摘要
过氧化氢(H_(2)O_(2))是一种重要的化工产品,广泛应用于污水处理、消毒杀菌和印染漂白等领域.在蒽醌法生产H_(2)O_(2)的过程中,易产生有毒气体并存在爆炸危险.因此,仅利用水、氧气和太阳光即可在合适的光催化剂上生成H_(2)O_(2)的光催化技术备受关注.本课题组报道了通过酸碱自组装法制备的四(4-羧基苯基)卟啉(SA-TCPP)光催化剂,用于生产H_(2)O_(2).该催化剂克服了大部分H_(2)O_(2)光催化剂存在的需要牺牲剂、活性低和光利用率不足等问题,但其性能仍受限于较高的复合率.晶面调控已被证实是改善许多无机催化剂电荷复合的有效策略,然而,对于有机光催化剂,关于暴露晶面与其活性关系的研究仍然较少.本文采用溶解-重结晶法在水和三种有机溶剂的混合物中成功合成了三种具有不同暴露晶面的卟啉光催化剂.即利用卟啉在有机溶剂和水中的溶解度差异,将卟啉先溶解在四氢呋喃(THF)、甲醇(MeOH)或乙二醇(EG)溶液中,随后在水溶液中重新结晶.X射线衍射、高分辨率透射电子显微镜及晶面模拟模型图的结果表明,三种催化剂具有相同的晶体结构,但分别暴露了(400)、(022)和(020)晶面.通过紫外分光光度计测量这些催化剂在氙灯(λ≥420 nm)照射下的光催化活性,结果表明,具有(400)暴露面的卟啉光催化剂的H_(2)O_(2)生产速率最高,可达29.33 mmol L h^(-1)g^(-1),分别是具有(022)暴露面和(020)暴露面的卟啉光催化剂的2.7倍和4.1倍,约是已报道的SA-TCPP光催化剂的1.3倍.通过紫外漫反射、莫特肖特基曲线分析以及LED灯照射下的光催化活性测试,排除了光吸收能力对这三种卟啉光催化剂活性的影响.开尔文探针力显微镜、光生电流密度谱图、晶面模拟模型图和密度泛函理论计算结果表明,活性的差异主要归因于(400)表面暴露的高羧基含量所引发的强内建电场,并且在该暴露面上的内建电场方向有利于空穴从吡咯氮向羧基碳的跃迁,因此阻碍了电荷的快速重组,促进了富有挑战性的水氧化过程,而(020)面由于暴露了最多的吡咯氮和最少的羧基碳,其产生的内建电场强度最弱,且内建电场方向阻碍了空穴向羧基碳的跃迁,因此H_(2)O_(2)生产速率最低.综上所述,本工作通过晶面调控产生强内建电场以加速空穴的迁移,降低了电子空穴复合速率,实现了高H_(2)O_(2)生产速率,为更高效的有机光催化剂的设计和开发提供了新思路.
Three TCPP porphyrin-based nanosheet photocatalysts with exposed(400),(022),and(020)planes were synthesized using a dissolution-recrystallization method in a mixture of water and tetrahydrofuran(THF),methanol(MeOH),and ethylene glycol(EG).The TCPP photocatalyst with the exposed(400)surface exhibited the highest H_(2)O_(2)production rate of 29.33 mmol L‒1 h‒1 g‒1 from only H_(2)O and O2,surpassing the rates observed for ones with exposed(022)and(020)surfaces by factors of 2.7 and 4.1,respectively,and 1.3 times as that of the reported TCPP prepared by a base/acid self-assembling method.This enhancement can be attributed to the strong internal electric field and high carboxyl group content on the(400)surface,which hindered rapid charge recombination and facilitated challenging water oxidation.Hence,successful manipulation of porphyrin exposure to robust IEF planes enhances the photocatalytic activity of the system and provides valuable insights for the design and development of more efficient organic photocatalysts.
作者
邵韵航
张亚宁
陈潮锋
窦帅
娄阳
董玉明
朱永法
潘成思
Yunhang Shao;Yaning Zhang;Chaofeng Chen;Shuai Dou;Yang Lou;Yuming Dong;Yongfa Zhu;Chengsi Pan(Key Laboratory of Synthetic and Biological Colloids,Ministry of Education,School of Chemical and Material Engineering,Jiangnan University,Wuxi 214122,Jiangsu,China;International Joint Research Center for Photoresponsive Molecules and Materials,Jiangnan University,Wuxi 214122,Jiangsu,China;Department of Chemistry,Tsinghua University,Beijing 100084,China)
基金
国家自然科学基金项目(22172065,21908079,21676123,21902009,21707052,U21A20326)
江苏省碳峰值与碳中和科技创新专项基金项目(BK20220023)
国家重点研发计划项目(2021YFB3501900)
江苏省特约教授项目(1046010241211400).
