Production
of H2 fuel from photocatalytic splitting
of water is one of the most demanding research studies in terms of
sustainable development in the energy sector. In our quest to find
an effective photocatalyst for H2 production, we prepared
graphene quantum dots/TiO2-based nanocomposites using a
simple hydrothermal method and studied the effect of varying morphologies
of TiO2 on photocatalytic H2 production. The
crystal structure, morphology, surface, and optical properties were
thoroughly studied by using X-ray diffraction and different spectroscopic
and electron microscopic techniques. The outcome of the comparative
study by using various graphene quantum dots/TiO2 nanocomposites
found that P-25 TiO2-based nanocomposite gives the highest
rate of H2 production among all with 29,548 μmol
g–1 h–1 and is almost 14 times
efficient compared to pristine P-25 TiO2. It was also evident
from the characterization results that the morphology and biphasic
nature of TiO2 play a crucial role in H2 production.
The plausible reaction mechanism explained the dual role (cocatalyst
and sensitizer) of graphene quantum dots on TiO2 nanoparticles
and beneficial properties of biphasic TiO2 as an efficient
charge transfer mechanism. The prepared photocatalysts also exhibited
good stability, which was examined for four cycles with a time period
of 4 h, making them feasible candidates for practical applications
in the future.
With a huge upsurge in the energy requirements all over the world, development of energy storage devices with high safety standards without compromising the ecological aspects has become the need of the hour, that propelled the scientific community to search for alternative yet promising sources of energy that would prevent the exhaustion of natural resources. Numerous attempts have been undertaken to utilize the renewable biopolymers in the evolution of solid‐ state electrolytes, as a substitute for liquid electrolytes which are prone to cause leakage leading to hazardous accidents. Despite strenuous efforts, it is still challenging to strike a right balance between the biopolymer elements and the conducting additives. In this review, we aim to lay out a recap on the progress achieved in recent times by employing biopolymers as electrolyte components and its future prospects, that would assist the researchers across the globe to inch one step closer in their quest to find the best electrolyte system for flexible electronics.
To address the present need in forensic security perceptions, including the ability to detect latent fingerprints, designing and development of low‐cost fluorescent materials becomes inevitable. This work illustrates the preparation of ZnO and its nanocomposite, Zn−CD with nitrogen doped carbon dots (CD−GC) with all components being generated from a single natural precursor, “Gynura Cusimba”. Cell viability experiment carried out on HEK 293T cell line revealed that CD−GC, pure ZnO nanoparticles, and Zn−CD_0.8 were all biocompatible after being suitably evaluated by various analytical methods. Zn−CD_0.8 nanopowder was useful in detecting level 1–3 features of latent fingerprint developed on several substrates, which displayed good contrast and visibility. The work also highlights the application of Zn−CD_0.8 nanopowder for real time detection of latent fingerprints by demonstrating its use to identify aged fingerprints and those immersed in water. The results indicate that the potential of Zn−CD_0.8 to be a reasonably priced alternative to the existing commercial powders.
This review outlines the significance of recent findings regarding PANI-based composites, the corresponding synthetic strategies, and their role as electrode materials in the enhancement of the electrochemical performance of flexible supercapacitors.
Industrial pollutants are one of the many contributing factors towards deterioration of nature, urging the scientific community around the globe to look for ways in which they can be eliminated. In this regard, we have developed and optimized an efficient photocatalytic system comprising of liquid exfoliated graphene quantum dots (GQDs) and TiO 2 , by carrying out a thorough study with different morphologies of TiO 2 ; namely, nanotubes, nanorods and nanoparticles. The nanocomposites were duly characterized using various techniques such as FT-IR, TGA, FESEM, UV-vis spectroscopy etc. Among the as-prepared range of nanocomposites, the photocatalyst containing 2 wt% of GQDs and TiO 2 nanotubes was found to exhibit a higher degradation efficiency of 96.7 % towards methylene blue (MB) under visible light irradiation of 120 min. Further, we have also repeated the photocatalytic study of this nanocomposite up to four cycles to understand the reusability of the photocatalyst. Band gap of GQDs, pristine TiO 2 and the nanocomposite determined from Tauc plot was found to be 2.26, 2.92 and 2.86 eV respectively. We also underline that the "metal-free" GQDs, synthesized via our approach, play the role of a photosensitizer by providing an edge of extending the visible light absorption in the case of nanocomposites via enhanced electron-hole (e-h) separation and lowering of band gap.
As a fuel, hydrogen may effectively replace the traditional fossil fuels. TiO 2 has been in use the most in semiconductors for photocatalytic hydrogen generation, according to a detailed review of the prior art. In our research, we created a photocatalytic system made of an H-CD/PtÀ TiO 2 heterostructure, where carbon dots (H-CD) were derived from a natural plant source called Rhus Semialata and 1 wt% PtÀ TiO 2 using photodeposition technique. After thorough characterization using various techniques including XPS, XRD, UV-DRS, etc., the nanocomposites as-prepared as well as the pristine materials were examined for their hydrogen generation capabilities using a 450 W XeÀ Hg lamp. Inference from the experimental data showed that 1 wt %-Pt/TiO 2 nanocomposite with 1 % H-CD demonstrated a higher rate of hydrogen production (180.7 mmol h À 1 g À 1 cat ) than 1 wt%-Pt/TiO 2 . In this work, H-CD and Pt play the role of photosensitizer and co-catalyst respectively in enhancing the hydrogen generation of the nanocomposite compared to that of pure anatase TiO 2 under similar conditions.
Development of useful products from toxic or hazardous waste is a unique strategy to overcome their disposal. In this work, we report the valorization of the toxic flowers of Thevetia peruviana (TP) into blue fluorescent nitrogen doped carbon dots (N‐CDs) with ∼6.6 % nitrogen doping from a single source of biomass without using any external dopant. The hydrophilic N‐CDs are biocompatible and show excitation‐dependent emission. Cytotoxity studies revealed the N‐CDs are selectively toxic towards the cancerous cells (DU‐145, MDA MB‐231, HepG2, and B16) but more biocompatible with normal CHO‐K1 and HEK‐293 cells. It has been observed that generation of reactive oxygen species in presence of N‐CDs cause DNA damage and the unrepaired cells undergo apoptosis in G2/M phase. To investigate the toxicity to normal cells, we further carried out in‐vitro and in‐vivo genotoxicity studies to reveal its non‐mitotoxic, non‐clastogenic, and non‐aneugenic properties.
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