Comparing the photocatalytic activity of TiO2 at macro- and microscopic scales

Antoni Torras-Rosell,Sascha Louring,Svava Daviðsdóttir,Kai Dirscherl,Christian Sloth Jeppesen,Inge Hald Andersen,Sabrina Rostgaard Johannsen

doi:10.1007/s11356-016-7887-3

Abstract

This study focuses on the characterization of photocatalytic TiO2 coatings using Kelvin probe force microscopy. While most photocatalytic experiments are carried out at a macroscopic scale, Kelvin probe force microscopy is a microscopic technique that is surface sensitive. In order to link microscale results to macroscopic experiments, a simple method to establish the relation between Kelvin probe force microscopy and electrochemical measurements is presented by the calibration of a reference sample consisting of epitaxial deposited Cu-Ni-Au that is used as a transfer standard. The photocatalytic properties of TiO2 at macro- and microscopic scales are investigated by comparing photocatalytic degradation of acetone and electrochemical experiments to Kelvin probe force microscopy. The good agreement between the macro- and microscopic experiments suggests that Kelvin probe force microscopy can be a valuable tool towards the understanding, standardization and design of TiO2-based solutions in photocatalytic applications.

Highlights

The benefits of nanomaterials and their contribution to economic growth and job creation have led the European Commission to identify nanotechnology as one of the key enabling technologies (KETs) that constitute a priority for European industrial policy (European Commission 2012a)
SETNanoMetro is a European project within the Seventh Framework Programme (FP7) that aims at determining the properties of titanium dioxide (TiO2) nanoparticles and thin films with various measurement techniques, and establishing a metrological chain of traceability to ensure the reliability of the results
One of the studied properties in SETNanoMetro is the photocatalytic activity of TiO2, which is activated by ultraviolet (UV) light

Summary

Introduction

The benefits of nanomaterials and their contribution to economic growth and job creation have led the European Commission to identify nanotechnology as one of the key enabling technologies (KETs) that constitute a priority for European industrial policy (European Commission 2012a). In this paper, we present a study of the electrical changes on the surface of TiO2 at the microscopic level, when it is exposed to UV light. The first part of this paper (“Kelvin probe force microscopy”) presents KPFM as a microscopic technique, and focuses on establishing a simple calibration procedure between surface potential measurements in KPFM and macroscopic electrochemical measurements based on open circuit potential (OCP).

Results

Conclusion