Halima Begum

A novel δ-MnO2 with carbon nanotubes nanocomposite as an enzyme-free sensor for hydrogen peroxide electrosensing

We have reported the synthesis and application of a δ-MnO2 with carbon nanotubes (δ-MnO2/CNTs) nanocomposite as an enzyme-free sensor for the detection of H2O2 through an electroreduction reaction, where δ-MnO2 serves as the catalytic center and CNTs as the highly conductive base material. The δ-MnO2/CNTs nanocomposite was synthesized via a simple and single-step hydrothermal process in alkaline solution without using any surfactants or templates. The electrochemical properties of the δ-MnO2/CNTs on a glassy carbon electrode were investigated by cyclic voltammetry, and amperometry. It was found that, under optimized conditions, the sensor fabricated electrode provides linear amperometric responses for H2O2 in a large concentration range from 0.05 to 22 mM and a detection limit of 1 μM with a comparatively high sensitivity of 243.9 μA mM−1 cm−2. In addition, the δ-MnO2/CNTs modified GCE exhibits excellent selectivity, and good reproducibility for H2O2 detection. It is promising that the proposed H2O2 sensor can be used as an effective tool to measure the H2O2 in practical samples.

Selective Formation of Heterometallic Ru–Ag Supramolecules via Stoichiometric Control of Multiple Different Tectons

Stoichiometric control of Ru, Ag, and tetrazolyl ligands resulted in the formation of different heterometallic Ru-Ag supramolecular architectures. Although the reaction of Ru and 5-(2-hydroxyphenyl)-1H-tetrazolyl (LH2) in a molar ratio of 2:1 or 6:4 resulted in the formation of dimeric or hexameric Ru complexes, Ag metal ions caused the Ru complexes to form three-dimensional cylindrical Ru6Ag6L6 and double-cone-shaped Ru6Ag8L6 complexes by occupying vacant coordination sites.

New Approach for Porous Chitosan?Graphene Matrix Preparation through Enhanced Amidation for Synergic Detection of Dopamine and Uric Acid

Amide-functionalized materials have emerged as promising nonprecious catalysts for electrochemical sensing and catalysis. The covalent immobilization of chitosan (CS) onto graphene sheet (GS) (denoted as CS–GS) has been done via higher degree of amidation reaction to develop an electrochemical sensing matrix for simultaneous determination of dopamine (DA) and uric acid (UA). The enhanced amidation between CS and GS has not been reported previously. However, electrochemical results have revealed that the CS–GS enhances the electrocatalytic performance in terms of the oxidation potential and peak current due to the higher degree of amide functionalization compared to that of CS/GS, which has a lower amidation. Differential pulse voltammetry-based studies have indicated that the CS–GS matrix works at a lower detection limit (0.14 and 0.17 μM) (S/N = 3) and over a longer linear range (1–700 and 1–800 μM), with a comparatively higher sensitivity (2.5 and 2.0 μA μM–1 cm–2), for DA and UA, respectively. In addition, the CS–GS matrix demonstrates good selectivity toward the detection of DA and UA in the presence of a 10-fold higher concentration of AA and glucose. The as-prepared three-dimensional porous CS–GS also endows selective determination toward DA and UA in various real samples.

Ultra-fast and highly sensitive enzyme-free glucose biosensing on a nickel–nickel oxide core–shell electrode

Correction for ‘Ultra-fast and highly sensitive enzyme-free glucose biosensing on a nickel–nickel oxide core–shell electrode’ by Halima Begum et al., RSC Adv., 2017, 7, 3554–3562.

Highly Efficient Dual Active Palladium Nanonetwork Electrocatalyst for Ethanol Oxidation and Hydrogen Evolution

Tunable palladium nanonetwork (PdNN) has been developed for catalyzing ethanol oxidation reaction (EOR) and hydrogen evolution reaction (HER) in alkaline electrolyte. 3D PdNN is regarded as a dual active electrocatalyst for both EOR and HER for energy conversion application. The PdNN has been synthesized by the simple chemical route with the assistance of zinc precursor and a surfactant (i.e., cetyltrimethylammonium bromide, CTAB). The thickness of the network can be tuned by simply adjusting the concentration of CTAB. Both EOR and HER have been performed in an alkaline electrolyte, and characterized by different voltammetric methods. The 3D PdNN has shown 2.2-fold higher electrochemical surface area than the commercially available Pt/C including other tested catalysts with minimal Pd loading. As a result, it provides a higher density of EOR and HER active sites and facilitated the electron transport. For example, it shows 2.6-fold higher mass activity with significantly lower CO2 production for EOR and the similar overpotential (110 mV @ 10 mA cm-2) for HER compared to Pt/C with better reaction kinetics for both reactions. Thus, the PdNN is proved as an efficient electrocatalyst with better electrocatalytic activity and stability than state-of-the-art Pt/C for both EOR and HER because of the crystalline, monodispersed, and support-free porous nanonetwork.

CCDC 1017827: Experimental Crystal Structure Determination

Related Article: Jung Hee Choi, Ji Yeon Ryu, Yu Jin Park, Halima Begum, Hyoung-Ryun Park, Hee Jin Cho, Youngjo Kim, Junseong Lee|2014|Inorg.Chem.Commun.|50|24|doi:10.1016/j.inoche.2014.10.007