The development of efficient catalysts for hydrogen evolution reaction (HER) presents a huge technical challenge. Graphitic carbon nitride (g-C3N4) is a promising metal-free, low cost, environment-friendly photocatalyst for HER that is driven by visible light. In this work, the authors provide new insight into the photocatalytic natures of g-C3N4 materials and their dependences on grain size, porosity, chemical structure, and photophysical properties. Three different precursors (urea, melamine, and dicyandiamide) and two gas atmospheres (air or N2) are used to produce various g-C3N4 materials. The use of urea and air leads to the formation of small grain C3N4 networks and porous structures with large surface areas. HER catalytic activity is promoted by large surface areas and the presence of terminal amine groups, and generation of small-sized Pt nanoparticle co-catalysts with narrow size distribution on the surface of g-C3N4. For samples with similar surface areas, band gaps and lifetimes of photogenerated charge carriers critically determine photocatalytic activities. By examining combinations of the above-mentioned factors, urea driven g-C3N4 produced in a N2 atmosphere is found to exhibit the best photocatalytic activity (up to 130 μmol h−1 g−1).
Bibliographical noteFunding Information:
This work was supported by Inha University and grants from the Center for Advanced Soft Electronics as a Global Frontier Project (CASE-2013M3A6A5073173) and Basic Science Research Program (NRF-2015R1C1A1A02036958) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning. S.P. thanks the Busan Center at the Korea Basic Science Institute (KBSI) for the XPS analysis.
All Science Journal Classification (ASJC) codes
- Environmental Science(all)
- Process Chemistry and Technology