A dye-sensitive photocatalytic H-2 evolution reaction (HER) system with photogenerated carrier directed conduction was constructed. The protonated g-C3N4 combines with the sheet-like Co MOF to form a 2D/2D heterojunction via electrostatic self-assembly. The protonated g-C3N4 and 2D Co-MOF directionally adsorb Eosin Y (EY) and triethanolamine (TEOA) molecules through hydrogen bond and complexation to achieve a whole photocatalytic system. The integral structure effectively facilitates the utilization of dye sensitizer and hole sacrificial agent to achieve the effective and stable photocatalytic H-2 evolution capacity. The photocatalytic hydrogen evolution rate of g-C3N4 after protonation is 1.88 times as high as that of the original g-C3N4. On the basis of 2D/2D heterojunction, Co MOF is doped with rare earth element Sm. The 4f electrons and the difference valences (Sm3+ and Co2+) further suppress the reorganization of photogenerated excitons to achieve highly efficient photocatalytic HER. The directional coupling of sensitizer and electron sacrificial agent combined with rare earth element doping makes the photocatalytic HER rate of the composite material reached 73.42 mu mol.h(-1) within 5 h under simulated sunlight. (c) 2020 Elsevier Inc. All rights reserved.