【作者】 刘琳；

【导师】 吴莉莉；

【作者基本信息】 山东大学 ， 材料与化工（专业学位）， 2025， 硕士

【摘要】 随着全球化石能源储备逐渐减少,燃油汽车的发展受到了越来越多的环境和资源限制,随之新能源汽车的应用正在日益广泛。但是近年来由新能源汽车锂离子电池热失控导致的火灾、爆炸事故频发,引起了广泛关注。研究表明电池早期热失控过程会产生大量气体如CO、CO2、烯烃类气体等,其中CO气体易燃易爆且有毒有害,如果能对CO气体浓度进行实时检测,便可以监控电池的状态,对电池热失控行为进行报警,为车内驾乘人员提供逃生时间。因此需要开发高灵敏、快速响应恢复的CO气体传感器。金属氧化物半导体(MOS)基气体传感器因具有易制备、成本低、体积小等优点而被广泛应用,但是仍然存在响应恢复速度较慢、灵敏度较低等问题。因此,本文以In2O3和ZnO为研究对象,通过异质结构建、离子掺杂和贵金属负载对其进行改性,获得了高灵敏度、低工作温度以及快速响应恢复的CO气体传感器。并通过XRD、SEM、TEM、XPS、霍尔效应测试等手段表征了材料的晶体结构、微观形貌及结构、表面化学状态及电学特性等,并结合气敏性能对其气敏机理进行了深入分析。本论文的主要研究内容如下:(1)通过两步水热法合成了 CuO负载的In2O3/InOOH纳米球,研究了 CuO负载对材料物相、氧物种相对含量以及气敏性能等的影响。研究表明,30%CuO-In2O3/InOOH在300 ℃下对100 ppm CO的响应值是纯In2O3的3.7倍,且具有快速的响应恢复速度(3/8 s-250 ppm CO)。与纯In2O3 相比,30%CuO-In2O3/InOOH 对浓度低至 800 ppb 的CO依然存在明显的响应且能够快速响应恢复(3/2s)。对其机理进行分析认为,优异的传感性能归因于CuO负载促进了部分In2O3相转变为InOOH相,提高氧空位含量,从而提供了更多活性位点。此外,CuO与In2O3/InOOH在界面处形成p-n异质结并产生额外的电子耗尽层,提高传感器的灵敏度。(2)通过水热法制备了碱金属Li离子掺杂的In2O3纳米球,获得了在较低工作温度下对CO气体具有高灵敏以及快速响应恢复的Li/In2O3传感器。研究表明,25Li/In2O3在80℃下对100 ppm CO的响应值高达287.5,且Li+掺杂后响应恢复时间明显缩短。对其机理进行分析认为,低价Li+掺杂高价金属氧化物In2O3后,为保持电中性,材料中的氧空位含量增加,促进活性氧物种形成并与CO气体发生气敏反应。此外,由于Li+与In1-2+发生氧化还原反应,使In1-2+失电子转化为In3+,使材料表面In3+/In1-2+比例增加从而呈现缺电子态,提高材料的可还原性,进而促进CO气敏反应的进行。通过In-situ DRIFTS分析可得Li+掺杂提高了 CO在材料表面的吸附速率,并减小了碳酸盐物种在材料表面吸附引起的“表面中毒”对气体吸附的抑制作用。(3)首先采用水热法制备了 ZnO纳米片,然后通过NaBH4还原氯金酸在其上原位生长Au纳米颗粒,调节了材料的能带结构以及电子耗尽层的宽度,获得了室温CO传感器。其中,0.10Au-ZnO样品在室温下对100 ppm CO的响应值可达139.75,是纯ZnO响应值(3.28)的43倍,且对CO气体能够实现快速响应以及完全恢复。对其气敏机理进行深入探究表明:Au纳米颗粒和ZnO纳米片由于功函数差异在其界面之间形成肖特基势垒而产生额外的电子耗尽层,不仅提高了传感器的灵敏度,还抑制了电子-空穴对的复合进而提高电荷转移效率。此外,通过UV-Vis测试证实了 Au纳米颗粒的SPR效应并通过COMSOL模拟材料表面的稳态感生电场分布和稳态温度分布进一步分析了SPR效应对材料表面的影响,并探究了其对气敏反应的促进作用。更多还原

