Tuning Redistribution of CuO Nanoparticles on TiO₂ Support

Nanoparticles exhibit unique catalytic performance, depending on their nanoscale size. However, controlling the particle size of the supported catalysts is still challenging. Here, we present a method for tunable redistribution of CuO nanoparticles on rutile TiO₂ support by physically adding pristine TiO₂. The redistribution is driven by the work function difference (WFD) between the TiO₂ support and the TiO₂ additive, both of which exhibit distinct values, as determined through Kelvin probe force microscopy and electron binding energy analysis. Addition of TiO₂ with lower work function (rutile) promotes electron transfer toward the CuO/TiO₂ composite, resulting in nanoparticle aggregation, while addition of TiO₂ with higher work function (anatase) results in smaller CuO on TiO₂. The increase in particle size and electron density of CuO, driven by the addition of rutile TiO₂, promoted the complete conversion of nitrobenzene (100%) within 5 h. This is 2.7 times that of dispersed and degraded CuO driven by mixing with anatase TiO₂ (36.9%).