No abstract

Molybdenum (Mo) impregnated g-C3N4 (Mo-CN) nanotubes are fabricated via a thermal/hydrothermal process to augment photoelectrochemical properties during solar-driven water-splitting (SDWS) reactions. Graphitic-C3N4 is an attractive material for photocatalysis because of its suitable band energy, high thermal and chemical stability. The FE-SEM and HR-TEM comprehend the nanotube-like morphology of Mo-CN. The spectroscopic characterization revealed bandgap energy of 2.63 eV with high visible-light activity. The x-ray diffraction of pristine g-C3N4 and Mo-CN nanotubes discloses the formation of triazine-based nanocrystalline g-C3N4, which remains stable during hydrothermal impregnation of Mo. Furthermore, Mo-CN nanotubes possess high sp2-hybridized nitrogen content, and metallic/oxidized Mo nanoparticles (in a ratio of 1:2) are impregnated into g-C3N4. The XPS analysis confirms C, N, and Mo for known atomic and oxidation states in Mo-CN. Furthermore, high photocurrent efficiency (~ 5.5 mA/cm2) is observed from 5%-Mo-CN nanotubes. That displays efficient SDWS by 5%-Mo-CN nanotubes than other counterparts. Impedance spectroscopy illustrated the lowest charge transfer resistance (Rct) of 5%-Mo-CN nanotubes, which further confirms the fast electron transfer kinetics and efficient charge separation resulting in high photocurrent generation. Hence, 5%Mo-CN composite nanotubes can serve as a potential photocatalytic material for viable solar-driven water splitting.

No abstract

Metal matrix nanocomposites are advanced materials developed using ceramic nanoreinforcements and nanocrystalline metal matrices. These composites have outstanding properties and high potential for large number of functional and structural applications. In this work, nanocrystalline aluminium and Al-Al2O3nanocomposites were synthesised using mechanical alloying and consolidated through spark plasma sintering technique. Scanning electron microscopy, X-ray diffraction, and mapping were used to characterize the powders and sintered samples. Density and hardness of sintered samples were measured using densimeter and hardness tester, respectively. It was found that milling of pure aluminium for 24 h reduced its crystallite size to less than 100 nm. For Al-Al2O3nanocomposites, milling for 24 h decreased the crystallite size of the aluminium phase and resulted in uniform dispersion of the reinforcement. Sintering of the synthesised powders led to grain growth. Al2O3contributed to growth inhibition when samples were sintered for 20 minutes and improved the hardness but reduced densification. The Al-10 vol.%  Al2O3nanocomposite had the highest Vickers hardness value of 1460 MPa.