二维C3N4基S型异质结产氢光催化剂的构建与性能增强机理

Employing photocatalytic technology in water splitting for hydrogen production is an effective strategy to relieve energy shortage. Graphitic carbon nitride (g-C3N4) is an easy-to-prepare 2D photocatalytic material with visible light response. However, its independent photocatalytic H2 production activity is poor, which is mainly due to the high recombination rate of photogenerated electrons and holes. This project intends to prepare g-C3N4-based S-scheme (Step-scheme) heterojunction photocatalyst, in which an oxidation photocatalyst is exploited to consume the useless photogenerated holes in g-C3N4 by providing photogenerated electrons with weak reduction ability. As a result, the recombination of photogenerated electrons and holes in g-C3N4 is inhibited, and eventually enhanced H2 production activity is expected. The effect of preparation method, chemical composition and nonmetal impurity on the structural property and H2 production activity of the composites will be investigated. In-situ XPS and first-principle calculation will be performed to reveal the interfacial interaction between different constituents, including the electron transfer upon contact of different phases, band bending and formation of built-in electric filed, as well as the migration of photogenerated charge carriers and reduction process of H2 production under light irradiation. This project is expected to elucidate the activity enhancement mechanism of g-C3N4-based S-scheme heterojunction photocatalyst, thus providing experimental and theoretical basis for the construction of g-C3N4-based photocatalytic systems with excellent H2 production performance.

将光催化技术应用于分解水制氢是缓解能源短缺问题的有效途径之一。石墨相氮化碳（g-C3N4）是一种具有可见光响应、制备方法简单的二维光催化材料。然而，单一g-C3N4光催化剂的产氢活性较低，主要是因为光生电子和空穴的复合率高。本项目拟制备g-C3N4基S型（Step型）异质结光催化剂，通过氧化型光催化剂中还原能力弱的光生电子消耗掉g-C3N4的光生空穴，抑制g-C3N4中光生电子与空穴的复合，最终提高产氢活性。研究复合物的制备方法、化学组成、g-C3N4中非金属杂质元素的引入对复合物的结构和产氢活性的影响。借助原位XPS和第一性原理计算，揭示复合物中界面的相互作用，包括两相接触后的电子转移、能带弯曲、内建电场的形成，以及光照下光生载流子的迁移和制氢的还原反应过程。阐明g-C3N4基S型异质结光催化剂的性能增强机理，为构建具有优异产氢活性的g-C3N4基光催化体系提供实验和理论基础。

光催化分解水制氢是解决能源短缺问题的有效途径之一。石墨相氮化碳（g-C3N4）是一种具有可见光响应、制备方法简单、化学稳定性强的二维光催化材料。然而，受限于光生电子和空穴的快速复合，单一g-C3N4光催化剂的产氢活性很低。本项目研究了g-C3N4基S型（Step型）异质结光催化剂的制备方法、产氢活性和光催化机理，考查了杂质元素对g-C3N4基S型异质结界面电子相互作用和表面反应过程的影响。结果表明g-C3N4基S型异质结光催化剂具有高的载流子分离效率和优异的产氢性能，非金属原子（如O和S）和金属原子（如Pt）的引入能够提高内建电场强度、促进光生电子和空穴的迁移、增强反应物分子的吸附、优化还原反应过程。研究结果发表在Carbon Energy、Chinese Journal of Catalysis、Journal of Materiomics、Small Struct.、Acta Phys. -Chim. Sin.和Frontiers in Nanotechnology等国内外刊物上。发表论文19篇，其中高被引论文3篇，热点论文2篇。这些论文的总被引次数超过800次。项目执行期间，项目负责人连续3年入选科睿唯安全球高被引研究人员，参加国内外学术会议5次，其中作报告1次。