Zhang Xinlei, Luo Xiao, Zheng Xusheng, Wu Xiaojun, Xu Hangxun
Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China.
Hefei National Laboratory of Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, Department of Materials Science and Engineering, CAS Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui, 230026, China.
Small. 2019 Oct;15(43):e1903643. doi: 10.1002/smll.201903643. Epub 2019 Sep 3.
Ultrathin 2D conjugated polymer nanosheets are an emerging class of photocatalysts for solar-to-chemical energy conversion. Until now, the majority of ultrathin 2D polymer photocatalysts are produced through exfoliation of layered polymers. Unfortunately, it still remains a great challenge to exfoliate layered polymers into ultrathin nanosheets with high yields. In this work, a liquid-phase protonation-assisted exfoliation is demonstrated to enable remarkably improved exfoliation yields of various 2D N-containing conjugated polymers such as g-C N , C N, and aza-CMP. The exfoliation yields are only 2-15% in pure water whereas they can be substantially improved to 41-56% in 12 m HCl. The exfoliated ultrathin nanosheets possess average thicknesses less than 5 nm and can be easily dispersed in aqueous solutions. More importantly, the exfoliated nanosheets exhibit significantly enhanced photocatalytic activity toward photocatalytic water splitting compared to their bulk counterparts. Further characterizations and computational calculations reveal that protonation of the heterocyclic nitrogen sites in the conjugated polymer frameworks can lead to strong hydrogen bonding between the polymer surfaces and water molecules, resulting in facilitated exfoliation of polymers into the liquid phase. This study unveils an important protocol toward producing ultrathin 2D N-containing conjugated polymer nanosheets for future solar energy conversion.
超薄二维共轭聚合物纳米片是一类新兴的用于太阳能到化学能转换的光催化剂。到目前为止，大多数超薄二维聚合物光催化剂是通过层状聚合物的剥离制备的。不幸的是，将层状聚合物高产率地剥离成超薄纳米片仍然是一个巨大的挑战。在这项工作中，液相质子化辅助剥离被证明能够显著提高各种含氮二维共轭聚合物（如g-C₃N₄、C₃N₄和氮杂共轭微孔聚合物）的剥离产率。在纯水中剥离产率仅为2% - 15%，而在12 m HCl中可大幅提高到41% - 56%。剥离得到的超薄纳米片平均厚度小于5 nm，并且能够很容易地分散在水溶液中。更重要的是，与本体材料相比，剥离后的纳米片对光催化水分解表现出显著增强的光催化活性。进一步的表征和计算表明，共轭聚合物骨架中杂环氮位点的质子化会导致聚合物表面与水分子之间形成强氢键，从而促进聚合物向液相的剥离。这项研究揭示了一种用于制备超薄含氮二维共轭聚合物纳米片以用于未来太阳能转换的重要方法。
