P-n heterojunction photocatalyst, air purifier including the same, and method of preparing the p-n heterojunction photocatalyst

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 (1O2) to induce photolysis of gaseous pollutants.