Annealed Polycarbazole/Tin Oxide/Graphene Oxide Ternary Nano Composite: A Highly Efficient Photocatalyst for the Photodegradation of Congo Red Dye under UV and Natural Daylight Irradiations

PCz (polycarbazole)/SnO2/graphene oxide (GO) ternary nanocomposite, PTG, was successfully synthesized via facile chemical route. The synthesized nanocomposite was characterized in detail by using various advanced techniques. The effects of annealing on the micro structure, phase composition, and photocatalytic performance of PTG correlated with photoluminescence (PL) and electrochemical impedance (EIS) spectrum were investigated. The UV-DRS spectra disclose that the absorption is red shifted owing to the effect of annealing and the band gap of annealed PTG were decreased from 3.60 eV to 3.47 eV. The surface area of annealed PTG is 36.50 m(2)/g which is 3.9 times higher than the unannealed (9.30 m(2)/g). The annealed PTG shows flake like morphology accompanied by low degree of aggregation and demonstrated superior photodegradation efficiency against congo red (CR) dye under UV (95.9 %) and natural day light (98.4 %) irradiations. The photodegradation rate (k) of annealed PTG is 0.06584 which is two times larger than that of unannealed under the identical conditions. The radical trapping experiment demonstrated that the holes (h(+)) and superoxide (*O-2(-)) played a dominant role in the photodegradation of CR dye. Furthermore, the possible mechanism is established by identifying the radicals involved in photodegradation. In addition, the material demonstrated excellent stability after five consecutive cycles with only a 4-6 % loss in photo catalytic efficiency. Total organic carbon analysis shows the removal percentage of 64.6 % (UV) and 76.9 % (natural daylight) towards CR dye. The work presented here provides new platform which throw light into the practical applications of the ternary based nano composite in the field of photocatalysis.

Automated summary

PCz/SnO2/GO ternary nanocomposite PTG was successfully synthesized and characterized using advanced techniques. It was found that annealing enhanced the photocatalytic performance and photodegradation efficiency of PTG, as confirmed by FTIR and spectroscopic analysis.