Bimetal single atom on defect-tailoring carbon nitride that boosts photocatalytic hydrogen evolution and superfast contaminant degradation

Bimetal single atom functionalized porous carbon nitride (K1Na1/pCN) is designed by one-step method of forming defective carbon nitride and anchoring single atom, which constructs an efficient transfer channel for charge carriers via selective tailoring and linking heptazine rings in frameworks. The existence of single atom over pCN substrate is proved by special aberration corrected transmission electron microscope, X-ray absorption near-edge structures and X-ray photoelectron spectroscopy. The as-prepared K1Na1/pCN presents superior activity towards hydrogen evolution (4,561 μmol/h/gPt, AQY is 21.8% at 420 nm) and ciprofloxacin degradation (apparent kinetic constant of 0.74 min−1), which are almost one-order and two-order of magnitude larger than the traditional carbon nitride, respectively. Results of experimental data and density functional theory reveal that the K1Na1/pCN can narrow bandgap, form midgap state and provide more effective active sites, which have a synergistic effect on inhibiting charge carrier recombination and improving their directional transfer. This paper proposes an alternative strategy to synthesize carbon nitride-supported single atom by a one-step method and extends to support other metal single atoms via facile alternatives of molten salts.