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Novel nanostructures of h-BN and e-Fe2O3 grafted h-BN (h-BN/e-Fe2O3) have been synthesized by solvothermal method. The prepared h-BN/e-Fe2O3 nanostructures are highly reproducible. XRD analysis confirmed the phase and crystal structure of synthesized h-BN and h-BN/e-Fe2O3 nanostructures. The sheet like morphology of the nanostructured h-BN and h-BN/e-Fe2O3 are confirmed by SEM, TEM and HRTEM analyses. Moreover, the uniform distributions of e-Fe2O3 on the surface of h-BN nanosheets are confirmed by SEM and TEM images. FT-IR and Raman studies are used to identify the functional groups and structure of h-BN and h-BN/e-Fe2O3 nanostructures. The optical absorption spectra show a clear red shift in the h-BN/e-Fe2O3 nanostructure compared to pure h-BN nanosheets which shows the electronic band structure modification in BN caused by grafting of e-Fe2O3 nanoparticles onto the surface of h-BN. The chemical composition of prepared h-BN/e-Fe2O3 heterostructure is analyzed by XPS. The photo oxidative performance of pure h-BN and h-BN/e-Fe2O3 nanostructure has been studied for oxidative decomposition of formic acid under visible light irradiation. The h-BN/e-Fe2O3 nanostructure showed relatively high photo oxidative performance compared to pure h-BN.

Water dispersible graphene layer are the excellent nano materials used for wide range of electronic applications. High quality graphene was synthesized by an eco-friendly, easy and cost effective electrochemical exfoliation method. In this work, graphite rod was used both as an anode and cathode for the production of graphene. Potassium sulphate (K2SO4) was used as an intercalating agent. Electrochemically exfoliated graphene (EEG) was coated on glassy carbon electrode (GCE) and evaluated towards the electrochemical oxidation of vanillin and L-phenylalanine. The fabricated electrode was able to detect vanillin and L-Phenylalanine as low as 0.2 μM with signal to noise ratio of 3. A significant increase in the current was observed for the graphene coated electrode for both vanillin and L-phenylalanine when compared to bare Glassy electrode. The finding clearly demonstrated the higher detection capability, selectivity and reproducibility of EEG.

N-doped titania nano sheets and N-doped titania/tungsten dioxide nano rods were synthesized by two step hydrothermal method. The composition, structural, functional, morphological and optical properties of the as synthesized N-TiO₂/WS₂ hybrids were characterized by XRD, UV-DRS, PL, FE-SEM with EDAX, TEM, FT-IR and Raman spectroscopy. Surface area and thermal stability of the catalysts were analyzed by BET and TG/DTA techniques. The photocatalytic activity of the heterojunction catalyst was evaluated towards the decomposition of a harmful dye namely congo red in an aqueous solution under visible light irradiation. The results show superior photocatalytic activity for N-TiO₂/WS₂ nanocomposite. This unusual photocatalytic activity is attributed to the synergistic effect between WS₂ and N-TiO₂.

A facile hydrothermal method was adopted for the synthesis of bare TiO₂ and titania nanotubes (TNT). In an effort to increase the efficacy of the existing photocatalyst, different weight percentage (0.2, 0.4, 0.6, 0.8 and 1.0%) of praseodymium were deftly doped on to the synthesized titania scaffolds. The physicochemical characteristics of the architectured photocatalyst were thoroughly elucidated by various sophisticated techniques. The doping of Pr₂O₃ (Pr) on to titania nanotubes (TNT) resulted into a significant bathochromic/hyperchromic shift in the optical absorption edge (towards the visible region) as perceived from the DRS-UV spectra. The XRD and TEM analysis showed average crystallite size of the synthesised photocatalyst to be as small as 4-7 nm with well-formed nanotube framework. Photoluminescence spectra of Pr doped TNT catalyst clearly exhibited greater suppression of photogenerated electron-hole pair as compared to the undoped counterparts. The photocatalytic activity of the synthesized catalysts was evaluated towards the degradation of organic pollutants namely Rhodamine B (90%) and Crystal violet (93%) in the presence of solar light and its activity and durability was compared to that of commercial TiO₂ (Degussa P25). The observed enhanced photocatalytic activity of TNT and Pr-TNT can be unambiguously attributed to the inhibition of recombination of the electron-hole pairs due to doping of Pr into TNT. Among catalysts synthesized, 0.4 wt.% of Pr on to TNT yielded the highest photocatalytic activity under visible light irradiation.

