DOI: https://doi.org/10.55373/mjchem.v27i3.190

Keywords: Cerium oxide (CeO₂); gold (Au); deposition-precipitation; p-nitrophenol (p-NP)

Abstract

The reduction of p-nitrophenol (p-NP) is widely used as a model reaction to evaluate catalytic activity. In this study, cerium oxide (CeO₂) supports were synthesized via two simple methods: chemical precipitation (method A) and co-precipitation (method B). Gold (Au) nanoparticles were subsequently deposited onto CeO₂ supports using the deposition-precipitation (DP) technique. The CeO₂ supports were prepared by reacting cerium nitrate with ammonia solution (method A) and potassium carbonate (method B), producing cerium oxide particles. The resulting particles were characterized using Fourier Transform Infrared (FTIR) spectroscopy. FTIR analysis revealed prominent peaks in the range of 3300–2800 cm^-1, corresponding to O-H stretching in CeO₂-A and CeO₂-B. X-ray diffraction (XRD) analysis confirmed the cubic fluorite structure of cerium oxide in both samples (JCPDS No. 01-075-0076). Meanwhile, the FTIR spectra of Au-CeO₂-A and Au-CeO₂-B demonstrated successful Au immobilization, as evidenced by shifts in the support’s characteristic peaks. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) confirms the presence of Au, with loadings of 0.565 wt% in Au-CeO₂-A and 0.465 wt% in Au-CeO₂-B, respectively. The Au-CeO₂ catalysts achieved 100% conversion of p-NP to p-aminophenol, with a rate constant (k) of 5.78 x 10^-4 s^-1 for Au-CeO₂-A and 4.37 x 10^-4 s^-1 for Au-CeO₂-B.