Salt-assisted construction of hydrophilic carbon nitride photocatalysts with abundant water molecular adsorption sites for efficient hydrogen production

Polymer carbon nitride (PCN), as an affordable and easily prepared photocatalyst, has acquired extensive attention for hydrogen production. However, bulk carbon nitride material exhibits poor dispersibility in water due to the relatively inert surface which limits its quantum efficiency in photocatalytic hydrogen production. In this study, a hydrophilic carbon nitride (HCN) is successfully synthesized by a novel salt-assisted heating process. The heightened water adsorption capacity may contribute additional active sites conducive to the photocatalytic hydrogen production reaction. Meanwhile, potassium ion doping and material size reduction greatly enhance the charge transfer and separation ability of HCN. Consequently, HCN exhibits highly efficient photocatalytic activity for hydrogen production, achieving a rate of 392 μmol·h −1 , which is 16 times greater than that of pristine PCN. The simply developed synthetic strategy adopted here provides a novel concept for functionalizing carbon nitride and opening a distinct pathway for the construction of exceptionally efficient photocatalytic systems. • The salt-assisted method is used to synthesize hydrophilic carbon nitride (HCN) materials. • The obtained HCN has more hydrophilic functional groups, which can be well dispersed in water to fabricate a quasi-homogeneous photocatalytic system. • The enhanced water adsorption capacity may provide more active sites for photocatalytic hydrogen production reaction. • The potassium ion doping and material size reduction greatly enhance the charge transfer and separation ability of HCN. • HCN exhibits highly efficient photocatalytic activity for hydrogen production, which is 16 times higher than that of pristine PCN.