Titania by sol gel and Ni-Ru titania catalysts by wet impregnation methods were prepared and characterized by XRD, UV-DRS, BET and TEM techniques. Catalytic activities of the photocatalysts were evaluated towards the degradation of three widely used neonicotinoids type insecticides namely acetamiprid, imidacloprid and thiamethoxam under UV, Visible and solar irradiations. The reaction parameters such as initial concentration of the insecticide, weight of the catalyst and pH of the system were found to influence the reaction rate. The results indicated that the metal impregnated catalysts were found to be more active than pure TiO₂.Ni/TiO₂ or Ru/TiO₂ catalysts degraded all the insecticides completely even under visible irradiation. The observed visible activity of the catalysts was attributed to their lower band gap values. HPLC and TOC analyses revealed that mineralisation of the insecticides occurred through dearomatization by multiple hydroxylation and oxidation. The degradation pathway and the kinetics were also discussed in detail.

The preparation of semiconductor Quantum Dots (QDs) with controllable size, shape and doping remains a biggest challenge, especially the size below 10 nm. To date, only scarce attempts have been made on the synthesis of ZnSe QDs using biomolecule-assisted hydrothermal approach. Hence the current research work examines the influence of some amino acids namely L-cysteine, methionine and tyrosine as stabilizing agents in the synthesis of ZnSe nanocrystals. The ZnSe QDs exhibited strong absorption and photoluminescence properties in the region from 200-600 nm. Spectroscopic and structural properties of the as-synthesized biomolecule-capped ZnSe QDs were characterized by UV-vis absorption spectrophotometer, FT-IR, fluorescence spectrophotometer, X-ray diffractometer, Scanning Electron Microscope and EDX analysis. The stabilizing agents have played a crucial role in preparing ZnSe QDs and in determining the photoluminescence properties. The luminescence intensity was enhanced significantly when amino-acid-capped ZnSe QDs were illuminated by UV light compared to visible light. The as-synthesised ZnSe QDs were capable of effectively degrading an organic azo dye Azophlexin, under direct sunlight irradiation and exhibited good stability during photocatalytic experiments which can be attributed to the small size of amino acid capped ZnSe. The degradation mechanism is discussed. The absorbance and FT-IR measurements confirmed the biocompatibility and water-solubility of the pure ZnSe and capped ZnSe QDs.

Herein, we report the synthesis of nitrogen and sulphur co-doped TiO2/rGO nano composites (NST/x%-rGO, x = 2.5, 5, 7.5 & 10%) by facile single step hydrothermal method. The structural and morphological analyses of the synthesized composites were made by XRD, IR, XPS, SEM and TEM, while optical properties were studied by Raman and DRS-UV spectrophotometric techniques. Charge separation efficiency and the extent of recombination were investigated by EIS and photoluminescence (PL) studies. Photodegradation efficiency was evaluated by the de-colorization of congo red (CR), methylene blue (MB) and reactive orange 16 (RO16) dyes. For comparison purpose, TiO2/rGO (GT) and nitrogen, sulphur co-doped TiO2 (NST) were also synthesized, characterized and their photocatalytic activities were evaluated and compared. NST/5%-rGO exhibited the highest photocatalytic activity towards the degradation of all the three dyes under visible light. Improved optical absorption property and increased life time of the photogenerated charge carriers have been observed. Trapping experiments with different quenchers suggested that superoxide radicals (O2 −) were highly responsible for the degradation process compared to other species such as hydroxyl radicals (OH ) and photogenerated holes (h+).

