Kaushik Natarajan

Microwave assisted fabrication of a nanostructured reduced graphene oxide (rGO)/Fe2O3 composite as a promising next generation energy storage material

Herein, we report a facile two-step process involving homogenous precipitation followed by microwave assisted reduction to fabricate a rGO–Fe2O3 composite. The applicability of the composite as an electrode material for supercapacitors has been evaluated by a cyclic voltammetry (CV) and galvanostatic charging–discharging (GCD) study. The composite displays excellent supercapacitor performance compared to bare rGO and generates a high specific capacitance of 577.5 F g−1, at a current density of 2 A g−1. A high rate performance is also observed by retaining a specific capacitance of 437.5 F g−1, at a high current density of 10 A g−1. Finally, the electrodes have been analyzed through electrochemical impedance spectroscopy (EIS) to probe the charge transfer characteristics and the results have been found to be consistent with other electrochemical measurements. The remarkable electrochemical performance of the rGO–Fe2O3 composite can be attributed to the positive synergistic effects between rGO platelets and Fe2O3 nanoparticles.

Multifunctional porous NiCo2O4 nanorods: sensitive enzymeless glucose detection and supercapacitor properties with impedance spectroscopic investigations

We report the multipurpose nature of NiCo2O4 nanorods fabricated by a facile two-step method for high-performance glucose sensors and supercapacitors. The nanorods that were obtained were investigated by various physicochemical characterization techniques, which revealed their polycrystallinity, suitable microstructure, high porosity and thermal stability. The nanorods that were synthesized were assembled on a glassy carbon electrode (GCE) with a Nafion support via layer-by-layer assembly (Nafion/NCO/GCE or NNCOGCE). The NNCOGCE that was fabricated was employed as a working electrode for two separate applications, namely, a glucose sensor and a supercapacitor. The NNCOGCE selectively detected glucose in a short amperometric response time (3 s), with a wide dynamic linear range (0.001–0.88 mM), a notable detection limit (63 nM) and high sensitivity (4.710 μA μM−1 cm−2). Moreover, the NNCOGCE exhibited high specific capacitance (980 F g−1 at a current density of 2 A g−1) and excellent rate performance (retention of 71.42% up to 10 A g−1) with a long cycle life (retention of 92% up to 1000 cycles). Finally, the NNCOGCE was studied by electrochemical impedance spectroscopy (EIS) to investigate its charge transfer characteristics for both glucose sensor and supercapacitor applications, and the results were correlated with its amperometric sensing ability, as well as its supercapacitor performance.

Visible-Light-Induced Water Splitting Based on a Novel α-Fe2O3/CdS Heterostructure

In this work, CdS nanoparticles were grown on top of a hematite (α-Fe2O3) film as photoanodes for the photoelectrochemical water splitting. Such type of composition was chosen to enhance the electrical conductivity and photoactivity of traditionally used bare hematite nanostructures. The fabricated thin film was probed by various physicochemical, electrochemical, and optical techniques, revealing high crystallinity of the prepared nanocomposite and the presence of two distinct phases with different band gaps. Furthermore, photoassisted water splitting tests exhibit a noteworthy photocurrent of 0.6 mA/cm2 and a relatively low onset potential of 0.4 V (vs reversible hydrogen electrode) for the composite electrode. The high photocurrent generation ability was attributed to the synergistic interplay between conduction and valence band (VB) levels of CdS and α-Fe2O3, which was further interpreted by J–V curves. Finally, electrochemical impedance spectroscopy investigation of the obtained films suggests that the photogenerated holes could be transferred from the VB of α-Fe2O3 to the electrolyte more efficiently in the hybrid nanostructure.

Emerging Robust Heterostructure of MoS2–rGO for High-Performance Supercapacitors

The intermittent nature of renewable energy resources has led to a continuous mismatch between energy demand and supply. A possible solution to overcome this persistent problem is to design appropriate energy-storage materials. Supercapacitors based on different nanoelectrode materials have emerged as one of the promising storage devices. In this work, we investigate the supercapacitor properties of a molybdenum disulfide-reduced graphene oxide (rGO) heterostructure-based binder-free electrode, which delivered a high specific capacitance (387.6 F g-1 at 1.2 A g-1) and impressive cycling stability (virtually no loss up to 1000 cycles). In addition, the possible role of rGO in the composite toward synergistically enhanced supercapacitance has been highlighted. Moreover, an attempt has been made to correlate the electrochemical impedance spectroscopy studies with the voltammetric analyses. The performance exceeds that of the reported state-of-the-art structures.