Graphene-wrapped Bi2O2CO3 core–shell structures with enhanced quantum efficiency profit from an ultrafast electron transfer process

Graphene (GR)-wrapped rose-like Bi2O2CO3 (WBGR) core–shell structures are synthesized to maximize their contact area and quantum efficiency. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results indicate that C–Bi bonds are formed, leading to a close chemical interfacial connection between Bi2O2CO3 and GR, as well as a concurrent red shift at the absorption edge (λ = 430 nm). More importantly, an ultrafast electron transfer process (≤800 ps) from Bi2O2CO3 to GR via the C–Bi bonds is detected in WBGR, inhibiting recombination of the charge carriers and contributing to high photocatalytic activity for carbamazepine (CBZ) degradation. As a result, the highest apparent quantum efficiency Φ (2.62%) and charge separation yield (9.4 × 1017 spin per g), as well as quenching factor (4.51), are achieved by WBGR. Finally, radical control experiments demonstrate that ˙O2− radicals, ˙OH radicals and holes participate in the photocatalytic process. Consequently, WBGR displays an apparent rate constant (k) of 2.81 × 10−4 s−1, which is 8.67 and 4.15-fold higher than that of Bi2O2CO3 and graphene–Bi2O2CO3 (BGR), respectively.