Kanta Mori graduated from the College of Engineering Sciences, University of Tsukuba. Since 2026 he has been pursuing M.Eng. in Kondo-Oki laboratory, Graduate School of Science and Technology, University of Tsukuba. His research focuses on the development of electrocatalytic materials for water electrolysis, particularly boron-based materials for the oxygen evolution reaction.

Rhombohedral boron monosulfide (r-BS) is a layered material reported to exhibit high oxygen evolution reaction (OER) activity.[1, 2] Theoretical studies indicate that p-type doping may further enhance its catalytic performance by promoting hole-dominant semiconducting behavior.[3] In this study, phosphorus incorporation was examined as a strategy to tune the electronic structure of r-BS and improve its OER activity. Phosphorus-incorporated r-BS samples containing 1, 3, 5, and 10 mol% P were synthesized under high-pressure and high-temperature conditions (5.5 GPa, 1873 K), while maintaining the overall composition B:(S+P)=1:1. Powder X-ray diffraction (XRD) suggested expanded interlayer spacing and changes in lattice distortion and bond strength (Fig. 1). UV-Vis spectroscopy showed enhanced absorbance in the visible region and a reduced optical bandgap (Fig. 2). These results indicate that phosphorus incorporation modifies the structural and electronic properties of r-BS, which may influence its electrocatalytic performance toward OER.

1. L. Li, et al., Chem. Eng. J. 471, 144489 (2023). DOI: 10.1039/D4TA0220XX
2. H. Kusaka, et al., J. Mater. Chem. A 9, 24631 (2021). DOI: 10.1039/D4TA022XXX
3. S. Hagiwara, et al., ACS Appl. Mater. Interfaces 15, 50174 (2023). DOI: 10.1039/D4TA0220XX