Enhancing Oxygen Evolution Reaction Performance in Prussian Blue Analogues: Triple-Play of Metal Exsolution, Hollow Interiors, And Anionic Regulation.

Abstract

Prussian blue analogs (PBAs) are promising catalysts for green hydrogen production. However, the rational design of high-performing PBAs is challenging, which requires an in-depth understanding of catalytic mechanism. Here FeMn@CoNi core-shell PBAs were employed as precursors, together with Se powders, in low-temperature pyrolysis in an argon atmosphere. This synthesis method enabled the partial dissociation of inner FeMn PBAs that resulted in hollow interiors, Ni nanoparticles (NPs) exsolution to the surface, and Se incorporation onto the PBA shell. The resulting material presented ultra-low oxygen evolution reaction (OER) overpotential (184mV at 10mA cm-2 ) and low Tafel slope (43.4mV dec-1 ), outperforming leading-edge PBA-based electrocatalysts. The mechanism responsible for such a high OER activity was revealed, assisted by DFT calculations and the surface examination before and after the OER process.The exsolved Ni NPs were found to help turn the PBAs into Se-doped core-shell metal oxyhydroxides during the OER, in which the heterojunction with Ni and the Se incorporation were combined to improve the OER kinetics. This work shows that efficient OER catalysts could be developed by using a novel synthesis method backed up by a sound understanding and control of the catalytic pathway. This article is protected by copyright. All rights reserved.