Amorphous quantum dots co-catalyst: Defect level induced solar-to-hydrogen production

Photocatalytic water splitting has been regarded as the most economical means for the production of green hydrogen. However, the conversion efficiency of photocatalytic water splitting is still low. Herein, a uniform dispersion of amorphous and nanosized CuOx species is in-situ loaded on the surface of TiO2 to form am-CuOx/TiO2, representing the first-of-its-kind amorphous quantum dots as the co-catalysts for photocatalytic process. Their CuOx particles anchor on the surface of TiO2 via bondings between the surface Ti and Cu as confirmed by X-ray absorption spectroscopy measurements. Notably, ultraviolet photoelectron spectroscopy coupled with density functional theory calculations indicates that the defect energy levels of CuOx act as the collection centers of the electrons photogenerated by TiO2. Therefore, the am-CuOx/TiO2 catalyst exhibits photocatalytic H2 evolution rate of 19.14 μmol/h under LED-365 illumination with the record-breaking AQE value of 52.29 %. This work will enable the design of more efficient photocatalytic green H2 evolution.