Abstract Photocatalytic efficiency of graphitic carbon nitride (g–C3N4) has been hindered by fast carrier recombination and high reaction energy barriers, which can be improved by combining a semiconductor with a large work function. Based on this strategy, we synthesized a novel Pt/t–ZrO2/g–C3N4 composite by integrating g–C3N4 with tetragonal ZrO2 and Pt nanoparticles. Results of experimental measurements and density functional theory simulation demonstrate that the carrier lifetime, transferability and energy barriers of catalysts depend on their work function. The optimal composite exhibits an extraordinary catalytic ability for hydrogen generation of 722.5 μmol(gh)−1 and solar–to–hydrogen energy conversion efficiency of 0.215% under visible–light irradiation, and high catalytic stability. The modification strategy could be applied to designing various different high–efficient catalysts by selecting semiconductors with suitable work functions.