Molecular-MN4 vs atomically dispersed M-N4-C electrocatalysts for oxygen reduction reaction

The scientific community's concerns in the realm of renewable energy give logical motives to develop effective electrocatalysts for O-2 electrocatalysis, oxygen reduction reaction (ORR) in particular. For this purpose, molecular electrocatalysts, especially bio-inspired metal-N-4-complexes and metal-nitrogencarbon (M-N-4-C) materials, have been widely used as potential electrocatalysts. Although the M-N-4-C materials do not possess the precise ability to control reactivity and selectivity, they are found to be durable and easier to process at a practical level. Whereas molecular electrocatalysts can be tuned easily by chemical treatment so that their reactivity and selectivity resemble the desired electrocatalytic reaction. However, their limited activity and durability is a bottleneck issue at the practical level and encourages to benchmark their performance, and to figure out exact activity descriptors to design advanced MN4-molecular as well as atomically dispersed M-N-4-C electrocatalysts with excellent performance. The main goal of this review is to highlight the gap in mutual understanding between molecular MN4 and atomically dispersed M-N-4-C active sites, to bridge that gap by matching several activity descriptors, and to update the recently adopted strategies to benchmark the catalytic performance of both molecular-MN4 and atomically dispersed M-N-4-C electrocatalysts. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This article highlights the motivation for developing efficient O-2 electrocatalysts and the application of molecular electrocatalysts, pointing out the challenges in activity and durability of M-N-4-C materials, and introduces ways to optimize their performance through chemical treatment.