Cucurbit[n]uril-Derived Electrocatalysts for Oxygen Evolution, Oxygen Reduction, and Hydrogen Evolution Reactions

Various sustainable energy conversion techniques like water electrolyzers, fuel cells, and metal-air battery devices are promising to alleviate the issues in fossil fuel consumption. However, their broad employment has been mainly inhibited by the lack of advanced electrocatalysts to accelerate the sluggish kinetics of the three involved half-reactions including oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). Recent advances have witnessed the cucurbit[n]uril (CB[n])-directed strategy as a prominent tool to develop high performance electrocatalysts with either OER, ORR, or HER activities. In this review, the recent progress on CB[n]-derived electrocatalysts ranging from molecular complexes to heterogeneous nanostructures and single-atoms for the three half-reactions are reviewed, and future opportunities are discussed. A concise introduction to the fundamentals of CB[n]s regarding their synthesis, structure, and chemistry is given first. Subsequently, the systematic summary of CB[n]-derived electrocatalysts and their performance for the OER/ORR/HER are discussed in detail, with a specific emphasis on correlating their structure and activities by combining diverse physiochemical characterizations, electrochemical experiments, and theory simulations. Finally, a brief conclusion and perspective for future opportunities regarding CB[n]-derived electrocatalysts for many other electrocatalytic applications are proposed.