Photocatalysts Market Size, Share & Industry Analysis, By Type (Titanium Dioxide (TiO₂), Zinc Oxide (ZnO), Tungsten Oxide (WO₃), Graphitic Carbon Nitride (g-C₃N₄), and Others), By Application (Self-Cleaning Surfaces & Coatings, Air Purification, Water & Wastewater Treatment, Anti-Fogging / Anti-Soiling Coatings, Energy, and Others), and Regional Forecast, 2026-2034