Ar+-ion Bombardment of TiO2 Nanotubes Creates Co-catalytic Effect for Photocatalytic Open Circuit Hydrogen Evolution

TL;DR

This study demonstrates that argon ion bombardment creates sub-oxide states in TiO2 nanotubes, significantly enhancing their photocatalytic hydrogen evolution without noble metal decoration, indicating a new co-catalytic mechanism.

Contribution

It introduces a novel method of using argon ion bombardment to activate TiO2 nanotubes as effective co-catalysts for hydrogen evolution.

Findings

Enhanced H2 evolution under UV and AM1.5 conditions

Sub-oxide states correlate with increased catalytic activity

No noble metal decoration needed for activation

Abstract

In the present work, extended Argon ion bombardment was used to modify anatase TiO2 nanotube (NTs) layers. In situ X-ray photoelectron spectroscopy revealed a high content of sub-oxide formed (Ti3+, Ti2+ states) in the nanotube layers. These samples were tested for their ability to show open-circuit photocatalytic hydrogen evolution. We found for UV (cw laser 325nm) illumination as well as for AM1.5 conditions, a strongly enhanced H2 evolution activity in absence of the usual noble metal-nanoparticle decoration. We conclude therefore that these sub-oxide states can play an important role in the activation of TiO2 nanotubes - namely as a H2 evolution co-catalyst.