【作者】 胡小红；

【导师】 林道辉； 徐江；

【作者基本信息】 浙江大学 ， 环境科学， 2025， 博士

【摘要】 纳米零价铁（nFe⁰）是降解地下水中有机污染物的常用材料,但不管是水处理还是地下水修复,水会竞争性捕获电子;同时,nFe⁰极易与水反应,导致其钝化失活,显著降低对污染物的还原能力和选择性。如何克服nFe⁰与水的析氢副反应（HER）并提高其降解污染物的选择性,是工程化应用的主要瓶颈,而传统双金属、表面负载等策略难以克服nFe⁰的活性-选择性平衡限制,亟需发展新的改性策略。本论文基于现有研究基础、nFe⁰特性,结合元素亲铁-亲硫性和Lewis酸碱作用,设计了晶格S和Cu或Ni掺杂的改性nFe⁰材料,在保持高空气和水稳定性的同时,实现了高效选择性还原去除三氯乙烯（TCE）、氟苯尼考（FF）及对硝基氯苯（p-NCB）等典型有机污染物,重点阐明了晶格掺杂对nFe⁰晶体结构-理化性质-反应活性-选择性等的调控作用,克服了传统nFe⁰材料的反应活性-选择性-稳定性平衡难题。主要研究结论如下:（1）提出了nFe⁰的亲铁-亲硫元素晶格掺杂策略,阐明了其对nFe⁰还原脱氯性能及机制的调控作用。亲铁元素S的引入可作为桥梁,促进弱亲铁、强亲硫元素Cu在nFe⁰晶格中的均匀掺杂。所制备的晶格共掺杂材料Cu-S-nFe⁰相比nFe⁰,Fe-Fe键增长、Fe⁰晶胞扩张,这使得材料电阻降低、电子传递加快,因而提升了对TCE和FF的脱氯活性（提升20倍）。同时,Cu-S-nFe⁰中Fe的配位数增加,并形成了类似Cu FeS₂结构,使材料具备超疏水性,显著抑制HER反应,对TCE和FF的电子选择性从5–55%增加到80–100%。（2）利用Lewis酸碱作用对nFe⁰进行Ni元素与S元素的晶格掺杂改性,强化了晶格掺杂对nFe⁰选择性还原脱氯的调控作用。与弱亲铁元素Cu不同,强亲铁元素Ni可均匀掺于nFe⁰颗粒中;而且,与S共掺时,Ni以Lewis弱酸与Lewis弱碱S可协同调控nFe⁰材料的结构和性能,即通过调整Ni含量和S前驱体,可实现Fe⁰晶格应变及S形态（FeS和FeS₂）与含量的可控变化。晶格S和Ni掺杂使Fe-Fe键增长、晶胞扩张、S含量和FeS_x增加,故Ni-S-nFe⁰材料的电阻更低且电子传递更快,对水中TCE和FF等目标污染物的脱氯还原活性可达未改性nFe⁰的956倍。掺S形成的FeS和FeS₂结构使材料更疏水,故Ni-S-nFe⁰对水中TCE和FF的电子选择性均可达90%。（3）阐明了晶格掺杂对nFe⁰选择性还原对硝基氯苯的脱硝作用及机制。Ni-S-nFe⁰对对硝基氯苯（p-NCB）的选择性脱硝活性是Cu-S-nFe⁰的3倍,具脱硝优势。这可能与Ni本身具有催化加氢作用相关,由于Ni-S-nFe⁰的疏水性较弱,水分子更易接触活性位点,从而促进*H生成并用于脱硝。此外,Ni-S-nFe⁰对p-NCB的电子选择性和对产物对氯苯胺（p-CAN）的选择性均近100%,降低了p-NCB污染地下水的风险。（4）评估了晶格掺杂nFe⁰的实际应用潜力,阐明了晶格掺杂的潜在优势。超疏水的Cu-S-nFe⁰在水中寿命预计可达2年,优于同类nFe⁰材料,且与Ni-S-nFe⁰一样,在空气中暴露90天后仍保持较高疏水性和约80%的初始Fe⁰含量。Cu-S-nFe⁰和Ni-S-nFe⁰在与TCE或FF分别反应7–30天后,其元素浸出率均不超过0.6%,且在实际水样中,晶格掺杂体系仍能保持对TCE、FF及p-NCB大于90%的还原去除效率和超85%的电子选择性。虽然晶格掺杂略增生产成本（0.2–0.8%）,但由于反应性、选择性和稳定性的提升,材料用量和维护费用可显著减少,说明晶格掺杂nFe⁰具备显著的应用潜力。综上所述,晶格掺杂策略通过调控Fe晶格应变及S形态,提升了材料的疏水性并增强了电子传递性能。此外,该策略同步实现了目标污染物的高活性和高选择性还原;材料优异的稳定性还可降低储存运输成本,有利于工程化应用。研究结果克服了传统nFe⁰在选择性还原典型有机污染物中的局限性,也为开发兼具高活性、高选择性和高稳定性的环境功能材料提供了理论依据与研究思路。更多还原

