Synthesis of coralloid carbon nitride polymers and photocatalytic selective oxidation of benzyl alcohol

Polymeric carbon nitride (C₃N₄) is currently the most potential nonmetallic photocatalyst, but it suffers from low catalytic activity due to rapid electron–hole recombination behavior and low specific surface area. The morphology control of C₃N₄ is one of the effective methods used to achieve higher photocatalytic performance. Here, bulk, lamellar and coralloid C₃N₄ were synthesized using different chemical methods. The as-prepared coralloid C₃N₄ has a higher specific surface area (123.7 m² · g⁻¹) than bulk (5.4 m² · g⁻¹) and lamellar C₃N₄ (2.8 m² · g⁻¹), thus exhibiting a 3.15- and 2.59-fold higher photocatalytic efficiency for the selective oxidation of benzyl alcohol than bulk and lamellar C₃N₄, respectively. Optical characterizations of the photocatalysts suggest that coralloid C₃N₄ can effectively capture electrons and accelerate carrier separation, which is caused by the presence of more nitrogen vacancies. Furthermore, it is demonstrated that superoxide radicals (·O₂ ⁻) and holes (h⁺) play major roles in the photocatalytic selective oxidation of benzyl alcohol using C₃N₄ as a photocatalyst. (paper)