Mott-Schottky photocatalyst composed of Pd nanoparticles and mesoporous carbon nitride functions as an excellent catalyst for dehydrogenation of formic acid to release H2 gas without the formation of CO. The enhanced electron-enrichment of Pd nanoparticles due to charge transfer at the interface of Mott-Schottky contact is the key factor for the exceptional catalytic performance of the material.