It is known that titanium oxide can decompose water with ultraviolet rays.
This is the source of discovery of Honda Fujishima effect.
Titanium oxide is used as a photocatalyst by decomposing organic matter to keep the coated surface clean.
Why can titanium oxide decompose organic matter at this time? What?
This is also considered from the ionization tendency and redox potential.
The following is a quote from my blog.
The greater the difference in ionization tendency is, the stronger the reducing property is.
The strontium / tantalum oxide having less bismuth is easily oxidized, and the reducing property is strong.
If added to SrBi 2 Ta 2 O 9,
Li (s), E ° = -3.045 V
Ba (s), E ° = -2.92 V
Sr (s), E ° = -2.89 V
Al (s), E ° = -1.676 V
Ti, E ° = -1.63 V [3]
Zr, E ° = -1.534 V [3]
Mn (s), E ° = -1.18 V
Ta (s) + 5 H 2 O, E ° = - 0.81 V
Fe (s), E ° = - 0.44 V
Pb (s), E ° = - 0.1263 V
H 2 (g), E ° = 0 V
Sb (s) + 3 H 2 O, E ° = 0.1504 V
Bi (s), E ° = 0.3172 V
Cu (s), E ° = 0.340 V
SBTO is expected to be E __ = -0.4 to -0.6 V.
Although E ゜ = 0 V hydrogen is not reduced,
E ° = - 0.9 V Strontium · Tantalum oxide reduces the surface to bismuth metal.
In the mechanism, hydrogen becomes a hydrogen ion with a platinum electrode.
Hydrogen ions first reduce strontium tantalum oxide.
Reduce the BLSF crystal that is in contact with the oxygen-deficient form of the resulting strontium-tantalum oxide.
The surface reduced from BLSF shows electrical conductivity.
The oxidation-reduction potential of titanium can be estimated to be -1.63 V.
Beyond this potential, titanium is reduced by light,
The property of reducing opponent and trying to return to titanium oxide,
I think that it is the essence of reducing and decomposing organic matter.
Apart from titanium, near potentials are zirconium, manganese, tantalum.
For these to work as a photocatalyst,
First, it is decomposed by light,
Does it have the property of returning itself to oxides by reducing around them shortly afterwards? That is the deciding factor.
When quoted,
””””
Visible light responsive photocatalyst, method for producing the same, and method of using same
PROBLEM TO BE SOLVED To develop a visible light responsive photocatalyst having sensitivity to any visible light region such as an incandescent lamp, white LED, sun natural light and the like and having activity for photolysis of water.
SOLUTION: This photocatalyst mainly composed of zirconium oxide and graphite or graphite silica exhibits water decomposition performance of quantum yield of 30% or more even in a visible light region containing almost no ultraviolet light of 60 to 100 W incandescent lamp photocatalyst.
DETAILED DESCRIPTION OF THE INVENTION
【Technical field】
[0001]
TECHNICAL FIELD The present invention relates to a visible light responsive photocatalyst, a method of manufacturing the same, and a method of using the same.
BACKGROUND ART
[0002]
As a photocatalyst having visible light activity, titanium oxide-based ones are dominant (for example, JP-A Nos. 2003-260370, 2004-330074, 11-333302, and 11-333304).
[0003]
On the other hand, zirconium oxide is said to have a large hand cap and can not respond to visible light, but also with respect to those using this, as described in JP-A-2009-106897, JP-A-2003-117407, JP-A-2007-75678 And so on.
[0004]
Of these, JP-A-2009-106897 discloses a visible light responsive photocatalyst in which tungsten oxide particles of 0.05 μm or less are adhered to the surface of a white pigment such as titanium oxide or zirconium oxide with respect to zirconium oxide.
[0005]
In addition, JP 2007-75678 discloses a visible light sensitive functional oxide containing niobium, tantalum, or antimony, Cr, Fe or the like in zirconium oxide.
””””
As described above, besides titanium, zirconium, manganese, and tantalum can also be photocatalysts at close potential.
These metals show the effect of decomposing organic substances with reducing power.
I'm watching these are also involved in redox at the crystal grain interface.
When the reduction of the crystal grain interface occurs,
The topological insulator of the Nobel Prize in Physics is formed.
By irradiating ultraviolet rays on the material combined with bismuth and photocatalyst,
Microscopic reduction occurs,
I believe that the surface of the insulating crystal is reduced to show conductivity, which is also the expression mechanism of the topological insulator.
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