Sodium-doped carbon nitride nanotubes for efficient visible light-driven hydrogen production
graphitic carbon nitrides, nanotubes, alkali metal doping, photocatalytic hydrogen production, hydrothermal/thermopolymerization processes, two-step synthesis
ABSTRACT Sodium-doped carbon nitride nanotubes (Nax-CNNTs) were prepared by a green and simple two-step method and applied in photocatalytic water splitting for the first time. Transmission electron microscopy (TEM) element mapping and X-ray photoelectron spectroscopy (XPS) measurements confirm that sodium was successfully introduced in the carbon nitride nanotubes (CNNTs), and the intrinsic structure of graphitic carbon nitride (g-C3N4) was also maintained in the products. Moreover, the porous structure of the CNNTs leads to relatively large specific surface areas. Photocatalytic tests indicate that the porous tubular structure and Na+ doping can synergistically enhance the hydrogen evolution rate under visible light (λ > 420 nm) irradiation in the presence of sacrificial agents, leading to a hydrogen evolution rate as high as 143 μmol·h−1 (20 mg catalyst). Moreover, other alkali metal-doped CNNTs, such as Li x-CNNTs and Kx-CNNTs, were tested; both materials were found to enhance the hydrogen evolution rate, but to a lower extent compared with the Na x-CNNTs. This highlights the general applicability of the present method to prepare alkali metal-doped CNNTs; a preliminary mechanism for the photocatalytic hydrogen evolution reaction in the Nax-CNNTs is also proposed.
Tsinghua University Press
Longshuai Zhang,Ning Ding,Muneaki Hashimoto,Koudai Iwasaki,Noriyasu Chikamori,Kazuya Nakata,Yuzhuan Xu,Jiangjian Shi,Huijue Wu,Yanhong Luo,Dongmei Li,Akira Fujishima,Qingbo Meng, Sodium-doped carbon nitride nanotubes for efficient visible light-driven hydrogen production. NanoRes.2018, 11(4): 2295–2309