Textile industries produce large quantities of waste water which is notoriously known to contain strong colour, suspended solids and COD. Although several treatment processes, such as filtration, coagulation, oxidation, ozonation, reverse osmosis, etc., have been practiced for many decades, they all have inherent limitations. They transfer the harmful pollutants from one phase to another and do not address detoxification. Semiconductor photocatalysis is a promising technique for photodegradation of hazardous chemicals found in waste waters. Among various semiconductors, TiO2 has been studied widely. However, the main drawbacks associated with TiO2 are (i) large band gap (Eg > 3.2 eV) (only UV active) and (ii) recombination of excitons. Dye sensitisation, coupling of semiconductors, and transitional metal doping are some of the methods reported to shift its optical response to visible region. Herein, nanoparticles of different noble metals such as Ag, Au and Pt were deposited on synthesised TiO2, characterized by XRD, TEM, FT-IR, BET, UV-Vis and AAS and were subjected to the degradation of some textile dyes namely Tartrazine (TAZ), Reactive Yellow-17 (RY-17) and Reactive Black-5 (RB-5) under both UV and visible irradiations. The reaction conditions such as catalyst concentration, dye concentration, pH, irradiation time, light intensity, and additives were optimized for complete decolourisation and discussed.

MTiO₃ (M = Sr, Ca, Ba and Pb) catalysts were synthesized by polymeric precursor method and characterized by using various instrumental techniques such as X-ray diffraction (XRD), UV-diffuse reflectance spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). TiO₂ were also synthesized by sol-gel method and used for the optimization of reaction parameters such as catalyst weight, dye concentration and pH in the photocatalytic degradation of reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) under UV irradiation. MTiO₃ (M = Sr, Ca, Ba and Pb) catalysts were evaluated towards the photocatalytic decolourization of RB 198, RB 5 and RY 145 under optimized reaction conditions. Among the different metal titanates, strontium titanate showed the highest decolourization (≈90%) of all the three reactive dyes under UV irradiation at 120 minutes and also found to be active under visible irradiation as it decolourises the dyes in about 450 minutes. The degradation rate of strontium titanate was monitored by TOC analyzer. Kinetic studies of the photocatalytic degradation of reactive dyes confirmed that the reaction followed the pseudo first order kinetics.

Jatropha oil was cracked over micoporous catalysts, such as HY, HZSM-5, and HMordenite, at the optimized conditions obtained over Hβ towards cracking of jatropha oil. The synthesized catalysts were characterized by X-ray diffraction, Brunauer-Emmett-Teller surface area analyzer, inductively coupled plasma, and temperature programmed desorption techniques. Among the microporous materials, HZSM-5 catalyst was found to be the best in terms of conversion (62%), selectivity towards green gasoline (50%), and less coke formation (0.8%) in the cracking of jatropha oil. Cracking of other oils, such as castor, neem, and pongamia, under the optimized conditions resulted in 82% conversion of castor oil; however, higher selectivity towards green gasoline (49%) was obtained in the cracking of pongamia oil.

The present study reports the synthesis; characterization by X-ray diffraction, Brunauer, Emmett and Teller surface area analyzer, inductively coupled plasma, and temperature programmed desorption techniques of Hβ catalyst; and its catalytic cracking activity towards jatropha oil using a fixed bed flow reactor. The catalytic reaction parameters, such as influence of temperature (400–500°C), weight hourly space velocity (3.8–6.2 h−1), and time of reaction (1–4 h) on percentage conversion of jatropha oil and percentage yield of bio liquid products were studied and optimized over Hβ. Under the optimized conditions, Hβ showed 48% conversion and 30, 45, and 25% selectivities toward green gasoline, green kerosene, and green diesel, respectively.