【Abstract】 With the gradual depletion of global fossil fuel reserves,the development of gasolinepowered vehicles is facing increasing environmental and resource constraints.Meanwhile,the application of new energy vehicles is becoming increasingly widespread.However,in recent years,the frequent occurrence of fires and explosions caused by thermal runaway in lithiumion batteries of NEVs has raised widespread concern.Research indicates that during the early stages of battery thermal runaway,a large amount of gases such as CO,CO2,and alkene gases are produced.Among these,CO is flammable,explosive,toxic and harmful.If the concentration of CO can be detected in real-time,it would enable continuous monitoring of the battery’s status and provide early warnings for potential thermal runaway events,thereby providing valuable escape time to the occupants inside the vehicle.Therefore,there is a need to develop highsensitivity,fast-response CO gas sensors.Metal oxide semiconductor(MOS)based gas sensors are widely used due to their ease of fabrication,low cost,and compact size.However,they still face issues such as relatively slow response/recovery speeds and lower sensitivity,especially for CO sensing.Therefore,in this paper,In2O3 and ZnO are selected as the research subjects.By heterojunctions-constructing,ion-doping,and noble metals-loading,the materials were modified to achieve high sensitivity,low operating temperature and fast response/recovery for CO gas sensors.Characterization techniques such as XRD,SEM,TEM,XPS,and Hall effect measurements were employed to analyze the crystal structure,microstructure,surface chemical states,and electrical properties of the materials.Furthermore,based on the gas sensing performance,an in-depth analysis of the sensing mechanism was conducted.The main research of this paper is as follows:(1)The CuO-loaded In2O3/InOOH nanospheres were successfully synthesized using a two-step hydrothermal process.This study systematically explores the effect of CuO loading on the crystalline phase,the relative abundance of oxygen species,and its gas sensing performance.The study demonstrates that the 30%CuO-In2O3/InOOH composite exhibits a response value 3.7 times greater than that of pure In2O3 toward 100 ppm CO at 300℃ and shows impressive rapid response/recovery times(3/8 s to 250 ppm CO).Compared to pure In2O3,the 30%CuO-In2O3/InOOH composite shows a significant response to CO concentrations as low as 800 ppb,with rapid response/recovery(3/2 s).This indicates that the composite material has higher sensitivity and efficiency in detecting low concentrations of CO,making it suitable for applications requiring high-precision detection.An analysis of the mechanism suggests that the excellent sensing performance is attributed to the promotion of the partial transformation of the In2O3 phase into the InOOH phase by CuO loading.increasing the content of oxygen vacancy and providing more active sites.Additionally,a heterojunction is formed at the interface of CuO and In2O3/InOOH,creating an additional electron depletion layer.These effects collectively enhance the sensitivity of the sensor.(2)The Li-ion doped In2O3 nanospheres were prepared using a hydrothermal method,which resulted in a Li/In2O3 sensor that exhibits high sensitivity and rapid response/recovery characteristics towards CO gas at a relatively low operating temperature.It shows that the response of 25Li/In2O3 to 100 ppm CO reaches as high as 287.5 at 80℃,with shortened response/recovery time.An analysis of the mechanism suggests that the enhancement in gas sensing performance is attributed to the doping of low-valent Li+into high-valent meal oxides In2O3,to maintain electrical neutrality,the content of oxygen vacancies in the material is increased,promoting the formation of active oxygen species.Additionally,due to the redox reaction between Li+and In1-2+,In1-2+loses electrons and is oxidized to In3+.thereby increasing the In3+/In1-2+ratio on the material surface.This results in an electron-deficient surface,which enhances the material’s oxidizing ability and promotes the CO gas sensing reaction.Furthermore,through In-situ DRIFTS analysis,it was found that Li doping increases the adsorption rate of CO on the surface of materials and reduces the inhibitory effect of ’surface poisoning’ caused by the adsorption of carbonate species on the surface of materials,which would otherwise hinder gas adsorption.This further enhances the overall gas sensing performance of the material.(3)ZnO nanosheets were initially synthesized via a hydrothermal method,followed by the in-situ growth of Au nanoparticles on their surfaces through the reduction of chloroauric acid with NaBH4.This process adjusted the energy band structure of the material and the width of the electron depletion layer,resulting in room-temperature sensing of CO.At room temperature.the response value of 0.1 0Au-ZnO to 100 ppm CO is 139.75,which is 43 times higher than that of pure ZnO(3.28).Additionally,0.10Au-ZnO demonstrates rapid response and complete recovery towards CO.An in-depth investigation into the gas sensing mechanism reveals that the difference in work function between Au nanoparticles and ZnO nanosheets results in the formation of a Schottky barrier at their interface.generating an additional electron depletion layer.This not only enhances the sensor’s sensitivity but also suppresses the recombination of electron-hole pairs.thereby improving charge transfer efficiency.Furthermore,UV-Vis testing confirmed the Surface Plasmon Resonance(SPR)effect of Au nanoparticles.Through COMSOL simulations of the steady-state induced electric field distribution and steady-state temperature distribution,the impact of the SPR effect on the surface of materials was analyzed.And further explored how the SPR effect promotes gas sensing reactions.更多还原