Oct 4 2016
Gibeon Meteorite, By Hannes Grobe (Own work) [CC BY 3.0], via Wikimedia Commons
The electrocatalytic operation of an iron-based Gibeon meteorite for the oxygen evolution reaction (OER) discovered by Dr. Le Formal could rival the advanced performance of OER catalysts. The surprising findings are published in the journal Energy & Environmental Science.
As naturally-occurring metallic minerals have a unique formation history and atomic composition, exploring the electrocatalytic performance of these minerals is useful for energy conversion applications. The Gibeon meteorite, after ageing under working conditions in an alkaline electrolyte, produces an activity matching or potentially slightly superior to the high performing OER catalysts, with steady overpotentials that can be as low as 270 mV for 10 mA cm2 and Tafel slopes of 37 mV decade-1.
The Faradaic yield for the OER was unity and there was no decline in performance during 1000 hours of OER process at 500 mA cm2. Mechanical studies recommend an operando surface modification that includes the development of a 3D oxy(hydroxide) layer using a metal atom composition of primarily Co0.11Fe0.33Ni0.55, as specified by XPS and Raman studies, and trace Ir as specified from the elemental analysis.
The development of the catalyst layer was self-limiting to a depth of ca. 200 nm after ca. 300 hours of performance as specified through XPS depth-profiling data and cyclic voltammetry. The Gibeon meteorite’s unique structure and composition suggest that additional research on Ir–Co–Ni–Fe systems or other naturally occurring alloys for water oxidation can be a point of interest.
Source: http://actu.epfl.ch/