Application of Niobium Enriched Ormosils as Thermally Stable Coatings for Aerospace Aluminium Coatings

The aim of this experimental research is to study the ability of niobium rich sol-gel coatings to withstand thermal stress, while remaining impermeable to corrosive agents for the protection of aerospace alloys. The coating material is developed via polymeric sol-gel synthesis employing 3-(trimethoxysilyl)propylmethacrylate (MAPTMS) and niobium ethoxide precursors as a source of silicon and niobium, respectively. The beneficial effect of niobium inclusion within coating was characterised spectroscopically, calorimetrically and electrochemically. The thermal cycling effects of the coating were studied using microscopic and accelerated test methods. Electrochemical tests showed that corrosion current of the material was 2 orders lower in magnitude than MAPTMS coating. The neutral salt spray test results of thermal stressed samples prove that inclusion of niobium nanoparticles within the silane matrix considerably improves the corrosion resistance performances in salt spray test resulting in better ability to resist thermal shock failure when compared to the MAPTMS coating alone

Synthesis of High-Temperature Stable Anatase TiO2 Photocatalyst

In the absence of a dopant or precursor odification, anatase to rutile transformation in synthetic TiO2 sually ccurs at a temperature of 600 700 °C. Conventionally, metal oxide dopants (e.g., Al2O3 nd SiO2 are used o tune the anatase to rutile transformation. A simple methodology is reported here to extend the anatase utile transformation by employing various concentrations of urea. XRD and Raman spectroscopy were used uring thermal treatment. A significantly higher anatase phase (97%) as been obtained at 800 C with use of a 1:1 Ti(OPr)4 urea composition and 11% anatase composition is etained even after calcining the powder at 900 . On comparison a sample that has been prepared without rea showed that rutile phases started to form at a temperature as low as 600C. The effect of smaller mounts of urea such as 1:0.25 and 1:0.5 Ti(OPr) urea has also been studied and compared. The investigation oncluded that the stoichiometric modification by urea 1:1 Ti(OPr) urea composition is most effective in extending the anatase to rutile phase transformation by 200°C compared to the unmodified sample. In addition, ET analysis carried out on samples calcined at 500°C showed that the addition of urea up to 1:1 Ti(OPr4:urea increased the total pore volume (from 0.108 to 0.224 cm3/g) and average pore diameter (11 to 30 nm)compared to the standard sample. Samples prepared with 1:1 Ti(OPr)4:urea composition calcined at 900 °C how significantly higher photocatalytic activity compared to the standard sample prepared under similarconditions. Kinetic analysis shows a marked increase in the photocatalytic degradation of rhodamine 6G on oing from the standard sample (0.27 min, decoloration in 120 min) to the urea-modified sample (0.73min-1, decoloration in 50 min)

Graphene and its derivatives for air purification: A mini review

Acceleration of industrialization causes an increase in concentration of greenhouse gases (GHGs), particularly CO2, as well as particulate matter in the air. Therefore, it is necessary to develop strategies for the elimination of GHGs. Graphene and its derivatives were reported to be excellent candidates for CO2 adsorption and also for the removal of particulate matter by air filtration. For the fabrication of air filtration membranes, by using graphene/graphene derivatives, they were incorporated with certain polymers such as polyacrylonitrile and made into nanofibrous membranes. Electrospun nanofibrous membranes are characterised by high porosity, small pore size and excellent connectivity, have been found to be a promising candidate for air filtration. The review article focuses on two aspects of air purification, first part discuss the use of graphene/graphene derivatives for CO2 adsorption and the second part discuss the use of graphene based electrospun nanofibrous membranes for particulate matter removal. The factors influencing the efficiency of filtration has been discussed in detail

Polyindole-Derived Nitrogen-Doped Graphene Quantum Dots-Based Electrochemical Sensor for Dopamine Detection

The sensitive monitoring of dopamine levels in the human body is of utmost importance since its abnormal levels can cause a variety of medical and behavioral problems. In this regard, we report the synthesis of nitrogen-doped graphene quantum dots (N-GQDs) from polyindole (PIN) via a facile single-step hydrothermal synthetic strategy that can act as an efficient electrochemical catalyst for the detection of dopamine (DA). The average diameter of N-GQDs was ∼5.2 nm and showed a C/N atomic ratio of ∼2.75%. These N-GQDs exhibit a cyan fluorescence color under irradiation from a 365 nm lamp, while PIN has no characteristic PL. The presence of richly N-doped graphitic lattices in the N-GQDs possibly accounts for the improved catalytic activity of N-GQDs/GCE towards electrocatalytic DA detection. Under optimum conditions, this novel N-GQDs-modified electrode exhibits superior selectivity and sensitivity. Moreover, it could detect as low as 0.15 nM of DA with a linear range of 0.001–1000 µM. In addition, the outstanding sensing attributes of the detector were extended to the real samples as well. Overall, our findings evidence that N-GQDs-based DA electrochemical sensors can be synthesized from PIN precursor and could act as promising EC sensors in medical diagnostic applications

Self-Doped ZnO MicrorodsHigh Temperature Stable Oxygen Deficient Platforms for Solar Photocatalysis

Dopant free, solar active ZnO photocatalysts with oxygen vacancy richness were achieved by a solution processing strategy followed by calcination at various temperatures 300, 500, 700, 800, and 900 °C. All the ZnO nanocrystals possessed defective structures with copious surface oxygen vacancies directed toward notable visible light absorption around λ = 480 nm (band gap = 3.05–3.09 eV). The photocatalytic efficiencies of all ZnO samples were systematically examined under sunlight and UV illumination using methylene blue (MB) as a model system. ZnO calcined at 500 and 700 °C demonstrated microrod morphology with band gap energies of 3.08 and 3.09 eV respectively have shown the highest solar photocatalytic activity revealed the synergistic effect between oxygen vacancy and the rod morphology. ZnO calcined at 500 °C, having maximum surface oxygen vacancy sites degraded MB within 10 min whereas the commercial photocatalyst Degussa-P25 has taken 20 min under solar illumination