An international group of scientists have used theoretical predictions to fabricate a new rare earth catalyst that helps the oxygen evolution reaction.
A group of researchers have used theoretical predictions to identify and fabricate a new electrocatalyst that aids the oxygen evolution reaction.
The paper ‘Reinforcing Co-O Covalency via Ce(4f)─O(2p)─Co(3d) Gradient Orbital Coupling for High-Efficiency Oxygen Evolution,’ was published in Advanced Materials.
Achieving a more efficient oxygen evolution reaction process
Water-splitting electrolysers harness electrolysis to uncouple hydrogen from oxygen.
The hydrogen produced can be used as a clean fuel. The oxygen gas can be utilised for medical purposes, industrial processes, or simply released into the atmosphere.
The oxygen evolution reaction, the point where water molecules are oxidised at the anode, is a barrier to these wider applications. This is because the oxygen evolution reaction causes energy loss and requires extra voltage to drive the reaction.
To overcome this barrier and achieve a more efficient oxygen evolution reaction process, scientists have turned to a rare earth catalyst that utilises rare-earth based transition metal oxides.
However, these are based on expensive and scare metals, further limiting their industrial application.
Furthermore, how they work remains a mystery.
“The predictive power of theory helped us overcome this shortcoming,” said Hao Li, associate professor at Tohoku University’s Advanced Institute for Materials Research (WPI-AIMR) and corresponding author of the paper.
“Given that finding effective and low-cost OER catalysts requires a lot of trial-and-error, we used theory to predict that doping cerium (Ce) into cobalt oxides (CoO) would lead to a better performing and more stable electrocatalyst.”
The group’s predictions proved true
Using a special plasma technique, the team combined cerium with cobalt oxide before running tests on the material.
The results confirmed the favourable performance. The results demonstrated an overpotential of only 261 mV at 10 mA cm−2 and robust electrochemical stability, superior to individual CoO.
X-ray absorption spectroscopy and in situ electrochemical Raman spectroscopy showed that the cerium atoms made the cobalt oxide stronger. This was because it changed how the atoms are connected, leading to a more efficient oxygen evolution reaction.
The team believe that their breakthrough can lead to future developments in rare earth catalysts
The team are confident that the work can lead to creating more efficient rare earth catalysts in the future.
“We believe our Ce-CoO model can serve as a basis for the mechanistic understanding and structural design of high-performance RE-TMO catalysts.”
