Oxygen Defects in Nanostructured Metal-Oxide Gas Sensors: Recent Advances and Challenges†

Defect engineering has been the most promising strategy to modulate the surface microstructure and electronic structure of the metal oxides, which will govern the efficiency of a given oxide for the applications in heterogeneous catalysis, energy storage and conversion fields, and gas sensing. This review summarizes recent research advances on understanding the role of oxygen vacancies of the metal oxides in gas sensing. First, different strategies for oxygen vacancy productions are summarized and compared. Then, the proper characterization techniques for oxygen vacancy are introduced. Importantly, the structure-activity relationships between vacancy engineering and gas sensing ability are further illustrated coupling the experimental results and theoretical studies. Finally, the key challenges and prospects regarding defect engineering in gas sensing are highlighted.