Improved photocatalytic performance of double-walled TeSi nanotubes: a hybrid density functional calculation

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.