In Situ Characterization Of Electrochemical Hydrogen Evolution Reaction Based On SPRI

For the ultilization of clean hydrogen energy,electrocatalysis is the keypoint of research.Optimization of the dynamics of gas bubble on the surface of electrode is also very important as well as the preparation of new materials.To date,the experimental study of bubble dynamics mainly relies on high-speed camera and atomic force microscope,which are still in lack of the accurate evolution informations of triphase contact line and contact area at gas/solid interface,and remains ambigous based on the estimation.Hence,seeking for an effective way to clearly capture and get deeper insight of the dynamics of gas bubble,is of great importance.Aiming to solve that problem,we develop a new "view from bottom"method to observe the bubble dynamics by taking hydrogen evolution electrocatalysis as the model reaction.The specific research content and results are listed as follows:1.According to the observation of electrode with different wettability for gas evolution reaction and gas consumption reaction,the informations of radius of bubbles and contact angle can be directly obtained.After the further calculation of the three phase contact line and the bottom area,we find that the radius-time evolution index of aerophobic surface(0.52)is slightly higher than that of the aerophilic surface(0.48).We preliminarily infer that the surface chemical potential and the supersaturation in aerophobic system are relative high,and the generated gas molecules diffuse along the surface of the whole bubble and inject into the bubble.While for the relatively aerophilic electrode,the surface chemical potential and the supersaturation are relatively low,and the electrogenerated gas molecules mainly diffuse along the bubble surface part near the electrode,resulting in the relative lower index(0.48).Therefore,it is also deduced that,the injection ratio of gas molecules into bubble will increase with the increase of the electrode aerophilicity,and induce the decrease of index.2.We develop a "view from bottom" technique based on surface plasmon resonance imaging to observe the change of bottom area of single bubble on platinum electrode surface with different wettability.The surface area of the hydrogen bubble on the aerophobic electrode increases gradually without obvious necking behavior,and the exponential of relationship between the the contact area change of the bubble and time is slightly less than the standard value of 1 because of the limited change of the contact angle.On the contrary,the contact area of hydrogen bubbles on the relative aerophilic electrode increases first and then decreases.Due to the relative unchanged contact angle of bubbles,the exponential of the relationship between the contact area and time is standard value of 1.Furthermore,interference-like fringe part in differential images of bubbles are indexed in to the reflection of lateral propagated evanescent wave.Therefore,surface plasmon imaging tecnique provide an effective way to accurately observe the dynamics of bubble from bottom,with huge potential for future bubble research.