Engineering Work Function to Stabilize Metal Oxides in Reactive Hydrogen

TL;DR

This paper shows how adjusting the work function of metal oxides can stabilize them in hydrogen environments, preventing degradation.

Contribution

The work function is proposed as a tunable parameter to control hydrogen–material interactions in transition metal oxides.

Findings

Increasing the fraction of low-work function transition metals lowers the oxide's work function.

Lower work function reduces reducibility in hydrogen radicals, stabilizing high-oxidation-state metals.

Work function modulation offers a strategy to enhance material stability in reactive hydrogen.

Abstract

Hydrogen, crucial for the green energy transition, poses
a challenge
due to its tendency to degrade surrounding wall materials. To harness
hydrogen’s potential, it is essential to identify the parameter(s)
of materials that modulates hydrogen–material interaction.
In a recent publication, we have shown that the reduction (denitridation)
of transition metal (TM) nitrides in hydrogen radicals (H*) stops
when their work function drops below a threshold limit. In this work,
we tailor the work function of a complex TM oxide by tuning the relative
contents of its constituent TM atoms. We show that increasing the
fraction of a low-work function TM decreases the work function of
the complex oxide, thereby decreasing its reducibility (deoxidation)
in H*. This leads to the stabilization of the higher oxidation states
of a high-work function TM, which otherwise would be readily reduced
in H*. We propose that the work function serves as a tunable parameter,
modulating the interaction of hydrogen with TM compounds.

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