Enhanced Water Photolysis with Pt Metal Nanoparticles on Single Crystal TiO₂ Surfaces

Two novel deposition methods were used to synthesize Pt-TiO₂ composite photoelectrodes: a tilt-target room temperature sputtering method and aerosol-chemical vapor deposition (ACVD). Pt nanoparticles (NPs) were sequentially deposited by the tilt-target room temperature sputtering method onto the as-synthesized nanostructured columnar TiO₂ films by ACVD. By varying the sputtering time of Pt deposition, the size of deposited Pt NPs on the TiO₂ film could be precisely controlled. The as-synthesized composite photoelectrodes with different sizes of Pt NPs were characterized by various methods, such as SEM, EDS, TEM, XRD, and UV–vis. The photocurrent measurements revealed that the modification of the TiO₂ surface with Pt NPs improved the photoelectrochemical properties of electrodes. Performance of the Pt-TiO₂ composite photoelectrodes with sparsely deposited 1.15 nm Pt NPs was compared to the pristine TiO₂ photoelectrode with higher saturated photocurrents (7.92 mA/cm² to 9.49 mA/cm²), enhanced photoconversion efficiency (16.2% to 21.2%), and increased fill factor (0.66 to 0.70). For larger size Pt NPs of 3.45 nm, the composite photoelectrode produced a lower photocurrent and reduced conversion efficiency compared to the pristine TiO₂ electrode. However, the surface modification by Pt NPs helped the composite electrode maintain higher fill factor values