A green one-pot approach for mesoporous g-C3N4 nanosheets with in situ sodium doping for enhanced photocatalytic hydrogen evolution

Synchronous nano-structuring and element-doping of g-C3N4 were realized via a green one-pot approach to improve its photocatalytic activity. Na-doped mesoporous g-C3N4 nanosheets of ∼5 nm in thickness were facilely synthesized by calcining a mixture of dicyandiamide and sodium chloride. NaCl not only serves as a confining-reactor to confine the growth of g-C3N4 into mesoporous nanosheets, but also acts as a sodium source for Na-doping. The nanosheets own greater specific surface area, stronger optical absorption and lower recombination of photo-induced electron-hole pairs than bulk g-C3N4, and exhibit an excellent visible-light photocatalytic hydrogen evolution efficiency which is about 13 times that of bulk g-C3N4. Moreover, the thermostable and hydrosoluble NaCl is simply removed and recycled by water and then directly reused in a new synthesis, making the process to be environmental-friendly and sustainable.