Evaluation of Au Nanoparticle Catalysts Supported on Metal Oxide for the Catalytic Reduction of 4-NP

4-Nitrophenol (4-NP) pollution in the chemical, dye, and other industries poses significant risks to humans and aquatic organisms. In this study, we prepared metal oxide-supported gold nanoparticles (AuNPs/Al2O3, AuNPs/TiO2, and AuNPs/ZnO) and applied them to the catalytic reduction of 4-NP. The Bader charge and differential charge, dos and d band centers, work function, and reaction free energy of AuNP composites were analyzed through DFT calculations. The influence of metal oxide carriers on the catalytic activity of AuNPs was explored, which decreased in the following order: AuNPs/Al2O3 > AuNPs/TiO2 > AuNPs/ZnO. In addition, the catalytic reduction performance of these AuNP composites for 4-NP in the presence of NaBH4 was investigated. The results showed that the AuNPs/Al2O3 catalyst exhibited the best performance (3.62 ± 0.17 min–1), consistent with the theoretical calculations. Meanwhile, the AuNPs/Al2O3 catalyst exhibited good reusability. More relevantly, the catalytic reduction mechanism of metal oxide-supported AuNPs for 4-NP was proposed from both experimental and theoretical calculations.