Facile synthesis of mesoporous polymeric carbon nitride nanosheets anchored by Pt with ultralow loading for high-efficiency photocatalytic H2 evolution

Facile fabrication of low cost photocatalyst with enhanced activity and high atomic utilization has been in increasing demand for solar energy usage and/or conversion. In this work, a series of mesoporous carbon nitride nanosheets with enlarged specific surface area were synthesized via an inorganic acid-assisted exfoliation method without any soft or hard templates. Ultralow loading of downsized noble metal Pt was anchored on these porous nanosheets and warranted enhanced photocatalytic activity. The formation of mesoporous nanosheets in carbon nitride was expected to boost mass transfer and shorten charge carrier transfer route during photocatalytic reaction. Characterizations revealed that the enlarged conductivity and photocurrent of carbon nitride nanosheets also contributed to the enhanced H2 evolution. The maximum H2 production rates of 172.92 μmol/h and 321 μmol/h could be achieved over these nanosheets derived from melamine and urea under visible light irradiation, which are 10.92 and 2.22 folds as high as that of corresponding bulk carbon nitride, respectively. This exfoliation method was demonstrated to be an efficient and universal method for the preparation of carbon nitride nanosheets with mesoporous structure and high atomic utilization of co-catalyst for H2 evolution from water.