【摘要】 石墨相氮化碳（g-C₃N₄）材料是一种极具潜力的有机光催化材料,尤其是在可见光驱动的光催化分解水制氢方面的应用.然而,较差的光生载流子分离效率严重制约了其光催化活性.选择TiO₂作为修饰材料,在g-C₃N₄表面构建合理的异质结构可以有效解决该问题,但需要进行合理的设计.本文通过较为简单的工艺过程,以金属有机框架材料（MOFs）为牺牲模板,制备MOF衍化TiO₂修饰的g-C₃N₄复合光催化剂.制得的MOF衍化TiO₂的比表面积大,约为124.5 m2/g,并由锐钛矿相/金红石相两相混合组成,这会有效增加光催化剂的光生电子分离效率,并提供更多的催化反应活性位点.通过XRD、SEM、TEM、UV-Vis、PL等表征手段,对材料的物相及相关的光谱学、电化学性质进行了详细的表征,并通过成分调控确定了优化工艺参数.通过相关表征结果可以看出,MOF衍化TiO₂修饰的g-C₃N₄复合光催化剂随着TiO₂的负载量提高而表现更好的载流子分离效率,但其可见光响应会随之降低.因此,存在一个最优的负载量可以均衡二者的影响,从而表现出最高的光催化活性.实验发现,TiO₂的质量分数为6%的光催化剂,其光催化制氢活性在可见光（l≥420 nm）驱动下体现了最高的制氢速率,达836μmol/（g·h）.实验结果表明:由MOF衍化TiO₂与g-C₃N₄构建的异质结构可以有效地抑制光生载流子的复合,从而显著提高光催化分解水制氢的性能.更多还原

【Abstract】 Graphitic carbon nitride（g-C₃N₄）is a promising organic photocatalytic material,especially in visible-lightdriven photocatalytic water-splitting hydrogen production. However,poor photogenerated carrier separation efficiency severely restricts the photocatalytic activity of g-C₃N₄. Using titanium dioxide（TiO₂）as modifier and constructing a reasonable heterostructure on the surface of g-C₃N₄ can effectively solve the aforementioned problem,but it needs a reasonable design. In this study,MOF-derived TiO₂-modified g-C₃N₄ composites were prepared through a facile preparation process using metal-organic frameworks（MOFs）as sacrificial template. The prepared MOF-derived TiO₂ has a large specific surface area of 124.5 m²/g and is a mixture of anatase and rutile phases,which can effectively increase the photoelectron separation efficiency of the photocatalyst and provide more active sites for the photocatalytic reaction. XRD,SEM,TEM,UV-Vis,PL,and other characterization methods were used to characterize thephase and related spectroscopic and electrochemical properties of the materials in detail,and the optimized process parameters were determined by composition control. Results show that the MOF-derived TiO₂-modified g-C₃N₄ composite photocatalyst exhibits good carrier separation efficiency with the increase in the loading of TiO₂,but its visible light response decreases accordingly. Therefore,the optimum load to balance the effects of MOF and TiO₂ exists,resulting in the highest photocatalytic activity. Notably,the photocatalytic activity of the photocatalyst with 6% TiO₂ exhibited the highest hydrogen production rate of 836 μmol/（g·h） under visible light（l≥ 420 nm）. The experimental results show that the heterojunction structure constructed using MOF-derived TiO₂-modified g-C₃N₄ can effectively inhibit the recombination of photogenerated carriers,thus significantly improving the photocatalytic decomposition of water for hydrogen production.更多还原