联吡啶基共价三嗪框架负载单位点钴用于光催化分解水产氧  

Anchoring single Co sites on bipyridine-based covalent triazine framework for efficient photocatalytic oxygen evolution

作　　者：孙瑞雪 胡勋亮 舒畅 郑黎荣[2] 汪圣尧 王笑颜 谭必恩[1] Ruixue Sun;Xunliang Hu;Chang Shu;Lirong Zheng;Shengyao Wang;Xiaoyan Wang;Bien Tan(Key Laboratory of Material Chemistry for Energy Conversion and Storage,Ministry of Education,Hubei Key Laboratory of Material Chemistry and Service Failure,School of Chemistry and Chemical Engineering,Huazhong University of Science and Technology,Wuhan 430074,Hubei,China;Beijing Synchrotron Radiation Facility,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;College of Science,Huazhong Agricultural University,Wuhan 430070,Hubei,China)

机构地区：[1]华中科技大学化学与化工学院,材料化学与服役失效湖北省重点实验室,能量转换与存储材料化学教育部重点实验室,湖北武汉430074 [2]中国科学院高能物理研究所,北京同步辐射装置,北京100049 [3]华中农业大学理学院,湖北武汉430070

出　　处：《Chinese Journal of Catalysis》2023年第12期159-170,共12页催化学报（英文）

基　　金：国家自然科学基金(22161142005,21975086);国际科技创新合作重点专项(2018YFE0117300);湖北省科技厅(2019CFA008).

摘　　要：氢能是重要的清洁能源,如何低成本获取氢能是其走向实际应用的重要挑战.利用太阳能驱动半导体光催化剂分解水制氢是解决这一挑战的理想途径之一.光催化全解水包括两个半反应,即析氢反应(HER)和析氧反应(OER).其中,光催化OER半反应涉及四个电子的转移(包括O–H键断裂和O–O键形成),其动力学速率远低于两电子转移的HER半反应,因此被认为是光催化全解水的决速步骤.欲实现高效光催化全解水,首先需解决光催化OER半反应动力学缓慢的问题,因此开发高效的OER光催化剂成为当务之急.受单原子催化剂的启发,本文设计并合成了联吡啶基共价三嗪框架(CTF-Bpy),因CTF-Bpy骨架上存在周期性的联吡啶官能团作为金属配位位点,并且有很好的结晶性以及合适的能带结构,是良好的光催化OER反应载体材料.然后通过简单的浸渍配位处理,将单位点的钴作为助催化剂引入到CTF-Bpy中,并用于光催化OER.X射线光电子能谱和X射线近边吸收光谱结果表明,钴是以单位点的Co^(2+)形式存在的.在可见光(λ≥420 nm)照射下,CTF-Bpy-Co在初始1 h内的平均析氧速率为3359μmolg^(–1)h^(–1),5 h内的平均析氧速率为1503μmolg^(–1)h^(–1),光催化性能超过大多数多孔有机聚合物基光催化剂.在420 nm单波长氙灯照射下,CTF-Bpy-Co的光催化析氧表观量子产率(AQY)为0.466%.此外,CTF-Bpy-Co可实现连续析氧40 h,总析氧量可达到180μmol.为明确单位点钴在光催化OER中所起的重要作用,采用相同钴含量的不同形式钴基粒子(游离的Co^(2+),Co,CoO,Co_(2)O_(3)和Co(OH)_(2))作为助催化剂引入CTF-Bpy骨架中进行对比.结果发现,配位的CTF-Bpy-Co表现出最好的光催化析氧效果,表明单位点钴在光催化OER中具有较大的优势.采用密度泛函理论研究了CTF-Bpy-Co的差分电荷密度,并结合上述实验结果提出了CTF-Bpy-Co光催化OER的机理:在可见光激发下,CTF-Bpy-Co光催�The photocatalytic oxygen evolution reaction(OER)is a half-reaction of water splitting for oxygen evolution,faces the drawback of sluggish kinetics.Developing highly efficient photocatalysts for OER represents a significant challenge in the field of water splitting advancement.Herein we report the bipyridine-based covalent triazine framework(CTF-Bpy)with the periodic metal coordination sites and suitable band gap position for efficient photocatalytic oxygen evolution.Single Co sites are introduced into CTF-Bpy as cocatalyst through a facile immersion treatment.The obtained CTF-Bpy-Co exhibited remarkable photocatalytic oxygen evolution performance,achieving an initial rate of up to 3359μmol g~(–1)h~(–1)within the first hour and an average rate of 1503μmol g~(–1)h~(–1)over 5 h under visible light irradiation(λ≥420 nm),which exceeds most of the reported porous organic polymers.Moreover,CTF-Bpy-Co can achieve continuous oxygen evolution for a duration of 40 h and the total oxygen production amount of up to 180μmol.Charge density difference using density functional theory calculations confirm that the Co single site is the reaction site that drives the photooxidation of water to generate oxygen.

关 键 词：共价三嗪框架 联吡啶 单位点钴 光催化产氧 

分 类 号：O64[理学—物理化学]