γ-GeSe nanotubes: a one-dimensional semiconductor with high carrier mobility potential for photocatalytic water splitting

Abstract

Photocatalytic hydrogen production using solar energy is an effective way to solve the energy crisis nowadays. Inspired by the gamma-GeSe (γ-GeSe) bulk experiment, the HSE06 functional was used to calculate the geometric structure, electronic structure and photocatalytic properties of γ-GeSe single-walled nanotubes. Surprisingly, by cutting γ-GeSe bulk into a slab, the band gap value increased from 0.31 eV to 3.12 eV. In the present work, the structural, electronic, and chemical properties of two types of chirality and different radii γ-GeSe nanotubes have been investigated for the first time. After confirming their stability, we observed that with the increase of the radius, the band gap values of γ-GeSe nanotubes increase gradually, and are generally narrower than that of the slab (where the band gap value of (12,12) nanotubes decreases by 2.65 eV). Remarkably, the hole mobility of γ-GeSe nanotube was 1490 cm² V⁻¹ s⁻¹, while the electron mobility of nanotube was only 489.06 cm² V⁻¹ s⁻¹. Most interestingly, at a certain pH value, the nanotubes with a larger radius could more easily meet the requirement of the water splitting redox potential. All of the evidence confirmed that the γ-GeSe nanotubes (band gap from 1.34 eV to 2.98 eV) could be used as semiconductor photocatalysts used in visible light region. In particular, the tunable band gap of γ-GeSe enables a wide range of light absorption from infrared to ultraviolet light to be achieved, providing ideas for the design of new high-efficiency photocatalysts.