PROBLEM TO BE SOLVED: To provide a photocatalyst composition and an element exhibiting a desired photocatalytic activity level and transparency.SOLUTION: A photocatalyst composition is a transparent photocatalyst composition including at least one photocatalytic material and at least one cocatalyst. The cocatalyst is capable of improving the catalytic performance of the photocatalyst at least approximately twice with regard to a measurement of the photocatalytic decomposition rate of acetaldehyde. The photocatalyst and the cocatalyst have refractive indices within approximately 0.75 of each other. The photocatalyst includes WO3, TiO2, or Ti(O, C, N)2:Sn.SELECTED DRAWING: Figure 8【課題】所望の光触媒活性レベルおよび透明性を呈示する光触媒組成物および要素の提供。【解決手段】少なくとも１つの光触媒材料と少なくとも１つの助触媒とを含む透明光触媒組成物であって、助触媒が前記光触媒の触媒性能を、アセトアルデヒドの光触媒的分解率の測定において少なくとも約２倍向上させることができ、光触媒および前記助触媒が互いの約０．７５以内である屈折率を有し、光触媒が、ＷＯ３、ＴｉＯ２、またはＴｉ（Ｏ，Ｃ，Ｎ）２：Ｓｎを含む光触媒組成物。【選択図】図８
