Docking MOF crystals on graphene support for highly selective electrocatalytic peroxide production

Tailoring the reaction kinetics is the central theme of designer electrocatalysts, which enables the selective conversion of abundant and inert atmospheric species into useful products. Here we show a supporting effect in tuning the electrocatalytic kinetics of oxygen reduction reaction (ORR) from four-electron to two-electron mechanism by docking metalloporphyrin-based metal-organic frameworks (MOFs) crystals on graphene support, leading to highly selective peroxide production with faradaic efficiency as high as 93.4%. A magic angle of 38.1 degrees tilting for the co-facial alignment was uncovered by electron diffraction tomography, which is attributed to the maximization of pi-pi interaction for mitigating the lattice and symmetry mismatch between MOF and graphene. The facilitated electron migration and oxygen chemisorption could be ascribed to the supportive effect of graphene that disperses of the electron state of the active center, and ultimately regulates rate-determining step.

Automated summary

Tailoring reaction kinetics is crucial in designer electrocatalysts for selectively converting atmospheric species into useful products. This study demonstrates a supportive effect in tuning the electrocatalytic kinetics of oxygen reduction reaction by attaching metalloporphyrin-based MOFs crystals onto graphene support, leading to highly selective peroxide production. The discovery of a magic angle for co-facial alignment optimization reveals the importance of maximizing pi-pi interaction for mitigating lattice and symmetry mismatch between MOF and graphene, ultimately facilitating electron migration and oxygen chemisorption.