C-Rich Graphitic Carbon Nitride with Cross Pore Channels: A Visible-Light-Driven Photocatalyst for Water Splitting

Carbon nitride is found to be an outstanding metal-free photocatalyst for photocatalytic hydrogen evolution. However, carbon nitride suffers from insufficient light absorption and wide band gap, which limits the photocatalytic efficiency. Herein, we develop a carbon-rich graphitic carbon nitride with cross pore channels. The influence of rich carbon and porous structure on the optical and electrical properties of as-prepared carbon nitride is studied in detail. The carbon-rich carbon nitride exhibits larger surface area, enhanced light-harvesting ability, faster separation rate of photoinduced carriers through abundant carbon rings and narrower band gap than bulk CN. Especially, the carbon-rich carbon nitride displays a much higher hydrogen generation efficiency (551.5 μmol/h), which is approximately 117 times and 2.3 times higher than that of bulk carbon nitride obtained by the calcination of melamine (4.7 μmol/h) and pure CN (240.3 μmol/h), respectively. Moreover, an advanced H2 evolution rate of 3.7 μmol for CN-50 is obtained within 4 h without the addition of Pt cocatalysts, which is two times higher than that of pure CN. More importantly, excellent photostability with a negligible decrease in the catalytic ability for CN-50 can be achieved. This fabrication method can be extended to the design of catalysts with excellent photocatalytic activity for hydrogen generation, CO2 reduction, and many other processes.