Researchers from the Technische Universität Dresden, with colleagues from Jiangnan University and Wenzhou University in China, have developed various noble metal aerogels (NMAs), with unprecedented potential for diverse pH-universal electrochemical catalysis, including oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and electrochemical water splitting.

These findings largely span the application territory of NMAs for fuel cells, green hydrogen production and many more. An open-access paper on the work is published in the journal Advanced Energy Materials.

New-type noble metal aerogels were developed for outstanding pH-universal electrocatalysis toward hydrogen evolution reaction and oxygen reduction reaction. Credit: Wiley-VCH

Electrocatalysis is one of the most studied topics in the field of material science, because it is extensively involved in many important energy-related processes, such as the oxygen reduction reaction (ORR) for fuel cells, the hydrogen evolution reaction (HER) for green hydrogen production, and the oxygen evolution reaction (OER) for metal-air batteries.

NMAs are emerging as a new class of outstanding electrocatalysts due to the combined feature of metals and aerogels. However, limited by the available compositions, the explored electrocatalytic reactions on NMAs are highly restricted and certain important electrochemical processes have not been investigated.

By adopting a strong salting-out agent (i.e. ammonium fluoride (NH₄F)) as an initiator to trigger gelation, the composition of the as-obtained noble metal aerogels (NMAs) was extended to various bi- and trimetallic systems. Subsequently, the researchers manipulated the chemical composition, and thus expanded the application territory of NMAs to pH-universal ORR electrocatalysis, HER electrocatalysis, and electrochemical water splitting.

Notably, an Au-Rh aerogel and Au-Pt aerogel manifested extraordinary pH-universal performance for HER and ORR electrocatalysis, respectively, both of which considerably outperform commercial Pt/C (platinum on carbon) in wide pH environments.

Further research directions may be placed on morphology-controlled NMA synthesis, and the establishment of the correlations between the structural features of NMAs and their electrocatalytic properties.

—lead author Ran Du

Resources

• Du, R., Jin, W., Hübner, R., Zhou, L., Hu, Y., Eychmüller, A. (2020) “Engineering Multimetallic Aerogels for pH‐Universal HER and ORR Electrocatalysis.” Adv. Energy Mater. 10, 1903857 doi: 10.1002/aenm.201903857