-performance, metal ion-imprinted, mesoporous carbon electrocatalysts for hydrazine oxidation reaction (HzOR) using casein or a family of phosphoproteins derived from cow's milk as a precursor is shown. The synthesis is made possible by mixing trace amounts of non-noble metal ions (Fe 3+ or Co 2+ ) with casein and then producing different metal ions-functionalized casein intermediates, which upon carbonization, followed by acid treatment, lead to metal ionimprinted catalytically active sites on the materials. The materials effectively electrocatalyze HzOR with low overpotentials at neutral pH and exhibit among the highest electrocatalytic performances ever reported for carbon catalysts. Their catalytic activities are also better than the corresponding control material, synthesized by carbonization of pure casein and other materials previously reported for HzOR. This work demonstrates a novel synthetic route that transforms an inexpensive protein to highly active carbon-based electrocatalysts by modifying its surfaces with trace amounts of non-noble metals. The types of metal ions employed in the synthesis are found to dictate the electrocatalytic activities of the materials. Notably, Fe 3+ is found to be more effective than Co 2+ in helping the conversion of casein into more electrocatalytically active carbon materials for HzOR.

Ionic liquid-modified cellulose nanowhiskers are synthesized and successfully used as precursors to make heteroatom-doped carbon catalysts.

Hybrid nanostructured materials comprised amorphous carbon nanoneedles (CNN)-supported Co3O4 nanoparticles (Co3O4-CNN) were synthesized. The synthesis involved layer-by-layer nanocasting of cellulose nanowhiskers with cobalt oxide and silica precursors, followed by pyrolysis of the core-shell-shell composite materials and etching of the outer silica shells off of the carbonized materials. Notably, cotton-derived cellulose nanowhiskers were used as the carbon precursors, and also as the hard templates for needle-shaped carbons, in the synthesis. The effectiveness of the core-shell-shell nanoreactors, possessing the silica shell-entrapped cellulose nanowhiskers and Co(II) ions, in generating organized carbon nanomaterials with metal oxide nanoparticles, or otherwise, as a function of the loading of Co(II) ions was evaluated. Details of the synthetic method and the different materials in terms of composition and morphology it results in as a function of the relative amount of metal ions have also been discussed. The materials showed promising supercapacitive properties and electrocatalytic activity for oxygen reduction reaction (ORR). The materials' double layer capacitance and performance for ORR electrocatalysis as a function of their Co3O4 content and particles size have also been discussed. The results indicated that the electrochemical properties of these hybrid materials are strongly related to the morphology of their carbon nanostructures. The synthetic method demonstrated here can potentially serve as a facile route to produce other metal oxide/carbon nanomaterials, with different morphology and similar or better properties, using other carbon precursors. 16,17

An inorganic/organic hybrid material with triggering mechanism for specific drug delivery at colon is demonstrated. First, hydroxyapatite nanowhiskers (n-HA) with high aspect ratio, narrow particle size distribution and high surface area, ca. 67 m 2 /g, are prepared. As a proof-of-concept, terbinafine, a fungicidal agent, is loaded onto the n-HA, obtaining a drug loading of 40.63 mg of terbinafine per gram of n-HA. Hydroxyapatite nanowhiskers loaded with terbinafine are encapsulated with chondroitin sulfate (CS) microspheres, using chemically modified glycidyl methacrylate by performing ultrasonic microemulsion polymerization. The obtained hybrid materials were characterized by TEM, SEM, FTIR, and NMR. Dispersed n-HA in CS microspheres are obtained for different n-HA contents, from 1 to 10% (%w/w). Terbinafine release from hybrid microspheres is caried out by in vitro studies in simulated gastric fluid and simulated intestinal fluid. The studies demonstrated that sustained drug release can be obtained using the developed hybrid material.