Low temperature fuel cells, with the features of clean, environmental friendliness, and high energy density, are considered as ideal future green energy sources. It has been recently demonstrated that the activities and stabilities of traditional fuel cell reactions can be improved by using photo-functional electrodes with assistance of light illumination. Two-dimensional (2D) heterostructure of g-C3N4/MoS2 was demonstrated to be a promising photocatalyst. Herein, we used g-C3N4/MoS2 nanosheets as a photo-functional substrate for the decoration of Pt nanoparticles and then applied on fuel cell electrocatalytic reactions. Comparing with traditional electrocatalytic reactions, the electrocatalytic performances of the as-synthesized Pt/g-C3N4/MoS2 for the oxidation of methanol, ethanol, and formic acid upon visible light illumination are improved with 6.5, 2.2, and 2.5 times, respectively. The decisive factors in the improved catalytic performances are the synergistic effect of photo&electro-process and the effective charge separation in the designed 2D/2D g-C3N4/MoS2 heterostructure.