An effective and simple oxygen nanosensor made from MPA-capped water soluble CdTe nanocrystals

CdTe semiconductor nanocrystals (NCs) with 3-mercaptopropionic acid as the ligand exhibit a reversible response towards inter-switching oxygen and argon environments. The photoluminescence response is investigated at multiple oxygen concentrations, NC coverage and excitation intensities, in which all conditions exhibit full recovery upon exposure to flowing argon. The CdTe NC's large surface-to-volume ratio results in high sensitivity towards oxygen molecules with significant photoluminescence quenching at a concentration of 40 ppm. This suggests a novel approach to the creation of simple, inexpensive and ultrasensitive oxygen nanosensors.