【作者】 江民华；

【导师】 陈水亮；

【作者基本信息】 江西师范大学 ， 化学， 2021， 博士

【摘要】 微生物电化学技术（MET）具有产能和污水处理的双重功能,可以在一定程度上解决能源和环境问题。金属材料,如不锈钢具有优异的导电和加工性能,可作为微生物电化学系统（MES）的阳极材料和集流体。然而,金属材料由于生物相容性较差以及可能被腐蚀的风险,通常不能直接用来作为阳极材料。表面修饰是一种提升金属材料生物相容性和耐腐蚀性能的常用方法。本文提出了一种反应性粘结纳米碳修饰策略来修饰金属材料,以制备MES的电极材料。一方面将该策略用于制备金属基生物阳极,以提升金属材料的生物相容性和耐腐蚀性能,从而提升其微生物电催化性能;同时,在修饰层中引入电子中介体强化了电子传递,进一步提升了金属基生物阳极的微生物电催化性能;另一方面,利用该策略将碳基氧气还原催化剂固定到金属集流体,制备金属基氧气还原反应阴极;最后,利用反应性粘结纳米碳制备的金属基材料作为导电生物膜载体,用于传统的生物膜法污水处理系统,以强化微生物电化学反硝化。主要包括以下内容:（1）反应性粘结纳米碳制备高性能金属基生物阳极。以反应性粘结剂（如酚醛树脂,PFR）和纳米碳导电材料（如炭黑,CB）按一定比例制备导电分散液（CB/PFR）,用于金属表面修饰。粘结强度测试表明,使用PFR粘结的不锈钢的拉伸强度是聚合物粘结剂Nafion粘结不锈钢强度的5倍。其优异的粘结强度归因于PFR低聚物在热交联过程中与金属（Me）发生了反应,形成了C-O-Me化学键。根据超声冲击测试和微生物电催化性能的结果,对CB与PFR的比例进行优化。结果表明,当CB的质量分数为0.4时（CB/PFR-0.4）,金属生物阳极的修饰涂层同时具备足够的粘结强度和优异的微生物电催化性能,如修饰的不锈钢电极能够产生1.48 m A cm^-2的面积电流密度,是传统的石墨板阳极的1.6倍。反应性粘结表面修饰策略同时还提升了金属基生物阳极的耐腐蚀性能。此外,该修饰策略可应用于常见的金属材料（如铁、铜、镍和钛等）和不同的金属结构（如网、通道孔结构、泡沫和刷等）,且都表现出优异的微生物电催化性能;其中,具有通道孔结构的不锈钢蜂窝电极能够产生约15 m A cm^-2的面积电流密度,泡沫镍电极能够产生78 m A cm^-3的体积电流密度。该性能是目前文献报道的金属基生物阳极的最佳性能。该反应性粘结修饰策略不局限于某一种反应性粘结剂和导电填料,通过替换反应性粘结剂（如密胺树脂,MFR）和导电填料（如碳纳米管,CNTs）,所修饰的金属基生物阳极同样表现出优异的微生物电催化性能,说明该修饰策略具有广泛的普适性。（2）金属基生物阳极原位引入中介体强化电子传递研究。在第（1）部分金属表面修饰的基础上,为了强化微生物与生物阳极表面的电子传递,本章通过空气中热氧化和硝酸氧化的方式对导电碳材料CB进行氧化改性,以引入含氧官能团。电化学测试表明,500℃热氧化的炭黑（CB-500）和硝酸溶液氧化的炭黑（CB-N）有明显的醌式/酚式结构相互转换的氧化还原电对,说明其表面引入了一定的醌式基团,可以作为间接电子传递中介体。此外,电导率结果表明,CB-500因为在高温热氧化过程中去除了部分无定型碳,其石墨化程度得到了提升,因此其电导率也得到了较大提升;而CB-N因为引入了过多的含氧基团,其电导率明显下降。微生物电催化性能表明,CB-500修饰的不锈钢基生物阳极性能最好,比原始CB修饰的不锈钢生物阳极性能提升了20%。这主要归功于电导率的提升强化了直接电子传递和表面醌式结构的引入强化了间接电子传递的协同作用。本章研究表明,通过简单热氧化的方法,提高了CB的电导率,并在其表面原位引入醌式/酚式基团,强化了直接电子传递和间接电子传递,提升了金属基生物阳极性能。（3）反应性粘结碳基催化剂制备金属基氧气还原阴极研究。基于第（1）部分得出的反应性粘结机理,即反应性粘结剂PFR在交联过程中与不锈钢之间形成了C-O-Fe化学键,本章以PFR为反应性粘结剂,将Pt/C（Pt负载在Vulcan X C72R炭黑上）氧气还原反应（ORR）催化剂固定到金属集流体上,研究其在中性条件下的ORR电催化性能。研究了PFR的用量对其催化性能的影响,并与传统的Nafion粘结Pt/C催化剂（Pt/C-Nafion）的性能进行对比。结果表明,当PFR的用量减为标准用量的一半时（Pt/C-PFR-0.5）,由于其表面催化活性位点更多,其表现出与Pt/C-Nafion相当的ORR催化性能和更优异的长期稳定性。（4）反应性粘结纳米碳制备金属基生物膜载体及其微生物电化学反硝化性能研究。以反应性粘结纳米炭黑修饰的不锈钢丝球（CB/SS）作为导电生物膜载体,研究了其微生物电化学反硝化性能。导电生物膜载体上的微生物电催化活性测试结果表明,CB/SS载体上可自发形成同时具有微生物电催化氧化（有机物）和电催化还原（硝酸盐）反应活性的生物膜,即形成了微生物原电池（MGC）,强化了反硝化作用。将该方法用于修饰不锈钢污水输送管路,与传统聚氯乙烯管路相比,具有更好的反硝化性能。更多还原

【Abstract】 Microbial electrochemical technology（MET）has dual functions of energy generation and wastewater treatment.Thus,it can solve the problems of energy and environment to a certain extent.Metal materials,such as stainless steel,with excellent electrical conductivity and machinability,are commonly used as electrode materials and current collectors of microbial electrochemical system（MES）.However,metal materials can’t be directly used as anode materials due to the poor biocompatibility and the risk of corrosion.Surface modification is a common method to improve the biocompatibility and corrosion resistance of metal materials.In this paper,a metal surface modification strategy,namely reactive bonding nanocarbons is proposed to modify metal materials.On the one hand,high-performance metal-based bioanodes are prepared by this strategy to improve the biocompatibility and corrosion resistance.In