Operando characterization techniques for electrocatalysis
The energy crisis and climate change are growing threats to human society. Fuel cells and electrolyzers using solar and wind as energy sources provide a promising carbon-free and sustainable energy future as an alternative to the present fossil fuels. Robust and efficient electrocatalysts constitute the cornerstone for practical applications of fuel cells and electrolyzers. However, their rational design is hindered by the lack of knowledge of the active site structures, the reaction pathways, and the degradation mechanisms. This calls for the operando characterization of the electrode–electrolyte–gas interface of electrocatalytic processes under working conditions. This review describes the understanding of various operando techniques for diverse nano-, molecular and single atom electrocatalysts. We highlight the progress achieved via operando techniques toward the elucidation of the structure–activity relationships of electrocatalysts.