Cationic surface polarization centers on ionic carbon nitride for efficient solar-driven H_(2)O_(2) production and pollutant abatement

Solar-driven H_(2)O_(2)production and emerging organic pollutants(EOPs)elimination are of great significance from the perspective of environmental sustainability.The efficiency of the photocatalytic reaction system is the key challenge to be addressed.In this work,the strategy of constructing surface ionic local polarization centers to enhance the exciton dissociation of the polymeric photocatalytic is demonstrated.Selected bipyridinium cation(TMAP)is complexed on a K^(+)-incorporated carbon nitride(CNK)framework,and the combination of local polarization centers both on the surface(bipyridinium cation)and bulk(K+cation)contributes to a superior photocatalytic H_(2)O_(2)production performance,affording a remarkable H_(2)O_(2)generation rate of 46.8μmol h^(-1)mg^(-1)and a high apparent quantum yield(AQY)value of 77.5%under irradiation of 405 nm photons.As substantiated experimentally by steady state/transient spectroscopy techniques,the surface local polarization centers increase the population of the long-lived trapped electrons,and thereby promote the interfacial charge transfer process for chemical conversion reaction.The strategy is potentially applicable to the design of a wide range of efficient solar-to-chemical conversion systems.

Molecular engineering towards dual surface local polarization sites on poly(heptazine imide)framework for boosting H_(2)O_(2) photo-production

The selective 2e^(−)ORR reaction on polymeric carbon nitride framework is one of the most promising approaches for solar-driven hydrogen peroxide production.Poly(heptazine imide)(PHI)as a class of K+-incorporated crystalline carbon nitride framework,is highly active for photocatalytic H_(2)O_(2)production.An upgrade on the H_(2)O_(2)photoproduction performance of PHI is realized and the mechanistic insights are revealed in this work.By photochemical reaction,the electron withdrawing groups of hydroxyl group and cyano group are grafted on the surface of PHI frameworks.The dual polarization sites on the sur-face contribute significantly to the enhancement of the exciton dissociation.The optimized PHI with dual polarization sites exhibits a remarkable photocatalytic H_(2)O_(2)production performance,which is 2times of the active pristine PHI.Most importantly,the photochemical reaction method is generally applicable to improve the exciton dissociation of a wide range of polymeric carbon nitride frameworks with vari-ous structure and compositions;and the thiourea-derived polymeric carbon nitride framework with dual surface polarization sites exhibits a remarkable photocatalytic performance with a high H_(2)O_(2)production rate of 40.5 mmol h^(−1)g^(−1).