Hybridization of MXene and covalent organic frameworks as electroactive materials for Li–S batteries and oxygen electrocatalysis†

Based on the terrible situation of energy shortage and environmental pollution, the research and development of multifunctional electrochemical materials for application in the field of renewable, pollution-free, and effective energy conversion and storage is currently a hot topic. It is worth noting that the hybridization of organic and inorganic materials can not only alleviate the poor electrical conductivity of organic materials but also prevent the aggregation and oxidation of inorganic materials, which is beneficial for the electrochemical process. Herein, a series of multifunction organic–inorganic hybrids have been successfully prepared through in situ polymerization of COF-TpDb nanolayers on the surface of Ti₃C₂T_x MXene sheets, followed by post-functionalization of the composites. Among these hybrids, the MX@COF-TpDb modified S-cathode exhibits higher initial specific capacity and better cycle durability than pure COF-TpDb in lithium–sulfur (Li–S) batteries, which is mainly due to the intervention of MXene that accelerates Li⁺ diffusion. Furthermore, the working electrode assembled with Fe/Co-MX@COF-TpDb-AO demonstrates the lowest overpotential compared to other metal coordination hybrids, which is primarily attributed to the synergistic effect of iron and cobalt ions that facilitates the electrocatalytic oxygen evolution process. Equally important, Co-MX@COF-TpDb-AO shows an electrocatalytic oxygen reduction pathway close to 4e⁻ and low H₂O₂ yield, which is comparable to most discovered COF-containing materials. Therefore, the idea of constructing MXene/COF hybrids sheds some light on the exploration of multifunctional electrochemical materials.