Vertically aligned nitrogen doped (Sn,Nb)O2 nanotubes – Robust photoanodes for hydrogen generation by photoelectrochemical water splitting

Hydrogen generation from photoelectrochemical (PEC) water splitting is on the forefront of clean energy generation landscape. The efficiency of PEC system is dependent on the engineering of semiconductors with tailored narrow band gap coupled with superior photoelectrochemical activity and desired stability vital for the commercialization of PEC water splitting cells. We report herein the study of vertically aligned Nb and N doped SnO2 nanotubes (NTs), i.e., (Sn0.95Nb0.05)O2:N NTs for PEC water splitting. (Sn0.95Nb0.05)O2 NTs was selected for co-doping with nitrogen by systematic analysis of applied bias photon-to-current efficiency of various Nb doped SnO2 (x = 0–0.1) compositions. Consequently, excellent photoelectrochemical stability and the highest efficiency of 4.1% is obtained for (Sn0.95Nb0.05)O2:N-600 NTs never observed for other known TiO2, ZnO, and Fe2O3 systems to date. Additionally, theoretical first principles study provides understanding of Nb and N co-doping on the electronic structure and band gap of SnO2 semiconductor, further corroborating results of the experimental study.