Metatitanic acid particles, method for producing metatitanic acid particles, and composition for forming photocatalyst

Treated metatitanic acid particles, wherein each treated metatitanic acid particle comprises:

• a particle containing metatitanic acid (TiO(OH)2);
• and
• a metal compound bonded to a surface of the particle via an oxygen atom, the metal compound includes a metal atom and a hydrocarbon group, wherein the metal atom is silicon, aluminum, or titanium,
• wherein the treated metatitanic acid particles:
• (i) have absorption at wavelengths of 450 nm and 750 nm in a visible absorption spectrum,
• (ii) satisfy the following inequality:
• 0.03≤A≤0.3
• wherein A represents a value of {(peak intensity of C—O bond+peak intensity of C═O bond)/(peak intensity of C—C bond+peak intensity of C═C bond} in a C is orbital X-ray Photoelectron Spectroscopy spectrum, and
• (iii) have undergone heat treatment at a temperature in a range of 180° C. or higher and 500° C. or lower.