Fabrication of a Novel Silica–Alumina-Based Photocatalyst Incorporating Carbon Nanotubes and Nanofiber Nanostructures Using an Unconventional Technique for Light-Driven Water Purification

The advancement of optical materials has garnered significant interest from the global scientific community in the pursuit of efficient photocatalysts for the purification of water using light. This challenge, which cannot be addressed using traditional methods, is tackled in the present study utilizing unconventional approaches. This study presents the fabrication of an effective photocatalyst using an unconventional approach that employs explosive reactions. This method successfully produces 3D nanostructures composed of carbon nanotubes (CNTs), carbon nanofibers (CNFs), and silica–alumina nanoparticles at temperatures below 270 °C. Gold-supported silica–alumina–CNT–CNF nanostructures were synthesized and characterized using XRD, TEM, SEM, and EDX, in addition to mapping images. To study and determine the photoactivity of these produced nanostructures, two well-known photocatalysts—titanium dioxide and zinc oxide—were synthesized at the nanoscale for comparison. The results showed that the presence of CNTs and CNFs significantly reduced the band gap energy from 5.5 eV to 1.65 eV and 3.65 eV, respectively, after modifying the silica–alumina structure. In addition, complete degradation of green dye was achieved after 35 min of light exposure using the modified silica–alumina structure. Additionally, the surface properties of the modified silica–alumina had a positive role in accelerating the photocatalytic decomposition of the green dye NGB. A kinetic study confirmed that the modified silica–alumina functions as a promising additive for optical applications, accelerating the photocatalytic degradation of NGB to a rate three times faster than that of the prepared titanium dioxide and six times that of the prepared zinc oxide.