P-n heterojunction photocatalyst, air purifier including the same, and method of preparing the p-n heterojunction photocatalyst
A p-n heterojunction photocatalyst, an air purifier including the p-n heterojunction photocatalyst, and a method of preparing the p-n heterojunction photocatalyst. The p-n heterojunction photocatalyst includes a granule type composite which includes: first compound particles; and second compound particles on at least a portion of surfaces of the first compound particles, wherein the composite has a size of about 0.9 μm to about μm based on a major axis, a standard deviation of the size is about ±0.9 μm or less, and upon exposure to energy irradiation, the composite generates a reactive oxygen species of singlet oxygen ( 1 O 2 ) to induce photolysis of gaseous pollutants.
1 . A p-n heterojunction photocatalyst comprising a composite, the composite comprising:
an agglomeration of a plurality of primary particles to provide a secondary first compound particles, wherein the particle size of the primary particles is in a range of about 20 nanometers to about 30 nanometers based on a major axis; and
second compound particles on at least a portion of surfaces of the secondary first compound particle wherein the particle size of the secondary first compound particle is in a range of about 0.9 micrometers to about 5 micrometers based on a major axis, a standard deviation of the size is about ±0.9 micrometers or less, and upon exposure to energy irradiation, the composite generates a reactive oxygen species of singlet oxygen ( 1 O 2 ) to induce photolysis of gaseous pollutants.
2 . The p-n heterojunction photocatalyst of claim 1 , wherein the secondary first compound particle is an n-type compound, and the second compound particles are a p-type compound.
3 . The p-n heterojunction photocatalyst of claim 1 , wherein the secondary first compound particles comprises TiO 2 , BiVO 4 , ZnO, WO 3 , CdS, BaTiO 3 , or a combination thereof.
4 . The p-n heterojunction photocatalyst of claim 1 , wherein the second compound particles comprise BiOI, Cu 2 O, CuO, NiO, BiFeO 3 , LaFeO 3 , GaP, or a combination thereof.
5 . The p-n heterojunction photocatalyst of claim 1 , wherein the second compound particles have an OH generation oxidation potential of about 1.97 V or less (vs NH-S) in a valence band.
6 . The p-n heterojunction photocatalyst of claim 1 , wherein the surfaces of the secondary first compound particle is negatively charged, and the second compound particles are positively charged and are self-assembled on the negatively charged surfaces of the secondary first compound particle through an electronic interaction to provide a granular composite.
7 . The p-n heterojunction photocatalyst of claim 1 , wherein the composite exhibits photolysis activity in an ultraviolet wavelength region.
8 . The p-n heterojunction photocatalyst of claim 1 , wherein the composite comprises titanium, and a peak of Ti2p binding energy, as measured by X-ray photoemission spectroscopy (NIPS), is shifted in a positive direction with respect to a peak of Ti2p binding energy of a TiO 2 photocatalyst.
9 . The p-n heterojunction photocatalyst of claim 1 , wherein the composite comprises bismuth, and a peak of Bi4f binding energy as measured by NIPS is shifted in a negative direction with respect to a peak of Bi4f binding energy of a TiO 2 photocatalyst.
10 . The p-n heterojunction photocatalyst of claim 1 , wherein a content of the plurality of primary particles is in a range of about 50 weight percent to about 95 weight percent, and a content of the second compound particles is in a range of about 5 weight percent to about 50 weight percent, based on a total weight of the composite.
11 . An air purifier comprising a photocatalyst filter, the filter comprising the p-n heterojunction photocatalyst of claim 1 .
12 . A method of preparing the p-n heterojunction photocatalyst according to claim 1 the method comprising:
adding a plurality of primary compound particles to one or more second compound precursor solutions to obtain a mixture, wherein the particle size of the primary particles is in a range of about 20 nanometers to about 30 nanometers based on a major axis; and drying the mixture to prepare a composite comprising the agglomeration of the plurality of primary particles to provide the secondary first compound particles and the second compound particles on at least the portion of the surface of secondary first compound particle, wherein the composite has a size of about 1 micrometer to about 5 micrometers based on a major axis, a standard deviation of the size is about ±0.9 micrometers or less, and upon exposure to energy irradiation, the composite generates a reactive oxygen species of singlet oxygen ( 1 O 2 ) to induce photolysis of gaseous pollutants.
13 . The method of claim 12 , wherein the second compound precursor comprises Bi(NO 3 ) 3 , Bi(COOCH 3 ) 3 , KI, Fe(NO 3 ) 3 , La(NO 3 ) 3 , FeSO 4 , La 2 (CO 3 ) 2 (OH) 2 , Fe 2 O 3 , a hydrate thereof, or a combination thereof.
14 . The method of claim 12 , wherein the secondary first compound particles comprise TiO 2 , BiVO 4 , ZnO, WO 3 , CdS, BaTiO 3 , or a combination thereof.
15 . The method of claim 12 , wherein the adding the plurality of primary compound particles to the one or more second compound precursor solutions provide a content of the second compound particles in a range of about 5 weight percent to about 50 weight percent based on a total weight of the composite.
16 . The method of claim 12 , wherein the drying of the mixture is performed for about 12 hours to about 30 hours at a temperature of about 60° C. to about 100° C. under vacuum.