CuInS2 QDs decorated ring-like NiO for significantly enhanced room-temperature NO2 sensing performances via effective interfacial charge transfer

Abstract

Recently, quantum dots (QDs) decorated nanomaterials have attracted great attention in gas sensing fields, which usually exhibit largely enhanced sensing performance compared to unmodified nanomaterials. However, the reason behind the enhanced sensing performance remains unclear, such as the effect of interfacial electron transfer between QDs and substrate material on the sensing properties, quantum size effect, etc. Here, to improve the room-temperature sensing properties of NiO and reveal the QDs sensitization mechanism, together with morphological structure regulation, we report for the first time the application of the CuInS2 QDs in gas sensing fields. Interestingly, we found that the ring-like NiO modified with the CuInS2 QDs exhibited largely enhanced sensitivity to NO2 at room temperature, and the response of nanocomposites with optimal molar ratio to 60ppm NO2 is 10 times larger than that of bare NiO. The probable reason is that the quantum size of CuInS2 QDs with suitable energy band structure could have an effective electron transfer rate with the ring-like NiO. And the effective electron transfer from CuInS2 to NiO can facilitate the ionization of the neutral nickel vacancies, and then more charged Ni vacancies generated which can participate in gas reaction, leading to the largely enhanced sensing properties. We hope this work could make us a better understanding of the QDs sensitization mechanism and guide us to explore more QDs-modified nanomaterials with even higher sensing performances.