Self-organized TiO_2 nanotube arrays with uniform platinum nanoparticles for highly efficient water splitting

摘要

Highly efficient water splitting electrode based on uniform platinum (Pt) nanoparticles on self-organized TiO_2 nanotube arrays (TNTAs) was prepared by a combination of multi-step electrochemical anodization with facile photoreduction process. Uniform platinum (Pt) nanoparticles with an average diameter of 8 nm are distributed homogeneously on nanoporous top layer and underneath TiO_2 nanotube wall. In comparison to pristine TNTAs, Pt@TNTAs show substantially enhanced photocurrent density and the incident photon-to-current conversion efficiency (IPCE) in the entire wavelength window. The maximum photocurrent density and IPCE from the optimized Pt®TNTAs photoelectrode (Pt, -1.57 wt%) were about 24.2 mA cm~(-2) and 87.9% at 350 nm, which is much higher than that of the pure nanotubes sample (16.3 mA cm~(-2) and 67.3%). The resultant Pt@TNTAs architecture exhibited significantly enhanced photoelectrochemical activities for solar water splitting with hydrogen evolution rate up to 495 nmol h~(-1) cm~(-2) in 2 M Na_2CO_3 + 0.5 M ethylene glycol under the optimal external bias of -0.3 V_(SCE).