“…Moreover, the doped metal ions can promote the electron-hole recombination and suppress the photocatalytic reactivity. Carbon-based materials such as graphite or CNT have been employed as matrix for metal oxide as well as for light absorption-assistant materials (Sharma et al, 2021;Idris et al, 2021;Ibrahim et al, 2020;Isari et al, 2020;Stan et al, 2019;Jung et al, 2018). The carbon materials can absorb light of lower energy and play the role of an electron reservoir in the system, leading to the increased e ciency of photocatalytic reaction.…”