Hierarchical Manganese-Doped ZIFs Heterostructure Electrocatalysts for Highly-Efficient Methanol Oxidation Reaction

The development of cost-effective and high-performance electrocatalysts for methanol oxidation reaction (MOR) is essential to promote the hydrogen energy technology. However, most of the electrocatalysts currently used for MOR have drawbacks, such as inefficient reaction kinetics, low tolerance to carbon monoxide poisoning, and unstable performance. Herein, we report a novel hierarchical MOF heterostructure that is made up of Mn-doped ZIF67 and Mn-doped ZIF-L (Mn-ZIF67/L) directly grown on carbon cloth to highly enhance the MOR performance. Such heterostructure integrates flake-like Mn-doped ZIF-L with Mn-doped ZIF-67 nanocrystals, forming a porous core-shell framework with abundant active sites and enhanced charge transportation. More interesting, the Mn-ZIF67/L experiences dynamic reconstruction (Mn-ZIF67/L-ac) that partial phases in CoMn LDHs are transformed into (Co,Mn)OOH during the electrochemical operation in which further boosting the catalytic performance and stability. The electrochemical results demonstrate that Mn-ZIF67/L-ac remarkably improves the MOR performance with the much lower potential of 1.359 V at 10 mA cm^-2, outperforming commercial RuO₂. The electrocatalyst also delivers the high MOR stability of ∼97% retention after 130 h. This work demonstrates a robust strategy for nonnoble-metal electrocatalysts and an efficient route to hydrogen production through MOR-HER coupling.