A divalent copper salt and/or trivalent iron salt is supported on a surface of a metal ion-doped titanium oxide obtained by doping titanium oxide with metal ions to give a metal ion-doped titanium oxide with a valence band potential of 3 V or more (vs. SHE, pH = 0) and a bandgap of 3 V or less between the valence band and an energy level of electrons excited from the valence band (including conduction band minimum potential and isolated potential). The metal ion-doped titanium oxide can be made to exhibit strong oxidative decomposition activity when irradiated with visible light based on the fact the divalent copper salt or trivalent iron salt functions as a catalyst for multi-electron reduction of oxygen.對氧化鈦摻雜金屬離子,並在將價電子帶的電位設為3V(vs. SHE,pH=0)以上且將價電子帶與由價電子帶所激發後的電子的位準(包含傳導帶下端電位、孤立電位)之能帶隙(band gap)設為3V以下而成之金屬離子摻雜氧化鈦的表面,保持銅二價鹽及/或鐵三價鹽。銅二價鹽或鐵三價鹽的作用,係利用作為氧的多電子還原觸媒,在可見光照射下,能夠使金屬離子摻雜氧化鈦顯現高氧化分解活性。
