Electrocatalysis is quite heterogeneous, both in electron transfer and surface catalytic processes. Understanding how applied voltage drives the electrocatalytic reaction at the nanoscale is a fundamental scientific problem. The problem becomes rather complex in nonmetallic catalysts due to their low intrinsic carrier concentration and complex chemical composition. Herein, using monolayer MoS2 as a model system of nonmetallic catalyst, the potential distribution between the basal plane of MoS2 (ΔVch) and the electric double layer (ΔVedl) were decoupled quantitatively as a function of applied voltage through in-situ surface potential microscopy. We visualized the evolution of the band structure under liquid conditions and clarified the process of EF keeping moving deep into Ec. The deep state of EF causes high surface electron concentration (over 1 × 1013 e cm−2) on the basal plane under electrolyte conditions. Nanoscale imaging of electron transfer (ET) and the surface catalytic processes revealed that the basal plane exhibits high ET activity comparable to the edge but inert catalytic activity. In this case, the applied voltage plays an essential role in the ET process of the basal plane by increasing the surface electron concentration by five orders of magnitude, but cannot be accurately applied on the catalytic site due to the spatial mismatch of ET and reactant adsorption sites. We provide a method for studying electrochemical driving force at the nanoscale and demonstrate that the driving force (voltage) can be accurately applied to the electrocatalytic sites only when the electron transfer site and the chemical site are spatially coincident.

Visualizing the role of applied voltage in non-metal electrocatalyst

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.