MXene/MnO_(2)对有机微污染物的类芬顿氧化降解效能与机理  

Nano-MnO_(2)anchored on exfoliated MXene with exceptional and stable Fenton oxidation performance for organic micropollutants

作　　者：文涛 郭思胜 赵恒新 郑宇琦 张馨月 顾鹏程 张塞 艾玥洁 王祥科[1] Tao Wen;Sisheng Guo;Hengxin Zhao;Yuqi Zheng;Xinyue Zhang;Pengcheng Gu;Sai Zhang;Yuejie Ai;Xiangke Wang(MOE Key Laboratory of Resources and Environmental Systems Optimization,College of Environmental Science and Engineering,North China Electric Power University,Beijing 102206,China;School of Resources and Environment,Anhui Agricultural University,Hefei 230036,Anhui,China;Faculty of Environment and Life,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]华北电力大学环境科学与工程学院,资源与环境系统优化教育部重点实验室,北京102206 [2]安徽农业大学资源与环境学院,安徽合肥230036 [3]北京工业大学环境与生命学院,北京100124

出　　处：《Chinese Journal of Catalysis》2024年第6期215-225,共11页催化学报（英文）

基　　金：国家重点研发计划(2018YFC1900105);国家自然科学基金(22006002,22106046);科学挑战计划(TZ2016004);北京市杰出青年科学家计划.

摘　　要：芬顿高级氧化技术是降解有机微污染物的有效手段.过一硫酸盐(PMS)类芬顿技术因具有高效的氧化剂利用率和较宽的pH操作范围,已成为目前工业中过氧化氢芬顿技术的一种有前途的替代品.非均相催化剂能够有效活化PMS,产生多种活性自由基,从而氧化降解有机微污染物.二维过渡金属碳化物/氮化物(MXene)具有较好的电子传输效率和可调的表面官能团,是一种良好的非均相催化材料.然而,MXene的不稳定性、反应体系的自聚集作用和不明确的活性氧(ROS)生成机制极大地限制了它们在实际环境中的广泛应用.鉴于剥离的MXene中钛的高反应活性缺陷可以原位锚定过渡金属材料,本文通过氧化还原策略,将MnO_(2)纳米颗粒原位沉积在MXene纳米片上制备了MXene/MnO_(2)复合材料.X射线衍射图中(002)峰的偏移、透射电镜和电子衍射环图中交错的晶格条纹等表征结果表明,MnO_(2)纳米颗粒均匀地负载在剥离的MXene纳米片上.X射线光电子能谱证实了MXene表面钛缺陷与MnO_(2)纳米颗粒通过氧化还原作用相连接.同时,通过调整反应时间确定了18 h原位沉积制备的MXene/MnO_(2)具有最佳的产率和双酚A降解速率.此时的复合材料能够在4 min内活化PMS去除95.9%的BPA(50 mg/L),矿化效率达到了51.2%,表现出较好的催化性能.电子顺磁共振和淬灭实验结果表明,MXene/MnO_(2)活化PMS降解BPA为非自由基途径.实验观察结合密度泛函理论计算表明,大量暴露的锰位点有效吸附并活化PMS,从而促进了单线态氧的产生.通过高价Mn-oxo相直接生成1O_(2)的普遍途径具有较高的能垒(3.34 eV).相比之下,•OOH作为中间体产生1O_(2)的途径(1.84 eV)在能量上更可行.得益于MXene的快速电荷转移能力和MnO_(2)强PMS活化能力的双重优势,工程化的MXene/MnO_(2)/PVDF催化膜对京密引水渠河水中的有机微污染物表现出高效的活性和出色的长期稳定性.综上,本文通Peroxymonosulfate(PMS)Fenton-like systems have emerged as promising alternatives to hydrogen peroxide(H2O_(2)).Fenton systems are currently used in the industry owing to their highly efficient utilization rate of oxidizing agents and wide operating pH ranges.Heterogeneous Fenton-like catalysts are promising candidates in this regard.However,self-aggregation and generation of ambiguous reactive oxygen species greatly restrict their broad application in practical settings.Herein,a redox reaction between exfoliated MXene and KMnO4 facilitates the in-situ deposition of MnO_(2)nanoparticles on the surface of Ti-deficient vacancies of MXene(MXene/MnO_(2)).Owing to the advantages of MXene with fast charge transfer and MnO_(2)with strong PMS activation ability,the engineered MXene/MnO_(2)@PVDF catalytic membrane exhibited enhanced activity and excellent long-term stability for various refractory organic pollutants.Experimental observations,combined with density functional theory calculations,revealed that the exposed Mn sites effectively promoted the generation of 1O_(2).Interestingly,the widespread pathway for the direct generation of 1O_(2)via high-valent Mn-oxo phases has a high energy barrier(3.34 eV).In contrast,the pathway that uses the•OOH species as intermediates to produce 1O_(2)is energetically more viable(1.84 eV).This work offers insights into the in-situ engineering of transition metal-oxides on MXene-based membranes,facilitating their implementation in remediating micropollutant-contaminated environmental water.

关 键 词：MXene 二氧化锰 过一硫酸盐 单线态氧 类芬顿反应 

分 类 号：X703[环境科学与工程—环境工程] O643.36[理学—物理化学]