Cyclic
voltammetry has been used to investigate the interaction
between reduced graphene oxide (r-GO) and CdTe quantum dots (Q-CdTe).
For that, the composite of Q-CdTe with r-GO (r-GO-CdTe) was prepared
by carrying out the reduction of graphene oxide and the synthesis
of Q-CdTe simultaneously, in a single bath. r-GO-CdTe was characterized
by UV–visible, steady state fluorescence, time-resolved fluorescence,
X-ray diffraction (XRD), Raman, and transmission electron microscopy
(TEM). Cyclic voltammetry was employed to determine the quasi-particle
gap and band edge parameters of Q-CdTe and r-GO-CdTe. The blue shifts
in the quasi-particle gap of r-GO-CdTe have been attributed to the
strong interaction of graphene with CdTe. These interactions were
further verified by time-resolved fluorescence and Raman spectroscopy
which suggested strong electronic coupling between Q-dots and graphene.
We report the optimized synthesis and electrochemical characterization of a composite of few-layered nanostructured MoS2 along with an electroactive metal oxide BiVO4. In comparison to pristine BiVO4, and a composite of graphene/BiVO4, the MoS2/BiVO4 nanocomposite provides impressive values of charge storage with longer discharge times and improved cycling stability. Specific capacitance values of 610 Fg−1 (170 mAhg−1) at 1 Ag−1 and 166 Fg−1 (46 mAhg−1) at 10 Ag−1 were obtained for just 2.5 wt% MoS2 loaded BiVO4. The results suggest that the explicitly synthesized small lateral-dimensioned MoS2 particles provide a notable capacitive component that helps augment the specific capacitance. We discuss the optimized synthesis of monoclinic BiVO4, and few-layered nanostructured MoS2. We report the discharge capacities and cycling performance of the MoS2/BiVO4 nanocomposite using an aqueous electrolyte. The data obtained shows the MoS2/BiVO4 nanocomposite to be a promising candidate for supercapacitor energy storage applications.
Storage of solar radiation is currently accomplished by coupling two separate devices, one that captures and converts the energy into an electrical impulse (a photovoltaic cell) and another that stores this electrical output (a battery or a supercapacitor electrochemical cell). This configuration however has several challenges that stem from a complex coupled-device architecture and multiple interfaces through which charge transfer has to occur. As such presented here is a scheme whereby solar energy capture and storage have been coupled using a single bi-functional material. Two electroactive semiconductors BiVO4 (n-type) and Co3O4 (p-type) have been separately evaluated for their energy storage capability in the presence and absence of visible radiation. Each of these have the capability to function as a light harvester and also they have faradaic capability. An unprecedented aspect has been observed in that upon photo-illumination of either of these semiconductors, in situ charge carriers being generated play a pivotal role in perturbing the electroactivity of the redox species such that the majority charge carriers, viz. electrons in BiVO4 and holes in Co3O4, influence the redox response in a disproportionate manner. More importantly, there is an enhancement of ca. 30% in the discharge capacity of BiVO4 in the presence of light and this directly provides a unique route to augment charge storage during illumination.
Transition metal sulphides have been viewed as alternatives to platinum based electrocatalysts for HER. Herein, we report the preparation of Ni3S2 in conjunction with Ni in a novel nanosheet morphology and verified its performance for HER. During cyclic polarization, exotic morphological transformation of Ni3S2‐Ni from nanosheets to nanodisks has been noted. This change is accompanied with initial increase in over‐potential that passed through maxima (∼ 100mV above the starting potential) and decreased to ∼ 50mV below the starting value. Enhanced electrocatalytic activity due to the morphological changes from sheets to nanodisks has been attributed to the formation of more number of exposed edge‐planes known to promote HER. Kinetic analysis based on Tafel slope displayed by this composite is comparable to that of Pt based catalysts.
We illustrate that the extent of hydration and consequently the heat of hydration of alkali metal ions can be utilized to control their insertion/deinsertion chemistry in a redox active metal coordination polymer framework (CPF) electrode. The formal redox potential of CPF electrode for cation intercalation is inversely correlated to hydrated ionic radii, with clear distinction between the intercalation of ions across alkali metal series. This leads to noninvasive identification and differentiation of cations in the alkali metal series by utilizing a single sensing platform.
Synthesis of organic molecules by utilizing the principles of electrochemistry satisfies 9 out of the 12 postulates of green chemistry, conferring electrochemical synthetic methodologies with clean, safe, and green tags. However, electro-organic synthesis is a heterogeneous interfacial reaction demanding significant driving force in terms of voltage or current. Here, we demonstrate an unusual route for electro-organic synthesis during electricity generation in a battery, where the positive half-cell is designed to function as an organic reactor generating useful chemicals and fuel molecules. The proposed electroorganic synthesizer Zn battery couples organic synthesis with power production during discharge chemistry, thereby demonstrating its tremendous potential in the sustainable energy landscape.
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