Electrostatically Directed Assembly of Nanostructured Composites for Enhanced Photocatalysis

Abstract It is well established that the activity of photocatalysts can be improved by deposition of redox catalysts, which can effectively extract the photogenerated charge carriers, enhance the rate of interfacial reactions, and thus suppress undesired recombination processes. For optimum performance, a high degree of control over the loading, size, and surface catalytic properties of redox catalyst particles is desirable. Herein, a novel, highly controllable, and versatile method for preparation of TiO 2 catalyst composites is reported. It starts with the generation of “naked” (ligand‐free) nanoparticles of CuO x or FeO x by pulsed laser ablation of metal oxide targets in water. In the next step, a nearly quantitative colloidal deposition of CuO x and FeO x nanoparticles onto anatase TiO 2 substrate is achieved by adjusting the pH in order to establish electrostatic attraction between the colloids and the substrate. The resulting TiO 2 –CuO x and TiO 2 –FeO x assemblies with optimum catalyst amount (≈0.5 wt%) exhibit photocatalytic rates in degradation of 2,4‐dichlorophenoxyacetic acid enhanced by a factor of ≈1.5 as compared to pristine TiO 2 under simulated solar irradiation. The electrostatically directed assembly of TiO 2 with ligand‐free catalyst nanoparticles generated by pulsed laser ablation is thus demonstrated as a viable tool for preparation of composites with enhanced photocatalytic performance.