addition,in order to further improve the performance of the metal-based bioanodes,mediators are introduced in the modification layer to enhance the electron transfer.On the other hand,this strategy is also used for the bonding of carbon-based oxygen reduction reaction（ORR）catalysts onto metal current collector for preparing ORR cathode.Finally,the reactive bonding nanocarbons modified stainless steel is used as the conductive biofilm carrier in the traditional biofilm wastewater treatment system to improve the performance of microbial electrochemical denitrification.The main contents are as follows:（1）Preparation of high-performance metal-based bioanodes by reactive bonding nanocarbons.The reactive binder（e.g.phenol formaldehyde resin,PFR）and nanocarbons（e.g.carbon black,CB）are used to prepare conductive dispersion（CB/PFR）for metal surface modification.Results of bonding strength test show that the bonding strength between the stainless steel and PFR is 5 times higher than that of Nafion.The excellent bonding strength is attributed to the reaction between PFR oligomer and metal（Me）during the process of thermal cross-linking,which results in the formation of C-O-Me bonds.The ratio of CB to PFR is optimized according to the results of ultrasonic striking and bioelectrocatalytic activity measurement.Results show that the coating with the CB mass ratio of 0.4（CB/PFR-0.4）possesses sufficient bond strength and excellent bioelectrocatalytic performance.For example,the modified stainless steel bioanode can generate a projected current density of 1.48 m A cm^-2,which is 1.6 times higher than that of the traditional graphite plate electrode.The corrosion resistance of metal-based bioanodes is improved by this reactive bonding modification strategy.In addition,this modification strategy can also applied to the commonly used metal materials（e.g.iron,copper,nickel and titanium）and different configurations（e.g.mesh,macro-channeled,foam and brush）to prepare high-performance metal-based bioanodes,and all of them show the similar bioelectrocatalytic performance.The honeycomb stainless steel bioanode with macro-channeled structure can generate a projected current density of 15 m A cm^-2,and the nickel foam bioanode achieved a volumetric current density of 78 m A cm^-3,which represent the highest values for metal-based bioanodes to date.Reactive bonding modification strategy is not confined to a certain reactive binder and conductive filler,the other reactive binders（e.g.melamine formaldehyde resin,MFR）and conductive fillers（e.g.carbon nanotubes,CNTs）modified metal-based bioanodes also show excellent bioelectrocatalytic performance,indicating this modified strategy has wide applicability.