Generally, the outstanding photoactivity of the semiconductor photocatalyst often attributes to the loaded Pt or H2PtCl6 solution. However, the utilization efficiency of Pt is relatively low due to the agglomeration during the loading or photocatalytic reaction process. Here, we have successfully synthesized the single Pt atoms supported on g-C3N4 nanosheets (Pt-SA-CN) with dilute amounts of Pt (<0.3 wt% Pt) by a facile incipient wetness impregnation. The single Pt atoms are uniformly embedded into the g-C3N4 nanosheets via Pt-N coordination bonds. Surprisingly, with the introduction of single Pt atoms, the Pt-SACN photocatalysts exhibit both higher photocatalytic H-2 evolution and photo-oxidation of NO to NO3. Especially, the PtO2-SA-CN photocatalyst displays the most excellent photo catalytic performance in the series of Pt-SA-CN samples, and even higher than that of the g-C3N4 nanosheets in H2PtCl6 (1 wt% Pt) solution and the Pt loaded on g-C3N4 surface by photodeposition method. The utilization efficiency of Pt has a considerable enhancement and the photoactivity is also improved. The reasons for the enhanced photocatalytic performance of Pt-SA-CN samples are also further discussed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.