Tailoring defective conjugated heterocyclic network to make for broaden light absorption and efficient charge separation for photocatalytic application is an urgent assignment for graphitic carbon nitride (g-C3N4) materials. Here we report a ficile "one-pot" solvothermal method to synthesize controllable O-doped g-C3N4 catalysts at low temperature. By this template-free approach, hollow microsphere O doped g-C3N4 products were obtained. Structure characterization reveals that the as-prepared sample has incomplete heptazine heterocyclic ring structure, and appears O doping in the lattice, which may derived from the activated O-2 molecular. With the extending condensation time, the increased heteroelement doping content and narrowed band gap promote the light harvesting and charge separation efficiency. Compared to pristine g-C3N4 prepared under high-temperature calcination, this novel material show remarkably photocatalytic activity for environment pollutant purification and splitting water for H-2 evolution, even though the conduction level decrease. This work highlights that the architecture and electronic properties of g-C3N4 based materials could be facile control through mild solvothermal route, which is a reference way for design and fabricate highly efficient non-metal photocatalyst with peculiar feature. (C) 2017 Elsevier B.V. All rights reserved.