（2）Enhancing electron transfer by in-situ introduction of mediators on the surface of metal-based bioanodes.Based on the metal surface modification method in section（1）,carbon black is modified by thermal oxidation and nitric acid oxidation to introduce oxygen functional groups.Results of electrochemical test show that the carbon black oxidized at 500℃（CB-500）and oxidized in nitric acid solution（CB-N）have introduced a certain amount of quinone/phenol groups with an obvious redox pairs on the surface of the carbon black,which can act as mediators of indirect electron transfer by the conversion between quinone/phenol configurations.In addition,the results of electrical conductivity show that the electrical conductivity of CB-500 increased significantly due to partly removal of amorphous carbon in the process of thermal oxidation at high temperature.While,the electrical conductivity of CB-N decreased due to the introduction of excessive oxygen functional groups.Bioelectrochemical performance shows that the SS bioanode modified by CB-500achieves the best performance,which is 20%higher than that of the pristine CB modified SS bioanode.The improved performance is ascribed to the synergistic effect between the increase of electrical conductivity and the enhancement of indirect electron transfer by the quinone groups.This research shows that the simple thermal oxidation process of carbon black results in the improved bioelectrochemical performance of metal-based bioanodes by the increase of electrical conductivity and in situ introduction of quinone/phenol groups,which account for the enhancement of the direct electron transfer and indirect electron transfer,respectively.（3）Preparation of metal-based oxygen reduction cathode by reactive bonding carbon-based catalyst.Based on the results of the bonding strength analyzed in section（1）,a strong interaction is developed between SS and PFR binder.It can be attributed to the formation of C-O-Fe bonds between the PFR and the SS during the cross-linking process.In this section,PFR is used as the reactive binder to fix Pt/C（Pt supported on Vulcanx C72R carbon black）catalyst onto metal current collector to study its ORR electrocatalytic performance in neutral medium.The effect of the dosage of PFR on its catalytic performance is studied and compared with that bonded by the Nafion binder（Pt/C-Nafion）.Results show that the dosage of PFR binder in the Pt/C-PFR could be only half that of Nafion binder in the Pt/C-Nafion electrode,and the resulted Pt/C-PFR shows comparable ORR electrocatalytic performance and superior stability to that of Pt/C-Nafion electrode on the SS current collector.（4）Preparation of metal-based biofilm carrier by reactive bonding nanocarbons and its microbial electrochemical denitrification performance.Stainless steel wool modified by reactive bonding nanocarbons is used as the conductive biofilm carrier for studying the denitrification performance.Result of microbial electrocatalytic activity test on conductive biofilm carrier shows that the microbial galvanic cell（MGC）is formed on the CB/SS biofilm carrier,where catalytic oxidation and catalytic reduction reaction occured simultaneously,which results in the improvement of the denitrification performance.This method is applied in the sewage pipeline and shows better denitrification performance than PVC pipe.更多还原