self-cleaning glass and electrochromic glass universitÀ degli studi di lecce corso di laurea in...

SELF-CLEANING GLASSSELF-CLEANING GLASSandand

ELECTROCHROMIC GLASSELECTROCHROMIC GLASS

UNIVERSITÀ DEGLI STUDI DI LECCECorso di laurea in Ingegneria dei Materiali

A.A. 2001/2002

Scienza e Tecnologia dei Materiali Ceramici

Professore

Dott. Antonio Licciulli

Studente

Daniela Lisi

SELF-CLEANINGSELF-CLEANINGGLASSGLASS

SUMMARYSUMMARY

HISTORY

TITANIUM DIOXIDE

SELF-CLEANING SURFACE

PHOTOCATALYSIS

HYDROPHILICITY

SUPER-HYDROPHILICITY

SELF-CLEANING WINDOWS

HISTORYHISTORY

The late 1960s: the University of Tokyo research photoelettrochemical solar cells. The solid-state photovoltaic device has become the technology of choice.

1972: Fujishima and Honda discovered the

photocatalytic splitting of water on TiO2 electrodes without using

electricity.

1977: Professor Allen J. Bard and co-workers at the

University of Texas first examined the possibilities of using TiO2

to decompose cyanide in water. Many important fundamental

results concerning TiO2 photocatalytic reaction have been

clarified by such intensive works.

The late 1990s: Pilkington, PPG, SSG patent SELF-CLEANING windows.

TITANIUM DIOXIDE TITANIUM DIOXIDE

SELF- CLEANING and ANTIFOGGING functions

PHOTOCATALYST

HYDROPHILIC

RUTILE

Density: 4,2 g/ccRefractive Index: 2,76

ANATASE

Density: 4,2 g/ccRefractive Index: 2,52


White pigment in paints, cosmetics and foodstuffs.

Semiconductor transparent in the visible region of the

spectrum.

Low costs material.

Chemically inert, non-toxic, biocompatible.


SELF-CLEANING SURFACESELF-CLEANING SURFACE

TO CLEAN SURFACE OF BUILDING MATERIALS CAUSES:

Considerable trouble.

High consumption of energy.

Chemical detergents.

High costs

TO REALIZE SELF-CLEANING MATERIAL SURFACES THERE ARE THREE PRINCIPAL WAYS :

Super-hydrophobicity.

Photocatalysis.

Super-hydrophilicity and hydrophilicity

SELF-CLEANING SURFACESELF-CLEANING SURFACE

HYDROPHOBICITYHYDROPHOBICITY

Hydrophobic materials ("water hating") have little or no tendency to adsorb water and water tends to "bead" on their surfaces (i.e., discrete droplets). Hydrophobic materials possess low surface tension values and lack active groups in their surface chemistry for formation of "hydrogen-bonds" with water.

For a given droplet on a solid surface: the contact angle is a measurement of the angle formed between the surface of a solid and the line tangent to the droplet radius from the point of contact with the solid.

CONTACT ANGLE


SUPER-HYDROPHOBICITYSUPER-HYDROPHOBICITY

The LOTUS EFFECT

PHOTOCATALYSIS PHOTOCATALYSIS

The acceleration of the rate of a photoreaction by the presence of a catalyst (semiconductor particle).

WHAT IS IT?

WHAT IS a SEMICONDUCTOR SOLID?

PHOTOCATALYSISPHOTOCATALYSIS

HOW DOES PHOTOCATALYTIC SEMICONDUCTOR WORK?

PHOTOCATALYSISPHOTOCATALYSIS

TiOTiO22 AS PHOTOCATALYST AS PHOTOCATALYST

DhD

AeA

ehhTiO2

HOHhOH2

-

22 OeO

OXIDATION-REDUCTION REACTION ON THE SURFACE OF TIO2


IT IS COMPETITIVE BECAUSE:

A low-cost material is used as photocatalyst.

