Secondary-calcination synthesis of nitrogen-deficient polymeric carbon nitride for enhancement of photocatalytic performance: Research on key influential factors

Secondary calcination is an extensively used way to enhance photocatalytic performance of polymeric carbon nitride (PCN), but the influence of raw materials has not been researched, and systematic research on factors affecting photocatalytic activity of secondary-calcination synthesized PCN (RCN) is still rare. Herein, melamine, melamine-cyanuric acid hydrogen bonding complex, and urea were used as raw materials, respectively, to synthesize RCN (marked as M-RCN, MC-RCN, and U-RCN), with their photocatalytic hydrogen evolution and contaminant degradation activity following the order, M-RCN < MC-RCN < U-RCN. Gradual decrease of mean thickness of nanosheets, leading to enhancement of photoinduced charge separation, plays a main role for the photoactivity improvement, and surface area and interfacial affinity changes are minor factors. The surface reaction kinetics is also a probable factor. This work clarifies significant influential factors of photoactivity of RCN and may guide development of efficient PCN-based photocatalysts.