Which Type of Carbon Nitride More Suits Photocatalysis: Amorphous or Crystalline?

Abstract Graphitic carbon nitride (g‐C 3 N 4 ) has witnessed tremendous research interest due to its narrow bandgap, intrinsic 2D structure, and abundant raw materials. Although g‐C 3 N 4 has some shortcomings such as low specific surface area, poor conductivity and rapid charge carries recombination, various modification methods are constantly emerging to enhance its potential application value in photocatalysis. Increasing the crystallinity of g‐C 3 N 4 is an effective strategy to improve the in‐plane charge separation efficiency. However, it is also reported that amorphous g‐C 3 N 4 possesses a higher adsorption and activation ability over reactants due to its richer surface functional groups than crystalline g‐C 3 N 4 . Which type of g‐C 3 N 4 more suits photocatalysis, and which modification method is more suitable for boosting the activity of two types of g‐C 3 N 4 , respectively? Based on these issues, the recent advances in the preparation and properties of amorphous and crystalline g‐C 3 N 4 are summarized, and their performance improvement strategies are overviewed thoroughly. Upon systematic comparison and analysis, which modification strategy is more suitable for the two types of g‐C 3 N 4 , respectively, is proposed. Their applications are also summed up especially in environment remediation and energy conversation. Finally, the ongoing opportunities and future challenges for amorphous and crystalline g‐C 3 N 4 in the photocatalysis territory are taken for consideration.