Black TiO2: What are exact functions of disorder layer

Among the substantial amount of photocatalyst materials, TiO2 has been enthusiastically studied for a few decades due to its outstanding photocatalytic activity and stability. Recently, black TiO2 consisting of approximately 2nm of thin disorder layer around the surface showed surprisingly high solar hydrogen generation ability. The disorder layer of TiO2 can enhance its light absorption, charge separation, and surface reaction abilities, however exact fundamentals of photocatalytic water-splitting pathways are still ambiguous. Herein, recent progress and investigations on exact functions of disorder layer and its application in photocatalytic CO2 reduction will be discussed. Throughout the comprehensive studies on disorder layer of TiO2, disorder engineering on photocatalyst materials will suggest the further extension of developing solar-fuel production technologies.