The photocatalytic reforming of lignocellulose and water (H2O) splitting has emerged as a promising method for generating sustainable hydrogen (H2), offering a solution to the global energy crisis. However, the efficiency of the photocatalytic process is often hampered by the low utilization of sunlight and the recombination of photogenerated charge carriers on the photocatalysts. A sodium-doped graphitic carbon nitride (g-C3N4-Na) was developed through a straightforward co-pyrolysis technique, and the sodium doping not only boosts the light absorption capacity of g-C3N4 but also promotes the separation and migration of photogenerated charge carriers. Subsequently, the H2 evolution rate of g-C3N4-Na6 is 14 times higher than that of pure g-C3N4. Additionally, under visible light irradiation, we have efficiently produced several value-added chemicals (such as mannose, rhamnose, galacturonic acid, glucuronic acid, glucose, and arabinose) from α-cellulose oxidation. This research paves the way for developing new strategies for sustainable and efficient H2 production, contributing to the alleviation of energy crisis and fostering a more sustainable future.