J. Am. Chem. Soc. 2019, 141, 2508−2515

Yuting Xiao, Honggang Fu*, Molecule Self-Assembly Synthesis of Porous Few-Layer Carbon Nitride for Highly Efficient Photoredox Catalysis (J. Am. Chem. Soc. 2019, 141, 2508−2515.)

Polymeric carbon nitride (C₃N₄) has emerged as the most promising candidate for metal-free photocatalysts but is plagued by low activity due to the poor quantum efficiency and low specific surface area. Exfoliation of bulk crystals into ultrathin nanosheets has proven to be an effective and widely used strategy for enabling high photocatalytic performances; however, this process is complicated, time-consuming, and costly. Herein, we introduce a simple and low-cost bottom-up

method for production of porous few-layer C₃N₄, obtained by a sequential molecule self-assembly, alcohol molecules intercalation, thermal-induced exfoliation, and polycondensation process. The resultant products have a high quality, a specific surface area of up to 164.2 m^-2 g ⁻¹, a high electrical conductivity, and an ultrathin morphology with well-distributed primarily 2 to 15 nm-width pores. We show that a remarkably increased photocatalytic hydrogen evolution activity can be obtained, which is a 26-fold higher than that of the bulk C₃N₄, reaching an overall apparent quantum efficiency (AQE) of approximately 9.8%. We further show that unprecedented activity and selectivity for the oxidative coupling of amines to imines can be achieved under mild conditions, which is among the best photocatalysts reported so far. The unprecedented performance is due to the synergic advantages of enlarged surface area, increased access to reaction sites, facilitated diffusion of reactants and products, and remarkably improved charge carrier transfer and separation. In addition, this work also paves the way for construction of few-layer C₃N₄ materials with excellent optical and electrical properties, which can be anticipated for versatile applications in the fields of photocatalysis, photoelectrocatalysis, and optoelectronic devices.