Enhancement of g-C3N4 Photocatalysis by Selectively Anchoring Metal Cocatalysts with a Strong Metal–Support Interaction

Cocatalysts (Pt or Pd) can significantly enhance the activity of photocatalysts. However, the electron transfer between cocatalysts and different kinds of functional groups have not been thoroughly studied. Here, a strategy of selectively anchoring cocatalysts (Pt or Pd nanoparticles (NPs)) on oxygen-doped carbon nitride (O-CN) was developed to optimize the electron transfer and enhance the photocatalytic activity. The oxygen functional groups are found to be beneficial to the loading of cocatalysts on the surface of O-CN. The adsorption energy (Eads) of Pd NPs on the N–C–O site is more negative than that on the C–O–C site, resulting in a favorable anchoring of Pd NPs on N–C–O, while the Eads of Pt NPs is lower on C–O–C than on N–C–O, leading to a preferential deposition of Pt on C–O–C. The O atom of N–C–O species, which possesses a lower value of isolated state than that of C–O–C species, shows a weaker electron-withdrawal property. So that the electrons can quickly transfer from O-CN to Pd than to Pt, leading to a higher hydrogen generation activity of O-CN/Pd than those of O-CN/Pt by photocatalytic water splitting. This is conducive to understand the interaction between the cocatalysts and O functional group on O-CN and the design of high-efficiency photocatalysts.