The highly efficient chemoselectivity, stereoselectivity, and regioselectivity render enzyme catalysis an ideal pathway for the synthesis of various chemicals in broad applications. While the cofactor of an enzyme is necessary but expensive, the conversed state of the cofactor is not beneficial for the positive direction of the reaction. Cofactor regeneration using electrochemical methods has the advantages of simple operation, low cost, easy process monitoring, and easy product separation, and the electrical energy is green and sustainable. Therefore, bioelectrocatalysis has great potential in synthesis by combining electrochemical cofactor regeneration with enzymatic catalysis. In this review, we detail the mechanism of cofactor regeneration and categorize the common electron mediators and enzymes used in cofactor regeneration. The reaction type and the recent progress are summarized in electrochemically coupled enzymatic catalysis. The main challenges of such electroenzymatic catalysis are pointed out and future developments in this field are foreseen.

The hollow spherical covalent organic frameworks (COFs) have a wide application prospect thanks to their special structures. However, the controllable synthesis of uniform and stable hollow COFs is still a challenge. We herein propose a self-templated method for the preparation of hollow COFs through the Ostwald ripening mechanism under ambient conditions, which avoids most disadvantages of the commonly used hard-templating and soft-templating methods. A detailed time-dependent study reveals that the COFs are transformed from initial spheres to hollow spheres because of the inside-out Ostwald ripening process. The obtained hollow spherical COFs have high crystallinity, specific surface area (2,036 m²·g⁻¹), stability, and single-batch yield. Thanks to unique hollow structure, clear through holes, and hydrophobic pore environment of the hollow spherical COFs, the obtained immobilized lipase (BCL@H-COF-OMe) exhibits higher thermostability, polar organic solvent tolerance, and reusability. The BCL@H-COF-OMe also shows higher catalytic performance than the lipase immobilized on non-hollow COF and free lipase in the kinetic resolution of secondary alcohols. This study provides a simple approach for the preparation of hollow spherical COFs, and will promote the valuable research of COFs in the field of biocatalysis.