Selective Design of Mesoporous BiSe Films with Orthorhombic and Rhombohedral Crystals.

Materials with the same chemical composition can exhibit distinct properties depending on their crystal phases. Here, the synthesis of two types of mesoporous BiSe films at different reduction potentials is reported and their application in electrochemical glucose sensing. Mesoporous BiSe is synthesized by incorporating block copolymer micelle assemblies into the deposition solution and applying a reduction potential. To characterize the crystal phases accurately, BiSe films are heat-treated at 200 °C for 1 h in a nitrogen atmosphere. The results reveal that the BiSe films synthesized under different conditions exhibit clearly distinct phases: rhombohedral (R-BiSe) and orthorhombic (O-BiSe). The R-BiSe-8 nm, featuring 8 nm pores and synthesized at a more negative reduction potential, outperforms its nonporous counterpart, achieving a glucose sensing sensitivity of 0.143 µA cm µM and a detection limit of 6.2 µM at pH 7.4 in 0.1 M phosphate-buffered saline solution. In contrast, the O-BiSe, prepared at a relatively positive potential, exhibits no glucose-sensing activity. The inactivity of O-BiSe for glucose oxidation is likely due to the energetically unfavorable intermediates, as predicted by density functional theory calculations. These findings underscore the critical role of crystal phase control in porous nanomaterials and pave the way for developing innovative porous systems.