Ice-templating co-assembly of dual-MOF superstructures derived 2D carbon nanobelts as efficient electrocatalysts

Here, we propose a novel synthetic strategy to fabricate a two-dimensional (2D) N-doped carbon nanobelt with high electrocatalytic activity using a dual-MOF superstructure precursor. The self-assembly mechanism induced by Van der Waals forces ensures the successful formation of a 2D ZIF-8/ZIF-67 dual-MOF superstructure through a straightforward ice-templating co-assembly method. Additionally, N-doped carbon derived from ZIF-8 can capture cobalt species from the adjacent ZIF-67 during the pyrolysis process, resulting in the coexistence of atomically dispersed Co single atoms and nanoparticles within the carbon nanobelt, effectively enhancing the intrinsic activity for the electrocatalytic oxygen reduction reaction (ORR). Furthermore, the interconnected hierarchically porous carbon nanocubes in the kinetic-favorable 2D carbon nanobelt superstructure can maximize the exposure of accessible active sites, overcome macroscopic mass transfer limitations, and accelerate the reaction kinetics. Hence, the as-prepared carbon nanobelt exhibits outstanding alkaline ORR catalytic activity with a half-wave potential of 0.888 V versus RHE, and the assembled Zn-air batteries display a prominent peak power density of 179 mW cm-1. The present work highlights the simplicity and versatility of the ice-templating assisted co-assembly strategy in preparing efficient 2D carbon-based superstructure electrocatalysts.

Automated summary

This work proposes a new synthetic strategy to fabricate a high electrocatalytic two-dimensional N-doped carbon nanobelt. The successful formation of a 2D ZIF-8/ZIF-67 dual-MOF superstructure is achieved through a ice-templating co-assembly method, with the N-doped carbon derived from ZIF-8 capturing cobalt species from adjacent ZIF-67 during the pyrolysis process. The resulting carbon nanobelt exhibits outstanding alkaline ORR catalytic activity.