Construction of a MoO[sub.x]/MoS[sub.2] Heterojunction via the Surface Sulfurization of the Oxide and Its Photocurrent-Switching Characteristics in the Range of the Broadband Light Spectrum

• Published in: Materials 2024-11, Vol.17 (22)
• Main Authors: Ma, Xingfa, Zhang, Xintao, Gao, Mingjun, Wang, You, Li, Guang
• Format: Article
• Language: English
• Subjects: Electric fields; Oxides; Sulfur compounds
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma17225507

In order to utilize the longer wavelength light, the surface sulfurization of MoO[sub.3] was carried out. The photocurrent responses to typical 650, 808, 980, and 1064 nm light sources with Au gap electrodes were investigated. The results showed that the surface S–O exchange of MoO[sub.3] improved the interfacial charge transfer in the range of the broadband light spectrum. The S and O can be exchanged on the surface of MoO[sub.3] nanosheets under the hydrothermal condition, leading to the formation of a surface MoO[sub.x]/MoS[sub.2] heterojunction. The interfacial interaction between the MoO[sub.3] nanosheets and MoS[sub.2] easily generated free electrons and holes, and it effectively avoided the recombination of photogenerated carriers. Meanwhile, the surface S-doping of MoO[sub.3] also resulted in the generation of an oxygen vacancy and sulfur vacancy on MoO[sub.3−x]S[sub.2−y]. The plasmonic characteristics of MoO[sub.3−x] contributed to the enhancement of the interfacial charge transfer by photoexcitation. Otherwise, even with zero bias applied, a good photoelectric signal was still obtained with polyimide film substrates and carbon electrodes. This indicates that the formation of the heterojunction generates a strong built-in electric field that drives the photogenerated carrier transport, which can be self-powered. This study provides a simple and low-cost method for the surface functionalization of some metal oxides with a wide bandgap.