Boosting photocatalytic hydrogen evolution enabled by SiO2-supporting chiral covalent organic frameworks with parallel stacking sequence
Two-dimensional covalent organic frameworks(2D COFs)feature extended π-conjugation and ordered stacking sequence,showing great promise for high-performance photocatalysis.Periodic atomic frameworks of 2D COFs facilitate the in-plane photogenerated charge transfer,but the pre-cise ordered alignment is limited due to the non-covalent π-stacking of COF layers,accordingly hindering out-of-plane transfer kinetics.Herein,we address a chiral induction method to construct a parallelly superimposed stacking chiral COF ultrathin shell on the support of SiO2 microsphere.Compared to the achiral COF analogues,the chiral COF shell with the parallel AA-stacking structure is more conducive to enhance the built-in electric field and accumulates photogenerated electrons for the rapid migration,thereby affording superior photocatalytic performance in hydrogen evolu-tion from water splitting.Taking the simplest ketoenamine-linked chiral COF as a shell of SiO2 parti-cle,the resulting composite exhibits an impressive hydrogen evolution rate of 107.1 mmol g-1 h-1 along with the apparent quantum efficiency of 14.31％at 475 nm.Furthermore,the composite photocatalysts could be fabricated into a film device,displaying a remarkable photocatalytic per-formance of 178.0 mmol m-2 h-1 for hydrogen evolution.Our work underpins the surface engineer-ing of organic photocatalysts and illustrates the significance of COF stacking structures in regulating electronic properties.
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