Preparation of mesoporous TiO2–C composites as an advanced Ni catalyst support for reduction of 4-nitrophenol

Abstract

To overcome the aggregation and recovery problems and regulate the electronic and chemical properties of Ni nanoparticle catalysts, ordered mesoporous TiO₂–C composites have been designed and synthesized as an advanced support, combined with the in situ loading and reduction of Ni nanoparticles via a multi-component co-assembly method. The resulting mesoporous Ni/TiO₂–C composites exhibit a large surface area (∼340 m² g⁻¹), uniform pore size (∼4 nm), moderate pore volume (∼0.23 cm³ g⁻¹), and magnetic saturation value of ∼5.1 emu g⁻¹. The corresponding Ni content was varied in the range from 2 to 13 wt%. More importantly, the mesoporous Ni/TiO₂–C composites display high catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol with NaBH₄. The maximum pseudo-first-order reaction rate constant that was obtained with mesoporous Ni/TiO₂–C composites (13 wt% Ni) was calculated to be ∼0.40 min⁻¹, which is much higher than that with Ni/C, TiO₂–C and Ni/TiO₂ composites. In addition, these catalysts were found to be stable for a long time and reusable several times.