AuPd bimetallic nanoparticle decorated TiO2 rutile nanorod arrays for enhanced photoelectrochemical water splitting

摘要

Here, the synthesis of TiO2 rutile nanorod arrays (TiO2 NRs) decorated with bimetallic gold-palladium cocatalyst nanoparticles (AuPd NPs) is described. The modified photoelectrode was characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and electrochemical impedance spectroscopy (EIS). AuPd-TiO2 NRs (AuPd-TiO2) demonstrate high photocatalytic activity for photoelectrochemical (PEC) water splitting. The tailored structure of AuPd-TiO2 depicts a boosted photocurrent of 3.36 mA cm(-2) under AM 1.5 illumination (100 mW cm(-2)) and efficiency of 2.31% at a low-voltage bias of 0.28 V vs. Ag-AgCl. EIS and Mott-Schottky plots reveal that AuPd-TiO2 has the lowest charge transfer resistance and highest carrier density which suggest a faster carrier transfer. These results indicate that AuPd NPs inherit both properties of light sensitizer from Au and faster electrocatalytic activity of Pd, thus not only generating hot electrons due to the surface plasmonic effect but also facilitating transfer of these electrons to the TiO2 NRs because of high electrocatalytic activity. Moreover, AuPd NPs contribute to the overall enhancement of PEC performance by producing a Schottky barrier, hindering electron-hole recombination and passivating surface defects/traps of TiO2 NRs which eventually enhances the photocurrent significantly.