The widespread adoption of renewable energy technologies such as wind and solar brings us closer to the eradication of the burning of fossil fuels while still meeting our rapidly growing energy demands. Unfortunately, the intermittency of these energy sources has prevented them from acting as a primary energy source. To mitigate these issues, the electrochemical splitting of water (2H₂O -> 2H₂+ O₂) has emerged as a promising process for storing renewable energy in the form of H₂(g), a chemical fuel. The efficiency of the water splitting process is greatly reliant on the performance of the sluggish oxygen evolution reaction (OER). The OER is a kinetically demanding four electron process; therefore, potent OER catalysts (OERCs) are required to drive the reaction at appreciable rates.

In the development of OERCs, transition metal oxides have demonstrated both high stability and activity, with ruthenium, iridium, and platinum containing catalysts emerging as superior candidates. At the same time, amorphous catalysts have been proven higher catalytic activities for small-molecule transformations (i.e., OER) when compared against their crystalline counterpart. For example, amorphous ruthenium oxide (RuO_x) has been empirically shown to be a superior OERC, but the mechanistic nature of this catalyst is not agreed upon in the literature.

In this presentation I will discuss the performance of amorphous RuO_x OER catalysts produced by various synthetic methods and give mechanistic insights gleaned from in-operando synchrotron-based X-ray absorption spectroscopy (XAS) techniques. In conjunction with the synchrotron-based work, a density functional theory (DFT) study of the RuO_x system will be carried out to corroborate the experimental results. This combination of spectroscopic experiment and computational chemistry will enhance our understanding of the fundamentals behind the superior performance of amorphous RuO_x, ultimately leading to the development of design principles for future OERC’s.

Santiago Jimenez

Appearances