In Situ Characterization Of Surface Nanobubbles Based On Surface Plasmon Resonance Imaging

With the increasing environmental problems and energy shortages in recent years,clean energy represented by hydrogen energy has received more and more attention.Therefore,it is particularly important to study the gas involved reactions such as water splitting.In order to improve the working efficiency of the electrode,it is very important to study both the electrode material and the bubble behavior on the electrode surface.At present,the research on bubble behavior mainly focuses on macro scale bubbles,and the understanding of nanobubbles especially in the rapid growth stage after nucleation is not enough.The nanobubbles have unique properties such as high internal pressure and long life.When the nanobubbles are retained on the surface of the electrode,the bubble shielding effect is reduced to reduce the efficiency of the electrode,so it is necessary to study the nanobubbles.In order to solve the above problems,we build nanopoures gold electrode by pure Au electrode and observe bubble growth process by high speed camera.We also performed in-situ detection of nanobubbles generated on the electrode surface based on surface plasmon resonance imaging(SPRi).The specific research content and results are listed as follows:With the nanopoures gold electrode and observation of bubble growth process.It is found that the index of the radius changing with time on the surface of porous gold electrode is smaller than that on the flat electrode,but after the surface of porous gold electrode is degassed,some sites can continuously produce bubbles,while the flat electrode can only produce a few bubbles,probably due to the influence of nanobubbles.A chemical reaction and surface plasmon resonance imaging(EC-SPRi)device was set up,and the nanobubbles generated on the electrode surface during the HER reaction were in situ observed by the EC-SPRi device for the first time,and the nanobubbles on the electrode surface was assisted studied by atomic force microscopy.Combined with the data of the two instruments,it can be confirmed that the area on the SPRi image where the nanobubbles are generated will become brighter,and the brightness of the SPRi image and the size of reflectivity curve is positively correlated with the coverage of surface nanobubbles.By observing the change process of nanobubbles on the electrode surface based on EC-SPRi device,it is found that the coverage of nanobubbles on the electrode surface has an important influence on the anti-interference ability of nanobubbles.When the nanobubble coverage is less than 10%,the gas molecules in the nanobubbles easily flow out of the nanobubbles in the presence of interference,so that the nanobubbles cannot be stably existed and eventually disappear.When the nanobubble coverage of the electrode surface is greater than 10%,due to the high concentration of gas molecules on the surface of the electrode,the outward diffusion of gas molecules in the nanobubbles is limited,so the nanobubbles can remain stable.To verify the gas accumulation near the nanobubbles,control experiments were performed by flowing the prism surface with a pipette,combined with changes in reflectance and current,demonstrates.Besides,the relationship between nanobubble coverage and gas molecular layers was explored.The effect of wettability on the stability of surface nanobubbles was explored.In the presence of an aerophilic site,the gas-solid effect of the electrode surface is enhanced,and the nanobubbles are affected by the enhancement of gas-solidification,so that the efficiency of the outward diffusion of molecules inside the nanobubbles increases,and the nanobubbles cannot remain stable.So,the aerophilic area will not be covered by nanobubbles during reaction progresses.At the same time,the influence of the aerophilic ability and the number of aerophilic sites on the electrode was explored.And we infer that aerophilic/aerophobic pattern electrode is an important idea in the future electrode design.