Improved photocatalytic performance of double-walled TeSi nanotubes: a hybrid density functional calculation†
Abstract
The geometric and electronic structures of TeSi nanotubes were examined using the HSE06 method with Gaussian basis sets. Single-walled (SW) and double-walled (DW) TeSi NTs with (n,n) and (n,n)@(2n,2n) chiralities were investigated for photocatalytic performance. SWNTs exhibit an indirect band gap (∼2.55 eV) and an improved solar-to-hydrogen (STH) conversion efficiency (3.68–4.87%) compared to single-layered TeSi (2.41%). Moreover, strain engineering and heterostructures were used to boost the efficiency of photocatalytic H2O splitting. For strain engineering, our findings indicate that uniaxial strain modifies the band gap, with the band gap of the (30,30) SWNT reaching a 1.72 eV minimum under −5% strain, while the STH conversion efficiency is enhanced through compressive strain. For heterostructure NTs, the STH conversion efficiency was 10.29–15.13%, and the DWNTs showed type II band structure features with smaller band gaps compared to SW ones. Additionally, the larger-diameter DWNTs displayed promising band edge locations for photocatalytic hydrolysis redox potential with pH ranging from 0 to 7. These findings explain the mechanism of the enhanced photocatalytic performance of DWNTs over SWNTs.