The reaction is quite fast at mild operating conditions (room temperature, atmospheric pressure).

A wide spectrum of organic contaminants can be

converted to water and CO2.

No chemical reactants must be used and no side reactions are produced.


PRACTICAL APPLICATIONS


HYDROPHILICITYHYDROPHILICITY

Also called hydrophilic, is a characteristic of materials exhibiting an affinity for water. Hydrophilic literally means "water-loving" and such materials readily adsorb water. The surface chemistry allows these materials to be wetted forming a water film or coating on their surface.

HYDROPHILICTYHYDROPHILICTY


MECHANISM OF PHOTO-INDUCED HYDROPHILICITY


a) Upon UV illumination

b) In the dark

TIME DIPENDENCE OF THE WATER CONTACT ANGLE IN AMBIENT ATMOSPHERE


STEP 1STEP 1STEP 2STEP 2STEP 3STEP 3STEP 4STEP 4

SCHEMATIC DIAGRAM OF SUPER-HYDROPHILICITY MECHANISM

SELF-CLEANING WINDOWSSELF-CLEANING WINDOWS


SunClean Glass


Pilkington Activ™

SGG AQUACLEANSGG AQUACLEAN


ELECTROCHROMICELECTROCHROMICGLASSGLASS

SUMMARYSUMMARY

OPTICAL SWITCHING TECHNOLOGY

SMART WINDOWS

THE SOLUTION SageGlass®

OPTICAL SWITCHING TECHNOLOGY OPTICAL SWITCHING TECHNOLOGY

It changes the view of glazing from a FIXED element to a DYNAMIC one.

Optical switching materials can be used for windows where optical and thermal modulation is required.

OPTICAL SWITCHING TECHNOLOGYOPTICAL SWITCHING TECHNOLOGY

to control the flow of light and heat into and out of window, according to an energy management scheme.

THE PURPOSE IS:


a large change in optical properties upon a change in either light intensity, spectral composition, heat, electrical field, or injected charge.

THE BASIC PROPERTY IS:


This optical change results in a transformation from highly transmitting state to a partly reflecting or absorbing state, either totally or partly over the solar spectrum.


SMART WINDOWS SMART WINDOWS

Electrochromic windows change the light transmittance, transparency, or shading of windows in response to an environmental signal.

SMART WINDOWSSMART WINDOWS

HOW ECDs WORK?

A voltage applied across the transparent conducting oxide layers causes hydrogen or lithium anions (A+) to be injected into the electrochromic layers.


HOW ECDs ARE MADE?


ELECTROCHROMIC MATERIAL PERFORMANCE OBJECTIVES ARE:

continuous range in solar and optical transmittance, reflectance, and absorbance between bleached and coloured states;

contrast ratio (CR) of at least 5 a 1;

colouring and bleaching times (switching speed) of a few minutes;

switching with applied voltages of 1–5 V;

acceptable neutral colour;

large area with excellent optical clarity;

sustained performance over 20–30 yr;

acceptable cost ($100/m2);


GLASS/ITO/NiO/Inorganic Electrolyte/WO3/ITO/GLASS

Li) H, (M blue) (deep3

WOx

MxMxe(clear)3

WO

- xe (gray)x

NiO(OH)xOH(clear) NiO


GLASS/ITO/NiO/Inorganic Electrolyte/WO3/ITO/GLASS


GLASS/ITO/PANI/PB/PAMPS/WO3/ITO/GLASS


ECDs as ENERGY SOURCE

THE SOLUTION THE SOLUTION SageGlass®SageGlass®

THE SOLUTION - SageGlass®THE SOLUTION - SageGlass®

self-cleaning glass and electrochromic glass universitÀ degli studi di lecce corso di laurea in...

Documents

photocatalysis slide

photocatalyst slide

selfcleaning glass slide

titanium dioxide slide

surface of tio

lotus effect slide

solid surface

surface chemistry