Atomic‐Scale CoO_x Species in Metal–Organic Frameworks for Oxygen Evolution Reaction

Abstract

The activity of electrocatalysts strongly depends on the number of active sites, which can be increased by downsizing electrocatalysts. Single-atom catalysts have attracted special attention due to atomic-scale active sites. However, it is a huge challenge to obtain atomic-scale CoO x catalysts. The Co-based metalorganic frameworks (MOFs) own atomically dispersed Co ions, which motivates to design a possible pathway to partially on-site transform these Co ions to active atomic-scale CoO x species, while reserving the highly porous features of MOFs. In this work, for the first time, the targeted on-site formation of atomic-scale CoO x species is realized in ZIF-67 by O 2 plasma. The abundant pores in ZIF-67 provide channels for O 2 plasma to activate the Co ions in MOFs to on-site produce atomic-scale CoO x species, which act as the active sites to catalyze the oxygen evolution reaction with an even better activity than RuO 2 .

Extraction of nickel from NiFe-LDH into Ni2P@NiFe hydroxide as a bifunctional electrocatalyst for efficient overall water splitting

“…Electrochemical water splitting has been regarded as a promising method for the production of hydrogen, using electric energy coming from intermittent solar energy and wind energy sources 2. However, water splitting is a thermodynamically uphill process, accompanied by high overpotentials ( η ) for both HER and OER, which requires efficient and stable electrocatalysts to significantly reduce the overpotentials 3. As is well known, Pt-based materials and iridium oxides are the state-of-the-art electrocatalysts for HER and OER, respectively,4 while their high cost and scarcity seriously limit their large-scale application.…”

Scalable Fabrication of Highly Active and Durable Membrane Electrodes toward Water Oxidation

“…In the overall water splitting, oxygen evolution reaction (OER) is a half reaction that involves the four‐electron transfer process, the oxidation of two water molecules to form a OO bond and the release of O 2 molecules from catalyst surface, thereby occupying the dominant part of overpotential . For this reason, it is a highly challenging task to design electrodes toward efficient OER in both commercial and scientific perspectives . In the past years, tremendous efforts have been focused on the development of OER catalytic materials, and a variety of materials have been developed to show superior performance to the commonly used commercial RuO 2 .…”

Rational Design of Transition Metal‐Based Materials for Highly Efficient Electrocatalysis

“…h) LSV curves for OER on ZIF‐67, CoO x ‐ZIF, CoO x ‐ZIF/C, and RuO 2 . Reproduced with permission . Copyright 2017, Wiley‐VCH.…”