Graphitic carbon nitride (g-C3N4) has aroused intense expectations owing to its outstanding visible-light-response capability for hydrogen generation from water. However, the low-yield, low practical surface area and high photogenerated charge recombination rate severely limits its photocatalytic performance.Here, in this study high-yield synthesis of g-C3N4with a large surface area has been achieved successfully through an in situ pyrolysis of cyanamide with the assist of the bifunctional urea. During the synthesis process, urea may decompose into a lot of ammonia and carbon dioxide, which acts as the supplementary-nitrogen-source and bubble-generating template respectively. It is found that the surface area and photocatalytic activity can be controlled by adjusting the addition of the environmentally friendly bifunctional urea. The as-prepared g-C3N4exhibits unique optical activity as well as photoelectriochemical activity for solar-to-chemical conversion, and this simple bifunctional method may open a new pathway for designing and optimizing of photocatalysts.