Arumugam Manikandan

Honeycomb-like Porous Carbon–Cobalt Oxide Nanocomposite for High-Performance Enzymeless Glucose Sensor and Supercapacitor Applications

Herein, we report the preparation of Pongam seed shells-derived activated carbon and cobalt oxide (∼2-10 nm) nanocomposite (PSAC/Co3O4) by using a general and facile synthesis strategy. The as-synthesized PSAC/Co3O4 samples were characterized by a variety of physicochemical techniques. The PSAC/Co3O4-modified electrode is employed in two different applications such as high performance nonenzymatic glucose sensor and supercapacitor. Remarkably, the fabricated glucose sensor is exhibited an ultrahigh sensitivity of 34.2 mA mM(-1) cm(-2) with a very low detection limit (21 nM) and long-term durability. The PSAC/Co3O4 modified stainless steel electrode possesses an appreciable specific capacitance and remarkable long-term cycling stability. The obtained results suggest the as-synthesized PSAC/Co3O4 is more suitable for the nonenzymatic glucose sensor and supercapacitor applications outperforming the related carbon based modified electrodes, rendering practical industrial applications.

Wafer Scale Phase-Engineered 1T-and 2H-MoSe2/Mo Core-Shell 3D-Hierarchical Nanostructures toward Efficient Electrocatalytic Hydrogen Evolution Reaction

The necessity for new sources for greener and cleaner energy production to replace the existing ones has been increasingly growing in recent years. Of those new sources, the hydrogen evolution reaction has a large potential. In this work, for the first time, MoSe2 /Mo core-shell 3D-hierarchical nanostructures are created, which are derived from the Mo 3D-hierarchical nanostructures through a low-temperature plasma-assisted selenization process with controlled shapes grown by a glancing angle deposition system.

Thermally Strained Band Gap Engineering of Transition Metal Dichalcogenide Bilayers with Enhanced Light-Matter Interaction toward Excellent Photodetectors

Integration of strain engineering of two-dimensional (2D) materials in order to enhance device performance is still a challenge. Here, we successfully demonstrated the thermally strained band gap engineering of transition-metal dichalcogenide bilayers by different thermal expansion coefficients between 2D materials and patterned sapphire structures, where MoS2 bilayers were chosen as the demonstrated materials. In particular, a blue shift in the band gap of the MoS2 bilayers can be tunable, displaying an extraordinary capability to drive electrons toward the electrode under the smaller driven bias, and the results were confirmed by simulation. A model to explain the thermal strain in the MoS2 bilayers during the synthesis was proposed, which enables us to precisely predict the band gap-shifted behaviors on patterned sapphire structures with different angles. Furthermore, photodetectors with enhancement of 286% and 897% based on the strained MoS2 on cone- and pyramid-patterned sapphire substrates were demonstrated, respectively.

Perovskite Quantum Dots with Near Unity Solution and Neat‐Film Photoluminescent Quantum Yield by Novel Spray Synthesis

In this study, a novel perovskite quantum dot (QD) spray-synthesis method is developed by combining traditional perovskite QD synthesis with the technique of spray pyrolysis. By utilizing this new technique, the synthesis of cubic-shaped perovskite QDs with a homogeneous size of 14 nm is demonstrated, which shows an unprecedented stable absolute photoluminescence quantum yield ≈100% in the solution and even in the solid-state neat film. The highly emissive thin films are integrated with light emission devices (LEDs) and organic light emission displays (OLEDs). The color conversion type QD-LED (ccQD-LED) hybrid devices exhibit an extremely saturated green emission, excellent external quantum efficiency of 28.1%, power efficiency of 121 lm W-1 , and extraordinary forward-direction luminescence of 8 500 000 cd m-2 . The conceptual ccQD-OLED hybrid display also successfully demonstrates high-definition still images and moving pictures with a 119% National Television System Committee 1931 color gamut and 123% Digital Cinema Initiatives-P3 color gamut. These very-stable, ultra-bright perovskite QDs have the properties necessary for a variety of useful applications in optoelectronics.

Graphene-coated copper nanowire networks as a highly stable transparent electrode in harsh environments toward efficient electrocatalytic hydrogen evolution reactions

Copper nanowire networks (NWs) coated with a graphene layer through a carbon-enclosed chemical vapor deposition technique at a low temperature of 400 °C with a low sheet resistance of 23.2 Ω sq−1 and a high transmittance of 83.4%, which is comparable to the typical values of tin-doped indium oxide (ITO), as a transparent conducting electrode were demonstrated. The graphene-coated copper NW networks retain a low sheet resistance of less than 25 Ω sq−1 even after annealing at a temperature of 240 °C in a pure oxygen environment for 1 h, while a sheet resistance less than 100 Ω sq−1 can still be maintained in natural sea water, and acidic and basic solutions. Their highly stable features in harsh environments make these graphene-coated copper nanowire networks suitable as a catalyst toward high-efficiency hydrogen evolution reactions (HERs) with a low overpotential of 252 mV at 10 mA Cm−2 and a low Tafel slope of 67 mV dec−1. The non-corrosive and anti-oxidant graphene-coated copper nanowire networks could be used as an alternative transparent conducting electrode in harsh environments, such as in tandem photocatalytic water splitting.

A superior dye adsorbent towards the hydrogen evolution reaction combining active sites and phase-engineering of (1T/2H) MoS2/α-MoO3 hybrid heterostructured nanoflowers

Here, we demonstrate the successful synthesis of (1T/2H) MoS2/α-MoO3 heterostructured nanoflowers at a low temperature of 200 °C by a one-step hydrothermal method. By tuning the reaction time under the influence of thiourea and hydrazine hydrate, we established a complete phase-engineered MoS2 with 1T and 2H phases on the surface of α-MoO3. Active sites associated with the phase-engineered (1T/2H) MoS2/α-MoO3 hybrid nanoflowers enable them to exhibit dual roles as a superior dye adsorbent and an electrocatalyst towards the hydrogen evolution reaction. The 2H-rich (1T/2H) MoS2/α-MoO3 hybrid heterostructured nanoflowers prepared at 16 h achieved a high surface area of 37.97 m2 g−1, and 97% of the RhB dye with an initial concentration of 47.9 mg L−1 was removed within 10 min through the adsorption process, which is the highest known removal efficiency reported in the literature. As a hydrogen evolution reaction (HER) electrocatalyst in acidic solution, the 1T-rich (1T/2H) MoS2/α-MoO3 hybrid heterostructured nanoflowers prepared at 12 h exhibited a highly efficient catalytic activity by achieving a low overpotential of 232 mV at a current density of 10 mA cm−2, which is comparable to those of previously reported HER catalysts based on MoS2. Moreover, this sample reached a low Tafel slope of 81 mV dec−1 and was stable when operated for more than 1000 cycles.