直接Z型g-C3N4纳米复合材料体系的设计、构建及光催化性能研究

Recently, graphite-like carbon nitride (g-C3N4) received extensive attention as a new, green and environmental protection and energy materials with promising applications. The absorption spectra of g-C3N4 is narrow with high recombination rate of photogenerated electron-hole pairs. In order to solve this problem, researchers explored more efficient photocatalysts by ion doping, noble metal loading and synthetizing semiconductor composites, but these methods all have drawbacks. Based on Z-Scheme mechanism, this project is structural designed by controlling the low conduction band and high valance band of the semiconductors to construct a Z-Scheme structure, which can enhance the separation rate of photogenerated electron-hole pairs and improve the redox ability of the composite photocatalyst, creating a new method for photodegradation and water-splitting. The in-situ crystallization and mixed calcination are conducted to synthesize the Z-Scheme structured g-C3N4 based composites, in order to improve the ability of photocatalytic degradation of organic dye, phenols, gaseous pollutant (NO) and hydrogen evolution, combining with structural characterization and theoretical calculations to investigate the mechanism, which is expected to better address the current problems of g-C3N4 photocatalyst.

类石墨烯型氮化碳(g-C3N4)作为一种绿色环保、有广泛应用前景的环境能源新材料受到广泛关注。为了解决g-C3N4的光吸收范围较窄、光生电子-空穴对复合几率高等问题，人们通过离子掺杂、贵金属沉积和半导体复合等方法改性以提高其光催化活性，但这些方法都有其不足。本项目基于Z机理进行结构设计和调控，使低导带半导体与高价带半导体复合成Z结构以驱使光生电子-空穴有效分离，同时提高复合光催化剂的还原氧化能力，在光催化降解和光解水制氢方面探讨新途径。拟采用原位结晶、混合煅烧等方法合成Z机理的g-C3N4纳米复合光催化材料，提高其光催化降解液体污染物有色染料及酚类、气体污染物NO和光氧化还原水产氢的能力，结合结构表征和理论计算探讨其机理，可望更好地解决g-C3N4光催化剂目前存在的问题。

类石墨烯型氮化碳(g-C3N4)作为一种绿色环保、有广泛应用前景的环境能源新材料受到广泛关注。为了解决g-C3N4的光吸收范围较窄、光生电子-空穴对复合几率高等问题，本项目依据构建异质结可提升光催化性能，制备了g-C3N4/Bi4O5I2、Bi2O2CO3/g-C3N4等g-C3N4基异质结光催化剂，同时通过形貌调控构建了多孔层状、牛角状、卤素离子掺杂型g-C3N4，通过对所制g-C3N4基复合光催化体系进行有机污染物降解、光解水产氢，以及二氧化碳还原等性能的测试，提出所制复合光催化体系相较于原体相g-C3N4其光催化活性得到了较大的提升，且光催化性能稳定，通过相关光电化学性能的表征以及相应的电子能带结构、态密度等理论计算阐释了所制复合半导体材料和新颖形貌中的光生载流子的分离机理，为研制高催化量子效率光催化剂提供了大量的参考。此外，通过在g-C3N4表面接枝羟基，实现了光催化水分解产氢活性的大幅提高。实验和理论计算发现表面羟基接枝在g-C3N4的碳原子上，其局域极化作用增强了局部载流子分离效率，提高了体相电荷分离效率、界面电荷传递效率和载流子密度。该工作有望为催化剂表面极化设计增强光催化活性提供更多的参考。最后，将g-C3N4和钼系超级电容器材料MoO3复合，根据g-C3N4和MoO3的能带结构以及rGO的费米能级，得出它们具有匹配的能带结构，有利于形成Mott-Schottky异质结结构促进光催化活性。在项目在研期间，共发表相关的国际SCI论文10篇，为研制高催化量子效率光催化剂提供了参考。