The XPS analysis of the TNFG-2 composite after photocatalytic degradation of MO showed that the ACAO/ACAC ratio further reduced to 0.25. This reveals further reduction of GO in the presence of UV light [54,15]. However, the composite irradiated by UV light for 6 h after thermal reduction, did not show any further reduction of GO, compared to the used composite (Fig. 5E). These results are consistent with the previous reports of Wong et al. [52].