Bismuth Oxychalcogenide Nanosheet: Facile Synthesis, Characterization, and Photodetector Application

Abstract New 2D bismuth oxychalcogenide nanosheets have excellent theoretical properties such as high electronic mobility and excellent oxidation resistance, which have good application prospective for optoelectronic devices. In this paper, during the synthesis process via mild hydrothermal route, ammonium bismuth citrate (C 6 H 13 BiN 2 O 7 ·H 2 O) is selected as Bi source. Both Bi 2 O 2 S and Bi 2 O 2 Se nanosheets (lateral size: over 2.0 µm, thickness: ≈ 5.0 nm) are synthesized successfully using thiourea (CH 4 N 2 S) as S source, and sodium selenite (Na 2 O 3 Se) as Se source, respectively. The as‐synthesized Bi 2 O 2 S and Bi 2 O 2 Se materials have desirable nanosheet‐like morphologies. After adding C 6 H 13 BiN 2 O 7 ·H 2 O, [(NH 3 ) 2 C 6 H 7 O 7 ] 3 ‐ can intercalate between the interlayers of Bi 2 O 2 S or Bi 2 O 2 Se, limiting the growth along c ‐axis direction, so that 2D sheets can be obtained. Finally, the photodetectors are fabricated based on Bi 2 O 2 S and Bi 2 O 2 Se films coated by thermal spraying. The experimental results show that the maximum responsivity and detectivity of Bi 2 O 2 S‐based photodetector are 0.059 A W ‐1 and 6.77 × 10 9 Jones, respectively. As to Bi 2 O 2 Se‐based photodetector, the maximum responsivity and detectivity can reach 75.14 A W ‐1 and 3.95 × 10 12 Jones, respectively. The mild hydrothermal synthesis using ammonium bismuth citrate as Bi source is a universal and facile method to obtain Bi 2 O 2 S and Bi 2 O 2 Se nanosheets for optoelectronic applications.