Fine tuning of supported covalent organic framework with molecular active sites loaded as efficient electrocatalyst for water oxidation

Covalent organic frameworks (COFs) with internal fixation of molecular active sites provide unprecedent high atom utilization and selectivity in various electrocatalysis. So far, it is still big challenge to exploit their fine tuning to enhance the catalytic performance and have insight into their advantages. In this paper, we report an ideal platform construed by COFs and multiwall carbon nanotubes (MWCNTs) to illustrate key factors in COF-based electrocatalysts towards oxygen evolution. Fine tuning of COF layers reveals the optimized catalytic performance relies on the proper loadings of molecular catalyst on MWCNTs to balance the mass and electron transfer. Moreover, a novel strategy of diluting the active sites to enhance their intrinsic activity is proposed to further enhance the electrocatalytic performance. The generality of the fine regulation is fully demonstrated with different COFs. This work elucidates the fine tuning of COF-based electrocatalysts and sheds light on the broad applications of molecular catalysts.