Near‐Field Drives Long‐Lived Shallow Trapping of Polymeric C3N4 for Efficient Photocatalytic Hydrogen Evolution

• Published in: Advanced functional materials Vol. 31; no. 35
• Main Authors: Wang, Wenchao, Bai, Xueqin, Ci, Qing, Du, Lili, Ren, Xingang, Phillips, David Lee
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01-08-2021
• Subjects: Carbon nitride; Charge transfer; Excitation; Heterojunctions; Hydrogen evolution; Hydrogen production; Indium oxides; Liquid phases; Materials science; near field assistance; Photocatalysis; shallow trapping; transient absorption spectroscopy; Trapping
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202103978

Undesired photoelectronic dormancy through active species decay is adverse to photoactivity enhancement. An insufficient extrinsic driving force leads to ultrafast deep charge trapping and photoactive species depopulation in carbon nitride (g‐C3N4). Excitation of shallow trapping in g‐C3N4 with long‐lived excited states opens up the possibility of pursuing high‐efficiency photocatalysis. Herein, a near‐field‐assisted model is constructed consisting of an In2O3‐cube/g‐C3N4 heterojunction associated with ultrafast photodynamic coupling. This In2O3‐cube‐induced near‐field assistance system provides catalytic “hot areas”, efficiently enhances the lifetimes of excited states and shallow trapping in g‐C3N4 and this favors an increased active species density. Optical simulations combined with time‐resolved transient absorption spectroscopy shows there is a built‐in charge transfer and the active species lifetimes are longer in the In2O3‐cube/g‐C3N4 hybrid. Besides these properties, the estimated overpotential and interfacial kinetics of the In2O3‐cube/g‐C3N4 hybrid co‐promotes the liquid phase reaction and also helps in boosting the photocatalytic performance. The photocatalytic results exhibit a tremendous improvement (34‐fold) for visible‐light‐driven hydrogen production. Near‐field‐assisted long‐lived active species and the influences of trap states is a novel finding for enhancing (g‐C3N4)‐based photocatalytic performance.
A near‐field‐assisted model containing an In2O3‐cube/g‐C3N4 heterojunction that can assist with ultrafast photodynamic coupling is constructed. Near‐field assistance is found to enhance long‐lived shallow charge trapping in g‐C3N4 so as to favor generating an increased photoactive species population. A mechanism for the photophysical and photochemical routes is deduced from time‐resolved spectroscopy combined with results from optical simulations.