【Abstract】 Nanoscale zerovalent iron（nFe⁰）is widely used for the degrading organic contaminants in groundwater.However,water,serving as the dominant electron acceptor in both water treatment and in situ groundwater remediation,readily reacts with nFe⁰,leading to passivation and deactivation.This significantly reduces its reduction efficiency and selectivity toward pollutants.Overcoming the hydrogen evolution reaction（HER）and enhancing selective pollutant removal remain key challenges in the practical application of nFe⁰.Traditional strategies,such as bimetallic and surface modifications,fail to break the trade-off among reactivity,selectivity,and stability,highlighting the need for novel approaches.This thesis proposes a lattice doping strategy for nFe⁰ based on siderophile-chalcophile affinities and Lewis acid–base interactions.By incorporating sulfur（S）and either copper（Cu）or nickel（Ni）into the nFe⁰ lattice,the modified materials achieve high stability in air and water while exhibiting efficient and selective reduction of typical contaminants including trichloroethylene（TCE）,florfenicol（FF）,and p-nitrochlorobenzene（p-NCB）.The structure–property–reactivity–selectivity relationships regulated by lattice doping are systematically explored,addressing long-standing limitations of conventional nFe⁰.The main conclusions are as follows:（1）A siderophile-chalcophile co-doping strategy has been developed,enabling uniform incorporation of Cu into the Felattice using S as a bridging element.The resulting Cu-S-nFe⁰demonstrated Fe–Febond elongation and unit cell expansion,which reduced resistance and enhanced electron transfer,increasing dechlorination activity toward TCE and FF by 20-fold.Furthermore,the formation of a Cu FeS₂-like structure imparted superhydrophobicity,suppressed HER by approximately 150-fold,and improved electron selectivity from 5–55%to 80–100%.（2）Co-doping with Ni and S via Lewis acid–base interaction further enhanced performance.Unlike weakly siderophilic Cu,strongly siderophilic Ni was uniformly incorporated into the nFe⁰ particles.Co-doping with S allowed tunable Felattice strain and S species（FeS and FeS₂）by adjusting precursor ratios.The resulting Ni-S-nFe⁰ showed improved hydrophobicity,lower resistance,and up to 956-fold enhancement in TCE and FF dechlorination activity,with electron selectivity reaching 90%.（3）The selective denitration of p-NCB using lattice-doped nFe⁰ was investigated.Ni-S-nFe⁰ demonstrated approximately 3-fold higher selective denitration reactivity toward p-NCB compared to Cu-S-nFe⁰,owing to Ni’s intrinsic catalytic hydrogenation activity and relatively weaker hydrophobicity that facilitates*H species generation.Moreover,Ni-S-nFe⁰ achieved nearly 100%electron selectivity and product selectivity toward p-chloroaniline（p-CAN）,thus minimizing the environmental risks associated with p-NCB in groundwater.（4）The practical potential of lattice-doped nFe⁰ was assessed.Cu-S-nFe⁰ exhibited a projected aqueous lifetime of up to 2 years.Both Ni-S-nFe⁰ and Cu-S-nFe⁰ retained strong hydrophobicity and nearly 80%of their initial Fe⁰ content after 90 days of air exposure,with metal leaching below 0.6%after 7–30 days of reaction with TCE or FF.In real water,both lattice-doped materials achieved>90%removal and>85%electron selectivity for TCE,FF,and p-NCB.Despite a slightly increased material cost（0.2–0.8%）,enhanced performance reduced material usage and maintenance,supporting strong application potential.In summary,lattice doping with S and Cu or Ni precisely regulated Felattice strain and S species,improving hydrophobicity and electron transfer while enabling highly active and selective reduction of target contaminants in water.The outstanding air and water stability further reduces storage and transport challenges during engineering applications.This study breaks through the conventional limitations of nFe⁰ in the selective reduction of organic pollutants and provides new theoretical foundations and insights for the future development of advanced environmental functional materials with high reactivity,selectivity,and stability.更多还原