We report the facile and environmental-friendly synthesis of an efficient carbon nitride photocatalyst for hydrogen production and dyes degradation by using a unique supramolecular assembly with an element gradient as the reactant. The element gradient is acquired through the selective removal of barbituric acid from the surface of a supramolecular assembly that comprises barbituric acid, melamine, and cyanucric acid, using hydrochloric acid as a surface modifier. The tailored design of the supramolecular aggregate results in inner and outer parts, which have carbon-rich and carbon-poor domains, respectively. Structural and optical investigations of the new assemblies reveal that the hydrogen–chlorine interaction generates a carbon gradient through the starting supramolecular assembly and to a better packing and structural alignment of the supramolecular units. Detailed X-ray photoelectron spectroscopy and photophysical studies of the final carbon nitride-like materials after calcination at 550 °C indicate that the element gradient across the starting precursor directly projects on the final carbon nitride chemical and element composition, as well as on its optical and photocatalytic properties. The spatial arrangement of the starting monomers leads to the formation of a unique energy-level structure in the final material, which is intended to improve the efficiency of charge separation under illumination and, thereby, result in a strong enhancement of photocatalytic activity toward a high hydrogen production and fast dyes degradation. This work provides new opportunities for the rational design of carbon nitride and other metal-free materials with unique and controllable chemical, optical, and catalytic properties for sustainable energy-related applications.

中文翻译：

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氮化碳光催化剂独特的能带结构和形态设计，用于改进电荷分离和产氢

我们报告了一种高效且高效的氮化碳光催化剂的合成方法，该方法用于生产氢气和染料降解，方法是使用独特的超分子组装体，其中元素梯度作为反应物。通过使用盐酸作为表面改性剂，从包括巴比妥酸，三聚氰胺和氰基酸的超分子组装体的表面上选择性去除巴比妥酸来获得元素梯度。超分子聚集体的定制设计导致内部和外部分别具有富碳域和贫碳域。对新组件的结构和光学研究表明，氢与氯的相互作用会通过起始的超分子组件产生碳梯度，并使超分子单元更好的堆积和结构排列。在550°C下煅烧后，最终的类氮化碳材料的详细X射线光电子能谱和光物理研究表明，跨越原料前体的元素梯度直接投射在最终的氮化碳化学物质和元素组成以及其光学上和光催化性能。起始单体的空间排列导致在最终材料中形成独特的能级结构，这旨在提高光照下电荷分离的效率，从而，导致光催化活性大大增强，从而产生大量氢并快速降解染料。这项工作为合理设计具有独特且可控制的化学，光学和催化特性的氮化碳和其他无金属材料提供了新的机遇，以实现可持续的能源相关应用。