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

Abstract

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.