RESUMO
Semiconductor films are crucial in photocatalysis applications, yet their controlled production remains challenging. Previous studies have mainly focused on deposition processes, heating rates, and doping of semiconductor oxides. In this paper, we introduce a novel method for fabricating tenorite (CuO) semiconductor films with varying precursor concentrations (0.01, 0.02, 0.04, 0.06, and 0.1 g/ml) using a dip-coating technique. We explore the impact of contact angles, 3D surface topography, and film thickness on photoactivation properties, areas with limited previous research focus. The results demonstrate that higher-concentration tenorite films (0.1 g/ml) exhibit rougher surfaces (77.3 nm), increased hydrophobicity (65.61°), improved light-harvesting ability, enhanced charge separation, and higher active oxygen output. The crystal sizes were within the range of 7.3-44.1 nm. Wettability tests show a 21.47% improvement in the 0.1 g/ml film surface under indirect sunlight compared to darkness. Transmittance rates in the 600 nm range were from 0.02 to 90.94%. The direct optical band gaps were 1.21-2.74 eV, while the indirect band gaps remained unaffected (0.9-1.11 eV). Surface morphology analysis reveals an increased presence of grains with higher concentrations. Regarding photocatalysis's impact on film morphology and copper content, SEM images reveal minimal changes in film structure, while copper content remains stable with slight variations. This suggests strong adhesion of tenorite to the film after photocatalysis. Tenorite thin films display exceptional photocatalytic efficiency, making them suitable for practical applications.
RESUMO
Chitosan (CS) is one of the most abundant biopolymers in nature with superior properties such as biocompatibility, biodegradability, lack of toxicity, antimicrobial activity, acceleration of wound healing, and stimulation of the immune system. In this study, chitosan was extracted from the exoskeletons of beetles (Pimelia payraudi latreille) and then used for the biosynthesis of highly pure MgO NPs and ZnO NPs by a facile greener route. The extracted chitosan exhibited excellent physicochemical properties, including high extraction yield (39%), high degree of deacetylation (90%), low ash content (1%), high fat-binding capacity (366%), and unusual crystallinity index (51%). The MgO NPs and ZnO NPs exhibited a spherical morphology with crystallite sizes of 17 nm and 29 nm, particle sizes of about 20-70 nm and 30-60 nm, and band gap energies of 4.43 and 3.34 eV, respectively. Antibacterial assays showed that the extracted chitosan exhibited high antibacterial activity against Gram-positive and -negative bacteria, while ZnO NPs showed much stronger antibacterial activity against Gram-positive bacteria than against Gram-negative bacteria. For MgO NPs, the antibacterial activity against Gram-positive bacteria was lower than against Gram-negative bacteria. The results suggest that the synthesized MgO NPs and ZnO NPs are excellent antibacterial agents for therapeutic applications.
