LAUSR

Various multi-wall carbon nanotube (MWCNT)/titanium dioxide nanocomposites were synthesized using a low-temperature sol–gel method and a simple evaporation and drying process. Various techniques such as X-ray diffraction, energy-dispersive X-ray analysis, UV–visible diffuse reflectance spectroscopy, and scanning electron microscopy were used to confirm the structures of the newly synthesized nanocomposites. The photocatalytic activity of the new nanocomposites was investigated by using them as catalysts for the degradation of Bismarck brown R dye. The maximum rate of BBR photodegradation was achieved with a composite with a $$\hbox {MWCNT}/\hbox {TiO}_{2} $$MWCNT/TiO2 ratio of 0.5% (w/w). The photocatalytic activity of $$ \hbox {TiO}_{2} $$TiO2 was improved in the presence of the new MWCNT nanocomposite. The synthesized nanocomposite shows an obvious red shift compared to $$ \hbox {TiO}_{2} $$TiO2. The band gap of $$ \hbox {TiO}_{2} $$TiO2 was reduced from 3.25 to 2.8 eV in the presence of MWCNTs (0.5 wt%). Evidently, the recombination of photogenerated electron–hole pairs could be retarded in the presence of a MWCNT/$$\hbox {TiO}_{2} $$TiO2 nanocomposite. Moreover, MWCNTs can control $$\hbox {TiO}_{2} $$TiO2 particles’ morphology within the MWCNT/$$\hbox {TiO}_{2} $$TiO2 nanocomposite by acting as a dispersing support.