The anticipated course of the direct C(sp 2 )-H trifluoromethylation of arenes with Togni-I reagent, utilizing Cu@f-gC3N4 photocatalyst was envisioned to follow a radical mechanism. To probe this radical pathway, a radical quenching experiment (S2.8A, ESI) was conducted by subjecting nitrobenzene (1a) to Togni-I (2a) reagent under the optimized reaction conditions in the presence of (2,2,6,6-tetramethylpiperidine-1-yl)oxyl (TEMPO, 3.0 equiv.). The introduction of TEMPO into the reaction mixture resulted in a pronounced inhibition of the trifluoromethylation process, ultimately preventing the detection of the trifluoromethylated product. Similarly, the replacement of TEMPO by butylated hydroxytoluene (BHT, 2.0 equiv.) as a spin trap yielded no observable product. Furthermore, when the model reaction was conducted with suitable ligands (4-bromobenzenethiol and butan-1amine), which can coordinate with the active site of Cu in the photocatalyst, the desired product 3a was achieved in 19% (p/m=2:1) and 26% (p/m=2:1) yields respectively (S2.8B, ESI). This experimental validation showcased the significance of the Cu-active site in the photocatalyst's efficacy. Additionally, to ascertain whether the rate-determining step was involved with the breaking of the C-H bond, a kinetic isotope effect (KIE) analysis was undertaken (S2.8C, ESI) and strongly implied that the cleavage of the C-H bond was indeed the pivotal rate-limiting step (KH/KD = 1.85). Moreover, to elucidate the metal-substrate interaction in a ƞ 2 fashion, wherein the Cu(I) atom forms a direct connection with the arene substrates through an aromatic Cortho-Cmeta bond of the ring , we employed the para-blocked substrate (product 3a) under the optimized reaction conditions (S2.8D, ESI). Our observations revealed the absence of any aromatic C-H bond functionalized product, substantiating the hypothesis of η 2 -bonding between the Cu-metal and the ortho/meta carbon of the aromatic substrate. This interaction effectively blocks other C-H bonds from undergoing functionalization.