银纳米片自组装有序电极的制备、表面增强拉曼效应及氧还原反应机理研究

INVESTIGATION ON OXYGEN REDUCTIONREACTION BASED ON THE SURFACEENHANCED RAMAN EFFECT OF ORDERDSILVER ELECTRODE ASSEMBED FROM SILVERNANOSHEETS

王冰雪

11749114

硕士

材料科学与工程

卢周广

2019-06-01

2019-07-13

哈尔滨工业大学

深圳

表面增强拉曼光谱（ SERS） 作为一种高灵敏度的痕量检测工具已经被各个领域广泛应用， 而在金属空气电池、 燃料电池中起着重要作用的氧还原过程长期以来一直是电化学研究的焦点。 氧还原过程中的电子得失以及每一过程出现的中间态， 得到了人们的广泛研究。 本文将表面增强拉曼光谱（ SERS） 引入到氧还原过程中中间产物的检测， 实现了对氧还原过程中间产物原位实时的检测。本文通过电化学沉积的方法制备了有序的银纳米片结构基底， 实验发现通过改变电流的密度可以对纳米片的厚度进行调控进而调控基底的拉曼增强性能。 当电流密度为 0.25mA/cm2 时， 所获得的基底灵敏度很高、 拉曼增强性能最佳。 之后基于所得的最优的拉曼增强基底， 采用 ALD 的方法对有序纳米片结构进行包覆， 使其具有很好的热稳定性和抗氧化、 硫化的性质。 考虑到 ALD 对材料的热稳定性和拉曼增强的影响， 最终选择 ALD 两个循环的基底作为最优的材料， 对材料进行拉曼增强性能的检测， 证明所得基底材料能够进行多种探测分子检测以及用于检测浓度很低的探测分子溶液， 达到了痕量检测的目的。 基底的可循环性能测试也证明了材料具有很高的熔点， 能够在高温热清洁过程中不发生微结构的融化等， 很大程度上保持了基底的拉曼增强性能以此达到了重复利用的效果。 这一基底的合成很大程度上解决了传统意义上的贵金属纳米颗粒易团聚、 难保存等缺点。由于电化学反应过程中的中间产物具有快速转变且浓度低等特点， 用传统意义上的拉曼很难检测到。 制备出的银纳米材料具有很强的拉曼增强性能兼电催化活性， 因此能够原位捕捉到氧还原过程中的中间产物。 在这一氧化原反应双电子过程中， 我们成功检测到了在氧还原反应初期 O2 得到一个电子产生的O2-， 以及当电流持续增大时， O2 得到两个电子之后的过氧化合物 HO2-也成功被检测到。 这一基底的使用有效排除了增强基底吸附中间态物质过程中发生的滞后等情况。 因此， 这一基底对于一个双电子的催化剂氧还原反应的过程的研究有着重要的指导意义。

Surface-enhanced Raman spectroscopy (SERS) has been widely used as ahigh-sensitivity trace detection tool in various fields. The oxygen reduction process,which plays an important role in metal-air batteries and fuel cells, has long been thefocus of electrochemical research. The electron gain and loss in the oxygenreduction process and the intermediate state in each process have been widelystudied. In this paper, surface-enhanced Raman spectroscopy (SERS) wasintroduced into the detection of intermediates in the oxygen reduction process,real-time detection of the intermediate products in the oxygen reduction process wasrealized.Ordered silver nanosheets structure substrate was prepared by electrochemicaldeposition. It turns out that changing the density of the current can regulate thethickness of the nanosheet and thereby adjust the SERS property of the substrate.When the current density is 0.25 mA/cm2, the obtained substrate has excellentsensitivity and the SERS performance is optimal. Then, The ordered nanosheetsstructure is coated by ALD method, which has distinguished thermal stability andoxidation resistance and vulcanization properties. Considering the impact of ALDon the thermal stability and SERS activity of the material, the substrate of twocycles ALD was finally selected as the optimum material. The Raman enhancementperformance of the material is tested, and the obtained substrate material can beused for detecting a plurality of detection molecules and detecting a lowconcentration of the probe molecule solution, thereby achieving the purpose of tracedetection. The cyclability test of the substrate also proves that the material has ahigh melting point, the microstructure of substrate during high-temperature thermalcleaning can be maintained, thus, largely maintains the Raman enhancement of thesubstrate to achieve reuse. The emergence of this substrate largely solves thedisadvantages of the precious metal nanoparticles which are easy to agglomerate anddifficult to preserve in the traditional sense.Due to the rapid transition and low concentration of the intermediate productsin the electrochemical reaction process, it is difficult to detect with traditionalRaman. The prepared silver nanomaterial has strong Raman enhancementperformance and electrocatalytic activity, so that the intermediate products in theoxygen reduction reaction (ORR) process can be captured in situ.In this oxidative reaction two-electron process, we successfully probed the O2-produced by O2 obtaining an electron in the initial stage of ORR. when the currentcontinues to increase, the peroxy compound HO2- generated after O2 has obtained two electrons is also successfully detected. The success of this substrate effectivelyavoids the influence of Raman-enhanced substrate materials on the catalytic reactionof the catalyst in the electrocatalytic process, and eliminates the hysteresis thatoccurs during the process of substrate adsorbing intermediate substances. Therefore,the synthesis of this substrate has important guiding significance for the study of theprocess of a two-electron catalyst ORR.

表面增强拉曼光谱 电催化 氧化原反应 热清洁基底 Ag 纳米材料 半导体薄膜

Surface-enhanced Raman Scattering electrocatalysis oxidative reaction heat cleaning substrate Ag nanomaterial semiconductor film

中文

联合培养

南方科技大学

王冰雪. 银纳米片自组装有序电极的制备、表面增强拉曼效应及氧还原反应机理研究[D]. 深圳. 哈尔滨工业大学,2019.