A 2D g-C3N4 (pPCN)/rGO heterojunction for photocatalytic hydrogen production is fabricated by a facile dissolution strategy facilitated by H2SO4. The bulk g-C3N4 (CN) can be directly exfoliated into ultrathin protonated g-C3N4 (PCN) nanosheets under the assistance of H2SO4, and PCN can be further modified by rGO in a dissolved state under the electrostatic self-assembly process. The nanocomposite exhibits a large surface area (146.47 m(2)/g) and intimate contact interfaces between pPCN and rGO due to the specific synthesis method. Based on the DRS, PL and photoelectrochemical analyses, the introduction of rGO can greatly improve the light absorption and photogenerated charge carrier separation and transfer of g-C3N4. The optimal pPCN/2 wt% rGO nanocomposite shows an efficient photocatalytic H-2 evolution rate of 715 mu mol g(-1) h(-1) under visible light irradiation, which is 2.6 and 13 times higher than those obtained on pPCN and CN. In addition, a photocatalytic mechanism over a 2D pPCN/rGO heterojunction is proposed. This work offers a new effective strategy for fascinating g-C3N4-based nanocomposites with promising hydrogen generation. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.