Highly broadband plasmonic Pt nanoparticles modified a-Fe2O3/TiO2 nanotubes for efficient photoelectrochemical water splitting

In order to develop an efficient photocatalyst electrode for water splitting and solar energy harvesting in the visible region, TiO2 nanotubes arrays (TiNT) modified by hematite (& alpha;-Fe2O3) and broadband plasmonic platinum (Pt) nanoparticles have been successfully synthesized via electrochemical anodization and electrodeposition methods. & alpha;-Fe2O3 and Pt nanoparticles were electrodeposited on TiNT at different durations, namely 25, 50 and 100s.Interestingly, compared with pure TiNT, important improvement in photocurrent densities and photoconversion efficiencies were found. The optimal Pt nanoparticle size (50-90 nm), achieved at a deposition time of 50s, resulted in a stronger visible light absorption and much higher photocurrent. Pt(50s)/TiNT photoelectrode reached photocurrent density value of 2.3 mA/cm2 at 1.23 V vs. RHE, which is more than 100 times that of pristine TiNT. An impressive maximum photoconversion efficiency of about 10% was reached by Pt/ & alpha;-Fe2O3/TiNT photoelectrode. The improved photoelectrochemical activity of the photoelectrode can be ascribed to the better absorption of visible light due to the presence of optimally sized Pt nanoparticles with surface plasmon resonance effect (SPR) and more efficient charge separation/transport owing to the presence of & alpha;-Fe2O3/TiNT heterojunction.