Bismuthene, an exfoliated two-dimensional material obtained from bulk bismuth, has drawn significant attention because of its unique electronic properties. Few-layered bismuthene (FLBi) with an average thickness of 1.0 nm was synthesized by the ball mill and sonication method. The FLBi film was fabricated onto a semiconducting SnO₂ electrode by electrophoretic deposition (SnO₂/FLBi). In the flash-photolysis time-resolved microwave conductivity measurement, the SnO₂/FLBi film showed a rise of conductivity upon photoexcitation, supporting the occurrence of the electron injection from the photoexcited FLBi to the conduction band of SnO₂. The SnO₂/FLBi on a transparent fluorine-doped tin oxide (FTO) electrode was used for photoelectrochemical devices. Photocurrents produced by the FTO/SnO₂/FLBi electrode were larger than those produced by the FTO/SnO₂ and FTO/FLBi electrodes because of the efficient electron injection. Moreover, FLBi was noncovalently functionalized with fullerene C₆₀ in a mixed solvent of toluene and acetonitrile. Upon photoexcitation, the composite of FLBi and C₆₀ exclusively led to the occurrence of photoinduced energy transfer from C₆₀ to FLBi without generating the charge-separated state. These results give fundamental insights into the feasibility toward the construction of FLBi-based optoelectronic devices.

Supramolecular composites consisting of fullerene C₆₀ and carbon nanodiamond (ND) were prepared through spontaneous complexation of C₆₀ aggregates onto the surface of ND aggregates in N-methylpyrrolidone. The resultant C₆₀-ND composite was fabricated onto a nanostructured SnO₂ electrode by an electrophoretic deposition method. Formation of the C₆₀-ND composite was supported by dynamic light scattering and field-emission scanning electron microscopy. The C₆₀-ND composite on the SnO₂ electrode revealed high incident photon-to-current efficiencies in the visible region in comparison with the single component system of C₆₀ or ND. The enhanced photocurrent generation of the C₆₀-ND composite may originate from the photoinduced charge separation at the interface between C₆₀ and ND. These results will give important insight into the design of all-nanocarbon optoelectronic devices.

[1] T. Umeyama, Y. Okawada, T. Ohara, and H. Imahori, Chem. Asian J., 14, 4042-4047 (2019).

[2] T. Umeyama, H. Xu, T. Ohara, Y. Tsutsui, S. Seki, H. Imahori, J. Phys. Chem. C, 125, 13954-13962 (2021).