Formation of g-C3N4 Nanotubes towards Superior Photocatalysis Performance

Poor charge separation efficiency seriously limits the application of graphitic carbon nitride (g-C3N4) for water splitting. Herein, g-C3N4 nanotubes were created to enhance charge carrier separation for superior H-2 evolution via a thermal polymerizing reaction using melamine crystals prepared through a transitional metal derived re-crystalline process. Melamine crystals were grown with help of transitional metal ions (Fe3+, Co2+, Ni2+, and Mn2+). As prepared crystals have regular shape with an average size of similar to 20 mu m. The growth of (002) facet was limited and another facets corresponding to (011), (210) and (311) promised. The tubular shape is firstly ascribed to the traces amount of transition metal ions in the crystal promise formation of tubular structure. Another key is that regular crystals with low surface energy slow down polycondensation reaction. The tubular g-C3N4 revealed superior photocatalysis performance. Sample Fe3+ R-650 CN prepared using Fe3+ ions modified crystals exhibited enhanced absorbance at 500 nm and decreased band gap. Tubular morphology accelerated electron transfer along the axial direction. The sample revealed the highest photocatalytic hydrogen evolution rate of 7538 mu mol h(-1) g(-1), which is nearly 13.5 times high compared with g-C3N4 nanosheets prepared using similar conditions without transitional metal ions.