Silver Nanocatalysts Switch Reaction Sites for Energy Production

Researchers have discovered that silver nanocatalysts can change their active reaction sites within solid oxide cells, depending on whether the cell is generating electricity or producing hydrogen. This finding offers a new approach to designing more efficient next-generation energy devices. The study was led by Professors WooChul Jung and Jeong Woo Han at Seoul National University, in collaboration with Professor Sang Ouk Kim's team at KAIST and Dr. Beomgyun Jeong's team at the Korea Basic Science Institute.

Solid oxide cells are versatile devices that can either generate electricity or split water to produce hydrogen by moving oxygen ions through a solid material. This dual capability makes them important for expanding clean energy and hydrogen use. The performance and durability of these cells rely heavily on the speed of oxygen reactions at the air electrode. Previous research indicated that metal nanocatalysts improve cell function, but the exact location and mechanism of their catalytic activity remained unclear.

The research team developed a model electrode with precisely controlled structures and compositions to investigate these questions. They compared several metal nanocatalysts, including silver, cobalt, palladium, and platinum, deposited on a thin film perovskite oxide electrode. Silver demonstrated the most significant catalytic improvement among the tested metals. Further analysis revealed that during electricity generation, the interface between silver nanoparticles and the electrode was the primary reaction site. However, during hydrogen production, the surface of the silver nanoparticles themselves became the main reaction site.

This indicates that the same nanocatalyst can perform its key chemical reactions in different locations based on the operating mode of the energy device. The researchers also found that silver nanocatalysts facilitate electron transfer to oxygen during electricity generation and assist oxygen atoms in combining into molecules during hydrogen production. These insights suggest a new design strategy for solid oxide cells, where the catalyst surface and the catalyst-electrode interface can be optimized separately. Such advancements could lead to more efficient electricity generation and reduce the energy required for green hydrogen production.