A facile synthetic strategy for nitrogen-deficient graphitic carbon nitride (g-C N ) is established, involving a simple alkali-assisted thermal polymerization of urea, melamine, or thiourea. In situ introduced nitrogen vacancies significantly redshift the absorption edge of g-C N , with the defect concentration depending on the alkali to nitrogen precursor ratio. The g-C N products show superior visible-light photocatalytic performance compared to pristine g-C N .

Defect-rich ultrathin ZnAl-layered double hydroxide nanosheets are successfully prepared. Under UV-vis irradiation, these nanosheets are superior efficient catalysts for the photoreduction of CO2 to CO with water. The formed oxygen vacancies lead to the formation of coordinatively unsaturated Zn(+) centers within the nanosheets, responsible for the very high photocatalytic activities.

Nitrogen-doped porous carbon nanosheets (N-CNS) are synthesized by hydrothermal carbon coating of g-C3 N4 nanosheets followed by high-temperature treatment in N2 . g-C3 N4 serves as a template, nitrogen source, and porogen in the synthesis. This approach yields N-CNS with a high nitrogen content and comparable oxygen reduction reaction catalytic activities to commercial Pt/C catalysts in alkaline media.