Architectural effects of Au-Pd nanoparticles on the reduction efficiency of 4-nitrophenol

Supported metal nanoparticles are widely used as heterogeneous catalysts, whose catalytic performance is governed not only by metal composition but also by nanoparticle architecture. Herein, a sol-immobilization strategy was employed to achieve the controlled construction of bimetallic Au-Pd nanoparticles supported on TiO₂, including nanosized (3.2-5.6 nm) alloyed Au_xPd_y nanoparticles as well as core-shell architectures (Au@Pd and Pd@Au). NaBH₄-assisted reduction of 4-nitrophenol (4-NP) was selected as a model reaction to explore structure-activity relationships of nanoparticle-based catalysts under well-defined conditions. By maintaining comparable particle sizes and metal loadings, a systematic comparison of structural effects was enabled. The results demonstrate that the catalytic performance of Au-Pd nanoparticles is strongly influenced by the spatial distribution of Pd within the nanoparticles, highlighting the critical role of atomic architecture in governing the apparent activity of bimetallic catalysts in a model surface-mediated reductive transformation.