Ordered graphitic carbon nitride tubular bundles with efficient electron-hole separation and enhanced photocatalytic performance for hydrogen generation

Abstract

Ordered graphitic carbon nitride (g-C3N4) tubular bundles were successfully prepared by thermal polymerization of complex microcrystals composed of melamine and PEG-PPG-PEG, with the block copolymer serving as a soft sacrificial template. Melamine and PEG-PPG-PEG were found to readily form molecular crystals in hot water via self-assembly processes, which on heating at 550 °C in N2 yielded high specific surface area g-C3N4 tubular bundles. The ordered parallel alignment of the individual g-C3N4 nanotubes (diameter ∼100 nm, length > 5 μm) within the bundles delivered excellent electron transport properties as evidenced by photoelectrochemical and photoluminescence measurements under visible light excitation. The combination of high specific surface area and enhanced electron transport properties imparted the g-C3N4 tubular bundles with outstanding photocatalytic performance. A 1 wt.% Pt/g-C3N4 tubular bundle photocatalyst afforded the remarkable H2 production rate of 16.07 mmol h−1 g−1 in 10 vol.% triethanolamine (TEOA) under visible light (300 W Xe lamp, λ > 420 nm), almost 5 times higher than that of a conventional 1 wt.% Pt/bulk g-C3N4 photocatalyst. Results guide the development of improved g-C3N4 photocatalysts for renewable energy applications.