▎ 摘　　要

NOVELTY - Photocatalyst comprises a nanocomposite comprising oxides of tantalum and niobium or non-metal-doped oxides of tantalum and niobium or both. USE - Photocatalyst for liquid purification. ADVANTAGE - The photocatalyst efficiently degrades pollutants or contaminants present in liquid under visible, ultraviolet or solar radiation. DETAILED DESCRIPTION - INDEPENDENT CLAIMs are included for: 1. a A liquid purification device, which comprises a float and a photocatalyst nanocomposite sheet or thin film mounted on or inserted in said float, where the float is configured to float upon a fluid, where the photocatalyst nanocomposite sheet or thin film comprises a photocatalyst and is configured to decompose at least a portion of pollutant(s) present in the liquid; and 2. a method for liquid purification, which involves contacting the liquid with a photocatalyst or the device in presence of visible light, ultraviolet light or solar radiation.