Mild synthesis of {001} facet predominated Bi2O2CO3 clusters with outstanding simulated sunlight photocatalytic activities

Abstract

Bi₂O₂CO₃ clusters made up of ultrathin nanosheets with predominated {001} facets were facilely synthesized via a template-free hydrothermal strategy at a mild temperature of 60 °C. Na₂CO₃ dosage and reaction temperature are confirmed to be key parameters to obtain the hydrolysis product of (Bi₂O₂)²⁺ from bismuth nitrate and provide a suitable microenvironment for the assembly of nanosheets. The sample exhibits obviously improved photocatalytic activity for the degradation and mineralization of Rhodamine B compared with thicker Bi₂O₂CO₃ plates of less exposed {001} planes, with the reaction rate constant k enhanced by 3.4 fold. Photoluminescence and electrochemical impedance results confirm that the {001} facets are reactive and favorable for the separation and migration of photogenerated carriers, which primarily account for the superior photocatalytic behavior of the Bi₂O₂CO₃ clusters. In addition, the enhanced specific surface area should also contribute to the improved photocatalytic activity. Based on the band edge positions of Bi₂O₂CO₃ and the redox potentials of detected oxidative species, a possible migration mechanism of photogenerated e⁻/h⁺ pairs on the surface of Bi₂O₂CO₃ is proposed. This work provides some new insight into the rational design and synthesis of facet-dependent semiconductor photocatalyst under mild conditions.