Publication: Scientific Reports, Volume 9, Article 5650, pp. 1-13, 2019

Abstract: Supercapacitors are beneficial as energy storage devices and can obtain high capacitance values greater than conventional capacitors and high power densities compared to batteries. However, in order to improve upon the overall cost, energy density, and charge-discharge rates, the electrode material of supercapacitors needs to be fine-tuned with an inexpensive, high conducting source. We prepared a Co(III) complex and polypyrrole (PPy) composite thin films (CoN₄–PPy) that was electrochemically deposited on the surface of a glassy carbon working electrode. Cyclic voltammetry studies indicate the superior performance of CoN₄-PPy in charge storage in acidic electrolyte compared to alkaline and organic solutions. The CoN₄-PPy material generated the highest amount of specific capacitance (up to 721.9 F/g) followed by Co salt and PPy (Co-PPy) material and PPy alone. Cyclic performance studies showed the excellent electrochemical stability of the CoN₄-PPy film in the acidic medium. Simply electrochemically depositing an inexpensive Co(III) complex with a high electrically conducting polymer of PPy delivered a superior electrode material for supercapacitor applications. Therefore, the results indicate that novel thin films derived from Co(III) metal complex and PPy can store a large amount of energy and maintain high stability over many cycles, revealing its excellent potential in supercapacitor devices.

The post Simultaneous Electrochemical Deposition of Cobalt Complex and Poly(pyrrole) Thin Films for Supercapacitor Electrodes appeared first on Center for Integrative Nanotechnology Sciences.

Publication: Nanotechnology. 2017 Jan 6;28(1):015101. Epub 2016 Nov 28.

Abstract:

A major benefit to nanomaterial based-medicine is the ability to provide nanosized vehicles for sporadic metabolites. Here, we describe how the conjugation of valuable ginseng secondary metabolites (ginsenoside Rb1 or Rg1) with carbon nanotubes (CNT) can enhance their anti-proliferative and anti-cancer effects. Ginsenoside-CNT conjugate (Rb-CNT or Rg-CNT) permitted the ginsenosides to be used at a low dose, yet achieve a higher incidence of cancer killing. We were able to demonstrate that the ginsenoside-CNT conjugate can decrease cell viability up to 62% in breast cancer cells (MCF-7) and enhance antiproliferation of drug-resistant pancreatic cancer cells (PANC-1) by 61%. The interaction of the ginsenoside-CNT conjugate with breast cancer cells was studied using Raman Spectroscopy mapping. Total transcriptome profiling (Affymetrix platform) of MCF-7 cells treated with the ginsenoside-CNT conjugate shows that a number of cellular, apoptotic and response to stimulus processes were affected. Therefore, our data confirmed the potential use of CNT as a drug delivery system.

The post Carbon nanotubes as carriers of Panax ginseng metabolites and enhancers of ginsenosides Rb1 and Rg1 anti-cancer activity appeared first on Center for Integrative Nanotechnology Sciences.

Publication: ACS Sustainable Chemistry and Engineering, Issue 3, Volume 1

Abstract:

A nanocomposite of a dichloro-amido-macrocyclic cobalt(III) complex (1) and graphene was developed and characterized using various microscopic and spectroscopic techniques such as X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and Raman spectroscopy. The nanocomposite was evaluated for electrocatalytic activity toward oxygen reduction reaction (ORR) in fuel cell applications. This complex (1) showed efficiency in a wide range of pH (acidic and basic) conditions for successful ORR. Apart from pH studies, the ratio of electrocatalyst 1 to graphene was varied for developing the optimal ORR catalyst. The use of graphene as a carbon support along with 1 in ORR studies not only resulted in increased current density but also a positive shift of the reduction potential by 140 mV (with respect to the Ag/AgCl reference electrode). Investigation of the catalytic mechanism using rotating disk electrode and rotating ring-disk electrode studies revealed its mechanism in acidic and basic conditions. The ORR was found to be a four-electron process in both pH conditions. The rate constant of ORR activity was found to be 3.85 × 10⁵ mol^–1s^–1 at pH 2.0. The efficiency of the nanocomposite in ORR indicates the advantage of using both 1 and graphene for fuel cell applications.

The post Graphene-Enhanced Oxygen Reduction by MN4 Type Cobalt (III) Catalyst appeared first on Center for Integrative Nanotechnology Sciences.

Publication: Energy Technology, Volume 2, Issue 7

Abstract:

We present the successful synthesis of a modified poly(3-hexyl)thiophene (P3HT) donor polymer with benzophenone (P3HTB) substitution. The triplet-sensitizer (benzophenone)-containing polymer (P3HTB) was synthesized by the oxidative copolymerization of 3-hexylthiophene and benzopheneone-modified thiophene [2-phenyl-2-(4-(thiophen-3-yl)phenyl)-1,3-dioxolane] and deprotecting the cyclic ketal group. The resulting polymer was characterized by using nuclear magnetic resonance spectroscopy (¹H NMR and ¹³C NMR) and Fourier transform infrared spectroscopy (FTIR). Different ratios of the copolymer (P3HTB) and pristine P3HT mixtures were used for the fabrication and characterization of bulk heterojunction (BHJ) cells, with [6,6]-Phenyl C₆₁ butyric acid methyl ester (PCBM) used as the acceptor in fabricating the active layers. An increase in power conversion efficiency (≈15 %) was observed with devices fabricated with 2.5 and 5 wt % P3HTB mixed with P3HT compared to those fabricated with P3HT alone.

The post Triplet Sensitizer Modification of Poly(3-hexyl)thiophene (P3HT) for Increased Efficiency in Bulk Heterojunction Photovoltaic Devices appeared first on Center for Integrative Nanotechnology Sciences.