Structural design, doping, and construction of heterojunctions are effective strategies for producing highly efficient photocatalytic materials. Herein, N-doped TiO2 was formed on hexagonal C3N4 tube through in-situ hydrolysis of a Ti source on a supramolecular precursor, followed by thermal treatment. As a result, a double-shell microtube, C3N4@TiO2 heterostructure was fabricated. It was worth noting that the supramolecular precursor was prepared from melamine and cyanuric acid, which not only served as a template for the double-shell tubular structure, but also provided nitrogen for the doping of TiO2. The photocatalytic efficiency of C3N4@TiO2 was investigated by conducting hydrogen production experiments. The hydrogen production rate of C3N4@TiO2 was measured to be 10.1 mmol h-1 g-1, which is 4 times and 15 times that of C3N4 and TiO2, respectively. The improved photocatalytic activity of C3N4@TiO2 can be ascribed to (1) the tubular structure that provides a large number of reaction sites and enhances mass transport, (2) the heterojunction that is beneficial to charge separation, and (3) doping of TiO2 with nitrogen which extends its optical absorption range to visible light. This work demonstrates a facile method for synthesizing a highly efficient photocatalyst towards hydrogen evolution by modifying its structure and chemical composition as well as forming a heterojunction.

中文翻译：

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TiO2-C3N4双壳微管：原位制备的异质结构，可增强光催化氢的释放。

结构设计，掺杂和异质结的构造是生产高效光催化材料的有效策略。在此，通过在超分子前体上原位水解Ti源，然后进行热处理，在六角形C3N4管上形成N掺杂的TiO2。结果，制备了双壳微管C3N4 @ TiO2异质结构。值得注意的是，超分子前体是由三聚氰胺和氰尿酸制备的，三聚氰胺和氰尿酸不仅用作双壳管状结构的模板，而且还为二氧化钛的掺杂提供了氮。通过制氢实验研究了C3N4 @ TiO2的光催化效率。经测量，C3N4 @ TiO2的产氢速率为10.1 mmol h-1 g-1，是C3N4和TiO2的4倍和15倍，分别。C3N4 @ TiO2的提高的光催化活性可以归因于（1）提供大量反应部位并增强质量传输的管状结构；（2）有利于电荷分离的异质结；以及（3）掺杂TiO2用氮将其光吸收范围扩展到可见光。这项工作证明了一种通过改变其结构和化学组成以及形成异质结来合成高效的光催化剂以制氢的简便方法。（3）用氮掺杂TiO2，将其光吸收范围扩展到可见光。这项工作展示了一种通过改变其结构和化学组成以及形成异质结来合成高效的光催化剂以制氢的简便方法。（3）用氮掺杂TiO2，将其光吸收范围扩展到可见光。这项工作证明了一种通过改变其结构和化学组成以及形成异质结来合成高效的光催化剂以制氢的简便方法。