Decarboxylation-Induced Defects in MOF-Derived Single Cobalt Atom@Carbon Electrocatalysts for Efficient Oxygen Reduction

Developing transition metal single-atom catalysts (SACs) for oxygen reduction reaction (ORR) is of great importance. Zeolitic imidazolate frameworks (ZIFs) as a subgroup of metal-organic frameworks (MOFs) are distinguished as SAC precursors, due to their large porosity and N content. However, the activity of the formed metal sites is limited. Herein, we report a decarboxylation-induced defects strategy to improve their intrinsic activity via increasing the defect density. Carboxylate/amide mixed-linker MOF (DMOF) was chosen to produce defective Co SACs (Co@DMOF) by gas-transport of Co species to DMOF upon heating. Comparing with ZIF-8 derived SAC (Co@ZIF-8-900), Co@DMOF-900 with more defects yet one fifth Co content and similar specific double-layer capacitance show better ORR activity and eight times higher turnover frequency (2.015 e s(-1) site(-1)). Quantum calculation confirms the defects can weaken the adsorption free energy of OOH on Co sites and further boost the ORR process.

Automated summary

The study focuses on developing transition metal single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) by using a decarboxylation-induced defects strategy to enhance their intrinsic activity. A gas-transport method was used to produce defective Co SACs (Co@DMOF) from carboxylate/amide mixed-linker MOF (DMOF), showing improved ORR activity compared to Co@ZIF-8-900.