Coauthored Publications with: Rajkumar

Journal Article

Veerakumar, P, Rajkumar C, Chen S-M, Thirumalraj B, Lin K-C.  2018.  Activated porous carbon supported rhenium composites as electrode materials for electrocatalytic and supercapacitor applications. Electrochimica Acta. 271:433-447. AbstractWebsite

In this study, we developed highly dispersed rhenium nanoparticles decorated on activated carbon (Re@CDACs). The activated carbons were derived from the biomass raw materials cardamom pods (Elettaria cardamomum L) via carbonization followed by activation with ZnCl2 at high temperature. The Re NPs synthesis was achieved by decomposition of [Re2(CO)10] complex via a facile microwave thermal reduction technique. The as-prepared Re@CDACs nanocomposites were characterized by a combination of state-of-the-art techniques. The Re@CDACs nanocomposites so prepared were utilized for electrocatalytic oxidation of sunset yellow (SY) and supercapacitor applications. The Re@CDACs-modified electrodes were found to show extraordinary electrochemical performance for sensitive and selective detection of SY with a wide linear range of 0.05–390 μM and a detection limit and sensitivity of 16 nM (S/N = 3) and 91.53 μA μM−1, respectively, surpassing other modified electrodes. Moreover, these Re@CDACs catalysts were also found to exhibit a higher specific capacitance of 181 F g-1 at a current density of 1.6 A g−1 in 1.0 M H2SO4 electrolyte. The specific capacitance retention of 90% was achieved after 2500 cycles at current density 2.0 A g−1. Therefore, we have demonstrated that the Re@CDACs nanocomposite materials could be used as a promising electrode material in electrochemical oxidation of SY and energy storage applications. © 2018
Veerakumar, P, Rajkumar C, Chen S-M, Thirumalraj B, Lin K-C.  2018.  Ultrathin 2D graphitic carbon nitride nanosheets decorated with silver nanoparticles for electrochemical sensing of quercetin. Journal of Electroanalytical Chemistry. 826:207-216. AbstractWebsite

In this work, we describe a facile fabrication of silver nanoparticles decorated on porous ultrathin two dimensional (2D) graphitic carbon nitride nanosheets (AgNPs@g-CN) via chemical approach, which was characterized by various analytical techniques including cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry. As expected, the AgNPs@g-CN modified glassy carbon electrode (AgNPs@g-CN/GCE) exhibited remarkable electrocatalytic activity towards the detection of quercetin (QCR) with a wide linear range from 1.0 × 10−8 to 1.2 × 10−4 mol L−1 and a lower detection limit of 6.0 × 10−9 mol L−1. Besides, the amperometric results revealed that the peak current for QCR could not affect upon the sequential additions of electroactive interfering species such as metal ions (300 μM), biomolecules (100 μM), and other flavonoids (50 μM) indicating the selectivity of the proposed sensor. Moreover, the AgNPs@g-CN modified electrode displayed higher stability and reproducibility towards the detection of QCR. The AgNPs@g-CN/GCE could also be used to detect QCR in green apple (GA) samples with satisfactory recoveries for practical applications. The concepts behind the novel architecture to modify electrodes can be potentially harnessed in other electrochemical sensors and photocatalysis applications. © 2018 Elsevier B.V.
Sangili, A, Veerakumar P, Chen S-M, Rajkumar C, Lin K-C.  2019.  Voltammetric determination of vitamin B2 by using a highly porous carbon electrode modified with palladium-copper nanoparticles. Microchimica Acta. 186(5):299. AbstractWebsite

Palladium-copper nanoparticles were placed on activated carbon to give a nanocomposite for electrochemical sensing of riboflavin (vitamin B 2 ). The activated carbon was produced by pyrolysis of natural waste of pistachio nutshells after KOH activation and under a nitrogen atmosphere. The carbons possess a large surface area and micro/meso-porosity. The nanocomposite was characterized by a variety of techniques to confirm structures and morphology. A screen-printed electrode modified with the composite was examined by EIS, CV, DPV, and amperometry. The effects of pH value, scan rate, and stability of the modified electrode were studied. Under optimized conditions, vitamin B 2 displays a well-expressed oxidation peak at −0.15 V (vs. Ag/AgCl) in solutions with a pH value of 7.0. The voltammetric signal increases linearly in the 0.02 to 9 μM concentrations range and a lower detection limit of 7.6 pM. The sensor was successfully applied to the determination of vitamin B 2 even in the presence of other common vitamins and in (spiked) raw milk samples. [Figure not available: see fulltext.]. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature.