Modulation of electronic density in ultrathin g-C3N4 for enhanced photocatalytic hydrogen evolution through an efficient hydrogen spillover pathway

The high recombination of photoinduced electron-hole and deep charge trapping in graphitic carbon nitride (g-C3N4)-based photocatalysts have limited the photocatalytic activity in hydrogen evolution reaction (HER). Here, we proposed the synergistic strategies of electron-deficient boron (B) and electron-rich phosphorus (P) doped g-C3N4 (BPCN) through tuning the electron density for enhanced photocatalytic activity in HER under visible light irradiation. The BPCN exhibited highest photocatalytic activity in HER with the apparent quantum efficiency of 17.4% at 400 nm superior to reported g-C3N4-based photocatalysts. The remarkable activity in HER was attributed to the efficient charge separtion by the shallow charge capture, electron transfer from P to B and the efficient hydrogen spillover pathway occurred by the strong absorption H2O at P sites and then H transferring to B sites. This work paves a new route to changing the electronic density with the tunable band structures through the doping engineering for enhanced photocatalytic activity.