Secondary growth of hierarchical nanostructures composed only of Nb3O7F single-crystalline nanorods as a new photocatalyst for hydrogen production

Abstract

Development of efficient photocatalysts for hydrogen (H₂) production from water splitting is highly sought for the current sustainable energy issue. This paper has demonstrated a one-pot hydrothermal approach for the preparation of hierarchical nanostructures (HNs) composed only of Nb₃O₇F single-crystalline nanorods by using H₂NbF₇ as a precursor and 2-propanol as a selective adsorption agent. In our protocol, modulating the hydrolysis rate of the coordination complex H₂NbF₇via simply controlling its concentration not only produces Nb₃O₇F single crystalline nanorods by the restrictive growth on [110] due to the selective adsorption of 2-propanol on the sidewalls, but also leads to secondary nucleation for the growth of new nanorods on the pre-formed ones, leading to the formation of Nb₃O₇F HNs. The resultant Nb₃O₇F HNs strongly respond to ultraviolet light and have a band gap of 3.22 eV as well as the conducting band minimum at −0.44 eV. They exhibit excellent photocatalytic H₂ production activity with a good recycling stability when 0.5 wt% Pt is used as a cocatalyst. The H₂ production rate reaches 830 µmol h⁻¹ g⁻¹, about 23.7 and 5.7 times higher than that of Nb₂O₅ sphere-shaped micro-particles and commercial Nb₂O₅ nanoparticles, respectively. Furthermore, they can also show notable photocatalytic H₂ production activity even without any cocatalysts. This suggests that the resultant Nb₃O₇F HNs are promising as a new photocatalyst for H₂ production.