UV Blocking Glass: Low Cost Filters for Visible Light Photocatalytic Assessment

Charles W Dunnill

doi:10.1155/2014/407027

Abstract

A number of commercially available art protection products have been compared and assessed for their suitability as UV blocking filters in the application of “visible light” photocatalytic research. Many groups claiming visible light photocatalytic success employ filters to block out stray UV radiation in order to justify that their photocatalysts are indeed visible light photocatalysts and not UV light photocatalysts. These filters come in varying degrees of ability and price and many authors fail to correctly characterise their filters in individual papers. The use of effective filters to prevent both false positive and false negative results is important to maintain scientific rigor and create accurate understanding of the subject. The optimum UV filter would have the highest UV blocking properties (<390 nm) and simultaneously the highest visible light transmission (390–750 nm). Single and double layers of each of the glass products were assessed as well as laminate products. The conclusions show an inexpensive and highly effective setup for the conduction of visible light photochemistry that should be incorporated as a standard part in any researcher’s work where the claim of visible light activity is made.

Highlights

With current advances in visible light photocatalysis taking an increasing limelight in scientific publications there is an escalating importance in the need to accurately prove the presence of “visible light” induced photocatalysis as opposed to photocatalysis that occurs as a result of stray photons of high energy from a visible light source
Delamination of the phosphor leaves holes through which the UV light can escape. This leaking UV light can lead to false positive claims of visible light photocatalysts [1]
The UV-visible spectrum for the single thickness and double thickness of each of the samples is shown in Figure 1, alongside the hypothetical optimised trace

Summary

Introduction

With current advances in visible light photocatalysis taking an increasing limelight in scientific publications there is an escalating importance in the need to accurately prove the presence of “visible light” induced photocatalysis as opposed to photocatalysis that occurs as a result of stray photons of high energy from a visible light source. It has been observed that the visible light sources often get better with age. They especially improve in effectiveness when dropped (without breaking) or handled roughly. This was explained by virtue of the fact that use and time lead to the delamination of the phosphor coating on the inside of the bulb and the inefficient conversion of high energy emitted radiation into visible wavelength light. Delamination of the phosphor leaves holes through which the UV light can escape This leaking UV light can lead to false positive claims of visible light photocatalysts [1]. Leakage of >750 nm light is not an issue for obvious reasons; leakage of even a tiny amount of

Methods

Results

Conclusion