Mxene quantum dot insertion-induced electron transfer in CoFe LDH for high-performance zinc-air batteries

Cobalt-iron layered double hydroxide (CoFe LDH), a promising air cathode material for rechargeable zinc-air batteries (ZABs), faces significant challenges in practical applications due to its low oxygen evolution reaction (OER) catalytic activity and the ambiguity in identifying its active sites. To address these issues, this study introduces MXene quantum dots (MQDs) into CoFe LDH, fabricating a CoFe LDH/MQD/Co@NF composite with enhanced interfacial electronic coupling. This integration induces electron transfer from CoFe LDH to MQDs, leading to the pre-oxidation of Co ions into higher-valence Co 3+ states, as confirmed by X-ray photoelectron spectroscopy, and optimizing OER intermediate adsorption kinetics. Density functional theory (DFT) calculations reveal cobalt as the primary active site, highlighting its critical role in boosting catalytic activity. The composite exhibits a low OER overpotential of 192 mV at 10 mA cm −2 , a Tafel slope of 36.3 mV dec -2 , a maximum power density of 136.5 mW cm −2 , and a high specific energy of 626 mA h g −1 in ZABs, with exceptional durability over an 85-hour cyclic test. These results demonstrate that MQD incorporation significantly improves OER catalytic activity and enhances ZAB performance, offering a promising strategy for designing high-performance, long-lasting electrocatalysts and advancing electrochemical energy storage technologies.