Cu/Ni nanoparticles supported on TiO2(B) nanotubes as hydrogen generation photocatalysts via hydrolysis of ammonia borane

Abstract

TiO₂(B) nanotubes (NTs) were used as carriers to support metal Cu/Ni nanoparticles for the catalytic hydrolysis of ammonia borane (NH₃BH₃, AB) under visible light. The TiO₂ NTs were first prepared by the hydrothermal method and subsequently loaded with Cu/Ni metal nanoparticles by the impregnation reduction method. The structure, morphology, and chemical composition of the as-obtained catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), inductively coupled plasma emission spectroscopy (ICP), and ultraviolet–visible spectroscopy (UV-Vis). The characterization results revealed that the metal nanoparticles were uniformly loaded on the surface of the TiO₂ NTs, while the band gap of the catalyst was reduced significantly from 3.22 to 2.68 eV. The catalysts showed an excellent photocatalytic performance towards the hydrolysis of AB for H₂ production. Thus, the H₂ production rate of Cu_0.64Ni_0.36-TiO₂ NTs reached 5763.86 mL g⁻¹ min⁻¹, with a total turnover frequency (TOF) of 15.90 mol H₂ (mol cat)⁻¹ min⁻¹ for a loading volume of metal particles of 5.25 wt%. The results presented herein demonstrate that TiO₂(B) can be a potential photocatalyst for effective H₂ production, and also provide a cheap and effective approach to improve the light-to-H₂ energy conversion.