Steering The Electronic Structure In G-C₃N₄:Photocatalytic NO_x Oxidation Enhancement Mechnism And Reaction Mechnism

Environmental pollution and energy shortage have become global concerns that need to be solved by advances in cutting-edge science and technology.NO_x,which is one of the major contributors to photochemical smog,acid rain and ozone depletion and is primarily responsible for respiratory and cardiopulmonary diseases,has triggered much social concern.Various renewable and sustainable technologies thus have been developed to address these challenges to date.Among them,semiconductor-based photocatalysis has gained interdisciplinary attention as a result of its great potential to harness solar energy for degradation of typical pollutants.Graphitic carbon nitride（CN）,a metal-free layered conjugated semiconductor,has been extensively applied in the area of environmental remediation and solar energy conversion owing to its facile synthesis,appealing electronic structure,high physicochemical stability,and“earth-abundant”nature.As a result of the polymeric character of CN,its electronic structure can be easily tailored by means of surface engineering at the atomic-level in order to enhance its photocatalytic performance.In particular,CN is limited by the intrinsic graphitic sp²-hybridized array of tri-s-triazine repeating units and the inert stack of layers,which enable delocalized photogenerated electrons to transfer in planes randomly,leading thus to a high charge-recombination rate.Therefore,the internal electronic structure of CN（intralayer electronic structure and interlayer electronic structure）can be rationally designed and tailored to promote the redistribution and delocalization of electrons for expedited spatial charge separation and thus accelerated generation of abundant reactive oxygen species（ROS）capable of participating in photocatalysis.First,we developed a facile one-step in situ co-pyrolysis of urea and SrCO₃ to synthesis SrO clusters@amorphous,which can adjust the intralayer electronic structure of CN for enhanced separation efficiency of carrier.Also,we craft interlayer bi-oriented electrons transportation channels via intercalation K⁺and NO₃^-species between the neighboring layers of CN,lowering the interlayer energy barrier and steering the interlayer charge flow.The charge flow induced by the two channels could transfer towards opposite directions,resulting in the significantly boosted separation and transportation efficiency of carriers.Consequently,the abundant electrons can be provided to activate the O₂ molecule and thus dramatically facilitates the production of ROS to participate in the photocatalytic redox reaction.Furthermore,base on our previous work,we first designed an O/Ba co-functionalized amorphous carbon nitride（labeled as O-ACN-Ba）through the highly combined theoretical and experimental method for short-range and directional charge transfer in electronic transportation channels.Local electronic trapping segments and surface electronic trapping adjusters are introduced into CN to induce the convergence and localization of delocalized intralayer electrons.Simultaneously,interlayer electronic trapping mediators are intercalated to bridge adjacent CN layers in order to direct the direction of electron transfer.The unique electronic structure O-ACN-Ba enables highly enhanced photocatalytic NO removal and suppresses the generation of toxic intermediate（NO₂）.Besides,even though most of the reported works have focused on the development of modification strategies to optimize photocatalytic performance,the conversion pathway of photocatalytic pollutant oxidation as a key issue has not been clearly revealed.Most importantly,the generation of possible toxic intermediates during photocatalytic reaction processes is typically neglected,despite the fact that it could result in the accumulation of secondary pollutants and decrease the photocatalytic performance.So we conbine the DFT calculation and in situ DRIFTS spectra to better understand the mechanism of NO adsorption on photocatalysts,simulated the production of·O₂^-by calculating the O₂ adsorption and thus elucidate the conversion pathways of photocatalytic NO oxidation.Therefore,the present work describes a novel strategy for the optimization of photocatalytic NO removal efficiency and simultaneous suppression of toxic intermediate generation,while also elucidating the mechanism underlying the photocatalytic reaction.This work proposes a novel strategy to advance the application of photocatalytic technology for safe and efficient air purification.