NMR Study On The Structure Design Of Photocatalysts And The Impact On Material Exchange In Real Solid-Liquid Systems

The development of nuclear magnetic resonance?NMR?technology provides new possibilities for precise observation of the structure of substances and in situ detection,which can be used to observe the interaction between catalysts and liquid and the effect of catalyst on reaction environment in real solid?catalyst?-liquid reaction systems.In this study,we focus on two classic catalysts?titanium dioxide and carbon nitride?in photocatalysis,NMR methods were used to study catalyst inherent properties and the correlation between the structural properties of the catalyst and the reaction environment,and link them to the photocatalytic efficiency:1.Operando NMR method was used to investigate the interaction between water and methanol in the process of the photocatalytic methanol reforming in a real solid-liquid environment.The existence of hydrogen bonding and proton exchange between water and methanol was proved.The introduction of catalyst,the reaction temperature and light irradiation may influence on the strength of hydrogen bonds and the proton exchange efficiency,which then affect the methanol reforming efficiency.This results indicate that the selection of the appropriate temperature can benefit the improvement of methanol reforming efficiency.2.A new method to replace the hydrogen-containing reaction environment with deuterated reagents was introduced.A series of one-dimensional?1D?and two-dimensional?2D?solid-state NMR?SSNMR?experiments were carried out to detect hydrogen-containing carbon nitride?C₃N₄?catalysts to study the relationship between hydrogen-containing structure and the reaction environment.C₃N₄ catalysts were obtained from urea precursors at different temperatures and treated with deuterium-oxide.The results indicate that the hydrophilic amine group?mainly in the form of–NH-?on the C₃N₄ framework may bear the active site of the catalyst for photocatalytic water splitting to produce hydrogen.In addition,the catalyst inherent and the appropriate hydrogen bonding interaction with water can promote the connection between the catalyst and the reaction environment,which cause the promotion of proton exchange,and thus exhibit higher photocatalytic hydrogen evolution reaction?HER?activity.This research provides new ideas for studying the interaction between catalysts and the environment,also make sense in designing photocatalysts.