Wednesday, 05 February, 2014
Crystalline Carbon Nitride Nanosheets for Improved Visible-Light Hydrogen Evolution
K. Schwinghammer, M. Mesch, V. Duppel, C. Ziegler, J. Senker, and B. Lotsch -
J. Am. Chem. Soc., Vol. 136 (5), pp 1730-1733 (2014)
Nanosheets of a crystalline 2D carbon nitride were obtained by ionothermal synthesis of the layered bulk material poly(triazine imide), PTI, followed by one-step liquid exfoliation in water. Triazine-based nanosheets are 1-2 nm in height and afford chemically and colloidally stable suspensions under both basic and acidic conditions. We use solid-state NMR spectroscopy of isotopically enriched, restacked nanosheets as a tool to indirectly monitor the exfoliation process and carve out the chemical changes occurring upon exfoliation, as well as to determine the nanosheet thickness. PTI nanosheets show significantly enhanced visible-light driven photocatalytic activity toward hydrogen evolution compared to their bulk counterpart, which highlights the crucial role of morphology and surface area on the photocatalytic performance of carbon nitride materials.