▎ 摘　　要

Surface intact nitrogen-doped graphene oxide quantum dots (iNGO-QDs), which are based on the abundant elements C, H, O, and N, exhibit outstanding photocatalytic performance in H-2 production through water decomposition. In this study, we synthesize the iNGO-QDs by thermally treating graphene oxide sheets in NH3 with subsequent ultrasonic exfoliation. The iNGO-QDs exhibit sizes of 2 to 6 nm and consist of approximately 3 graphitic layers. Nitrogen doping in QD synthesis repairs the vacancy-type defects of GO and introduces n-type conductivity to compensate for the unbalanced charges on p-type GO, thereby suppressing leaks of photogenerated charges. Coexistence of p- and n-domains in the iNGO-QDs may form photochemical diodes to facilitate charge separation. Under visible light illumination, the iNGO-QDs steadily catalyze the production of H2 from an aqueous solution containing triethanolamine. When deposited with Pt as the cocatalyst, the iNGO-QDs exhibit high activity in H2 generation at an apparent quantum yield of 12.8% under monochromatic light (420 nm) irradiation. The high activity of the iNGO-QDs can be attributed to the synergistic effect of the oxygen and nitrogen functionalities in facilitating charge separation and transfer. (C) 2015 Elsevier Ltd. All rights reserved.