Visualization of the Key Proton Activities in Hydrogen Evolution Reaction by Electrochromic Catalyst

The electrocatalytic hydrogen evolution reaction (HER) is a promising route to produce sustainable hydrogen energy carrier for global carbon neutrality. The HER performance is largely determined by the overall proton activities, but the identification of such key proton activities in microscopic HER process is rather difficult. Herein, the study demonstrates a visualized HER concept by integrating the fundamental HER process with electrochromic technology on a well-designed Pt@WO₃ platform in acidic electrolyte, where the overall proton activities in HER process can be rapidly discriminated by the color changes of Pt@WO₃ electrochromic electrode. In contrast to bare WO₃ counterpart, the Pt@WO₃ electrochromic electrode displays a rather more positive potential of initial-coloration state and faster decoloration rate associated with significantly improved reaction kinetics of hydrogen intercalation and deintercalation within WO₃ component. Correspondingly, the as-prepared Pt@WO₃ catalyst electrode exhibits a remarkable HER activity with a lower onset-potential (45 mV, proton adsorption and accumulation) and smaller Tafel slope (50 mV dec^-1, proton desorption), nearly 11.1- and 3.5-fold enhancement than those of bare WO₃ counterpart. It is believed that the work in integrating the interesting visualization functionality into fundamental HER process may improve the readability of such microscopic electrocatalytic reaction and advance the exploration of more intelligent electrocatalysts.