Fabrication of a novel ZnIn2S4/g-C3N4/graphene ternary nanocomposite with enhanced charge separation for efficient photocatalytic H2 evolution under solar light illumination.

Design and synthesis of efficient photocatalyst systems for a large volume of hydrogen (H2) evolution under solar light is still a great challenge. To obtain high photocatalytic activity, graphene-based semiconductor photocatalysts are gaining heightened attention in the field of green and sustainable fuel production due to their good electronic properties, high surface area and chemical stability. Herein, we demonstrate an efficient, novel and smart architecture of a graphene-based ZnIn2S4/g-C3N4 nanojunction by a simple hydrothermal process for H2 generation. In the present study, graphene (G) is chosen as the electron mediator and ZnIn2S4 (ZIS) and g-C3N4 (CN) are chosen as two different semiconductor photocatalysts to construct a smart architecture for the ternary photocatalytic system. Different characterization techniques such as XRD, TGA, FT-IR, SEM, TEM, HR-TEM, XPS, BET, and UV-vis DRS were employed to ensure the successful integration of graphene, ZnIn2S4, and g-C3N4 in the nanocomposite. As a result, high and efficient H2 evolution (477 µmol h-1 g-1) is attained for the graphene-based ZnIn2S4/g-C3N4 nanocomposite. Transient photocurrent experiments, ESR, PL, and time-resolved PL studies suggested that the intimate ternary nanojunction effectively promotes fast charge transfer and thereby enhances photocatalytic H2 evolution.

Microwave-assisted synthesis of ZnAl-LDH/g-C3N4 composite for degradation of antibiotic ciprofloxacin under visible-light illumination.

Ciprofloxacin (CIP) is a fluoroquinolone family antibiotic pollutant. CIP existence in water environment has been rising very fast in day-to-day life and subsequently, it gives enormous health issues for humans because of its potent biological activity. To encounter this, current researchers are focusing on the development of highly efficient visible light semiconductor nanocomposites with potential photocatalytic activity. In the present work, we have successfully synthesized highly efficient zinc-aluminum layered double hydroxides with graphitic carbon nitride (ZALDH/CN) composites via a simple microwave irradiation method first time for the degradation of CIP under visible light. The fabricated materials are subsequently characterized by various spectroscopic techniques. UV-Vis DRS, TRFL, XRD, FT-IR, BET, FE-SEM, TEM, and XPS for optical, crystal structure, morphological, and elemental analysis. The main reactive intermediates which are formed during the photocatalytic degradation process were analyzed by LC-MS analysis. It is worth to note that, the optimized ZALDH/CN-10 composite showed the highest photo-degradation rate constant of 1.22 × 10-2 min-1 with 84.10% degradation is higher than bare CN and ZALDH photocatalysts. Based on the electron-hole pair trapping experiment results, possible CIP photo-degradation mechanism was also explained in the present study. With all results, this work demonstrates the ZALDH/CN composite materials showed a high synergistic effect with more specific surface area. Highest specific surface area leads to enhanced visible light adsorption capacity. Subsequently improved number of catalytically active sites. Furthermore, as compared with pure materials, composites of ZALDH/CN are having low electron-hole pair recombination. Consequently, the composites ZALDH/CN showed superior photocatalytic activity for antibiotic pollutant CIP degradation under visible-light illumination.

Mechanistic Investigations of Growth of Anisotropic Nanostructures in Reverse Micelles.

Tailoring the characteristics of anisotropic nanostructures like size, morphology, aspect ratio, and size dispersity is of extreme importance due to the unique and tunable properties including catalytic, optical, photocatalytic, magnetic, photochemical, electrochemical, photoelectrochemical, and several other physical properties. The reverse microemulsion (RM) method offers a useful soft-template and low-temperature procedure that, by variation of experimental conditions and nature of reagents, has proved to be extremely versatile in synthesis of nanostructures with tailored properties. Although many reports of synthesis of nanostructures by the RM method exist in the literature, most of the research studies carried out still follow the "hit and trial" method where the synthesis conditions, reagents, and other factors are varied and the resulting characteristics of the obtained nanostructures are justified on the basis of existing physical chemistry principles. Mechanistic investigations are scarce to generate a set of empirical rules that would aid in preplanning the RM-based synthesis of nanostructures with desired characteristics as well as make the process viable on an industrial scale. A consolidation of such research data available in the literature is essential for providing future directions in the field. In this perspective, we analyze the literature reports that have investigated the mechanistic aspects of growth of anisotropic nanostructures using the RM method and distil the essence of the present understanding at the nanoscale timescale using techniques like FCS and ultrafast spectroscopy in addition to routine techniques like DLS, fluorescence, TEM, etc.

High potential and robust ternary LaFeO3/CdS/carbon quantum dots nanocomposite for photocatalytic H2 evolution under sunlight illumination.

Exploitation of the novel, robust, and advanced photocatalytic systems with high efficiency is the present demand for clean, green, and sustainable energy production. Carbon quantum dots (CQDs) have attracted tremendous interest in efficient H2 evolution from photocatalysis due to its remarkable visible-light harvesting and electron transport properties. Here, for the first time, a smart ternary nanocomposite comprises encapsulated CQDs with LaFeO3 spherical nanoparticles and CdS nanorods is synthesized by a simple hydrothermal procedure for the efficient photocatalytic H2 evolution under sunlight illumination. PXRD, FT-IR, FE-SEM, TEM, and XPS studies are performed to ensure the successful fabrication of ternary LaFeO3/CdS/CQD nanocomposite. The efficient H2 evolution rate (HER) of 25,302 µmol h-1 gcat-1 is achieved for LaFeO3/CdS/CQD nanocomposite, which is 602.4, 2.6, 29.8, 2.0 and 1.1 times higher than that of pristine LaFeO3, pristine CdS, and composites such as LaFeO3/CdS, LaFeO3/CQD, and CdS/CQD. Photocurrent and lifetime PL studies reveal, encapsulation of CQDs with the LaFeO3/CdS heterojunction can facilitate easy and efficient separation of photo-generated excitons. Altogether the fabrication of CQDs provides an ideal avenue for the development of high potential advanced photocatalytic systems for sustainable H2 production with remarkable efficiencies.