Metal chalcogenides are widely used, e.g., in electronic or catalytic applications. The properties of these compounds can be strongly influenced by their crystal structures and porosity. Bismuth selenide (Bi₂Se₃), for example, is a semiconducting material with a narrow bandgap that has possible uses in optoelectronics, sensors, catalysis, etc. However, the effects of a porous structure on the properties of Bi₂Se₃ are not well-studied.

Minsu Han, The University of Queensland, Brisbane, Australia, Yusuke Yamauchi, The University of Queensland and Nagoya University, Japan, and colleagues have prepared mesoporous semiconductive Bi₂Se₃ films with uniformly sized mesopores and investigated the structural and charge-transport properties of the materials. The synthesis was based on a soft-templating method. The team used micelles of a polystyrene-block-poly(ethylene oxide) (PS-b-PEO) block copolymer in a mixed solvent composed of water and tetrahydrofuran (THF) as templates during the electrodeposition of Bi₂Se₃ films on conductive substrates. The micelles interact with the Se and Bi precursors in solution and ensure that mesopores are formed during deposition. The sizes of the pores could be tuned by changing the molecular weight of the polymer; in this work, mesopores with uniform sizes of either 9 nm or 17 nm were formed.

The researchers found that the mesoporous Bi₂Se₃ films have significantly larger electrochemically active surface areas than a comparable nonporous film. The charge transport through the Bi₂Se₃ surface can be changed by controlling the pore structure and surface area. Films with optimized charge transport could be promising for different kinds of applications.

• Mesoporous Semiconductive Bi₂Se₃ Films,
  Tomota Nagaura, Aditya Ashok, Azhar Alowasheeir, Arya Vasanth, Minsu Han, Yusuke Yamauchi,
  Nano Lett. 2023.
  https://doi.org/10.1021/acs.nanolett.3c00183