Vikrant Sahu

Developing low cost and high energy density negative electrode materials without deterioration of the environment is an imperative need in the area of energy storage. Here, encapsulation of MoO₃ nanoflowers (MO) in activated carbon (AC) derived from biomass i.e. a loofah sponge is envisioned to accomplish the synthesis of a cost effective and highly capacitive negative electrode for supercapacitors. AC derived from a loofah sponge inherited the structure with plenty of meso/macropores and oxygen functionalities to anchor MoO₃ (∼50 nm dia.), while the nanoflower configuration of particles offers adequate interfacial active sites for charge storage. The oxygen functionalities of AC together with the intercalation/diffusive ability of MoO₃ (MO) in the composite (20 AC-MO) lead to splendid performance (413 F g⁻¹@8 A g⁻¹) compared to AC (102.89 F g⁻¹@8 A g⁻¹). More significantly, 20 AC-MO shows remarkable improvement in energy density (52.87 W h kg⁻¹@3.8 kW kg⁻¹) compared to AC (12.62 W h kg⁻¹@3.7 kW kg⁻¹). Herein, the blend of the capacitive mechanism with the pseudo-intercalation mechanism is adopted to improve the charge storage ability of the negative electrode. Consequently the highly capacitive negative electrode can potentially improve the asymmetric supercapacitor performance for future applications.

Tuberculosis is one of the most dreadful diseases caused by Mycobacterium tuberculosis with more than 9 million individuals suffering from it in 2014. Traditional methods of detection are not efficient enough for its quick and reliable detection; therefore, it is imperative to develop methods of its detection in the early stages. Consequently, we report a highly sensitive and selective biosensor for detection of Mycobacterium tuberculosis. In this work, gold nanoparticles (AuNPs, dia. ∼6 nm, 1.81 wt% loading) are immobilized over reduced graphene oxide nanoribbons (RGONRs). An ssDNA/Au/RGONR electrode is prepared by immobilizing Au nanoparticles followed by covalent modification of Au nanoparticles with 5′SH-ssDNA. As per the best knowledge of the authors, the target DNA of Mycobacterium tuberculosis is detected using a ssDNA/Au/RGONR bioelectrode by cyclic voltammetry and chronoamperometric methods for the first time. With high detection efficiency (0.1 fM), the ssDNA/Au/RGONR bioelectrode exhibited better signal amplification and electrochemical response as compared to bare Au and RGONR electrodes. Additionally, the ssDNA/Au/RGONR bioelectrode displayed good linear response to different concentrations of target M. tuberculosis DNA. The ssDNA/Au/RGONR has shown excellent specificity (92%) to Mycobacterium tuberculosis target DNA as compared with non-complementary DNA. The Au/RGONR matrix has the potential to be used as an immobilization platform for single-stranded probe DNAs of different diseases other than tuberculosis reported here.