Generating, probing and utilising photo-induced surface oxygen vacancies for trace molecular detection

Metal oxide semiconductors (MOS) are extensively used for a wide range of industrial applications [1] – [3] , where defects states in MOS can strongly affect their overall performance, even at very low concentrations [4] , [5] . The functionality of MOS has been reported to be significantly altered through the addition of defects, whereby the materials can become more/less chemically active or the electronic properties are altered. Surface defects, in particular, are often one of the most reactive sites on the surface, greatly influencing MOS photocatalytic activity. Under UV irradiation conditions, interactions with photo- induced charge carriers can generate temporary oxygen vacancies, VO, defect states on the surface of MOS [6] , affecting the material properties during the defects’ lifetime.