Cyano-bridged Schottky junction of CN-TiC for enhanced photocatalytic H2 evolution and tetracycline degradation

Abstract

The electron collection and accumulation at carbon nitride (CN) surfaces play critical roles in coupling multielectron processes with carriers' dynamics for boosting tetracycline (TC) degradation, where MXenes are excellent candidates for tailoring carriers' dynamics in CN. Cyano-intermediated heterojunctions between CN and titanium carbide (CN-TiC) were synthesized via TiC-assisted thermopolymerization. Mesoporous morphology and combination of two materials were confirmed. Investigations on optical properties indicate that cyano groups were formed via this TiC-assisted polymerization, leading to strong chemical-physical interaction for intimate hetero-contact and enhanced visible absorption. As results, the optimized CN-TiC shows improved TC degradation rate (k = 0.05292 min−1), 3.5 times higher that of CN (k = 0.0153 min−1) or 176 times that of TiC (0.0003 min−1). Kinetics investigations reveal that superoxide radicals (.O2–) dominate TC oxidation, where TiC facilitates electrons' transportation/collection. Further photochemical investigations and band analysis suggest that the formation of Schottky junction between CN and TiC promotes electron-hole separation/transportation and electrons' accumulation for boosting TC degradation. We expanded this design to photocatalytic H2 evolution (PHE) or rhodamine degradation, achieving the PHE rate of 1941 μmol·g−1·h−1 or rhodamine removal ratio of 96%, far higher than that of CN.