Abstract
Understanding mass transfer processes concomitant with electrochemical conversion for gas evolution reactions at the electrode-electrolyte interface plays a key role in advancing renewable energy storage and conversion. However, due to the complicated diffusion behavior of gas at the dynamic catalytic interfaces, it is still a great challenge to accurately portray mass transfer of gas during electrocatalysis process. Here, we track the diffusion of dissolved oxygen on Cu nanostructured plasmonic interface, which reveals multistage oxygen diffusion behaviors, including premature oxygen accumulation, spontaneous diffusion and accelerated oxygen dissipation. This work uncovers an accumulating inhibition effect on oxygen evolution arising from interfacial dissolved oxygen. With these knowledges, we develop a programmable potential scan strategy to eliminate interfacial gas products, which alleviates the concentration polarization, releases accessible actives sites and promotes electrocatalytic performance. Our findings provide a direct observation of the interfacial mass transfer processes that governs the kinetics of gas-involved multiphases catalysis.
Highlights
Understanding mass transfer processes concomitant with electrochemical conversion for gas evolution reactions at the electrode-electrolyte interface plays a key role in advancing renewable energy storage and conversion
Conventional electrochemical measurements are incapable of in situ probing the oxygen diffusion behavior because of (i) severe concentration polarization induced by the increased chemical potential of dissolved gas molecules at the electrode interface and (ii) perturbations from non-Faradaic portion and concomitant side interfacial reactions at the electrode surface–liquid/gas diffusion layer, thereby unable to reveal the oxygen evolution dynamics at the EEIs
By taking advantage of the near-field enhancement, plasmonic-enhanced extinction spectroscopy provides an alternative way for real-time monitoring Oxygen evolution reaction (OER) and revealing oxygen profiles under polarization
Summary
Understanding mass transfer processes concomitant with electrochemical conversion for gas evolution reactions at the electrode-electrolyte interface plays a key role in advancing renewable energy storage and conversion. Gas evolution leads to an undesirable blockage of redox reaction sites and ion conducting pathways, resulting in an increase of ohmic resistance and formation of a heterogeneous concentration gradient at the EEIs7,8 All these effects give rise to energy losses and unfavorable attenuation of electrochemical conversion efficiencies. In situ spectroelectrochemical techniques[11,12,13], such as X-ray absorption/diffraction/scattering spectroscopy[14,15], infrared and Raman spectroscopy[16], mass spectrometry[17,18], and nuclear magnetic resonance[19], are powerful tools for identifying accessible catalytic active sites, adsorbed intermediates, and monitoring the reconstruction of electrocatalysts under operando conditions These approaches lack the ability of identifying fluctuations of interfacial dissolved oxygen due to the inherent negligible weak interaction between dissolved oxygen and the electrode surface. With the ability to deliver critical interfacial reaction information, the proposed strategy will provide in-depth information for understanding the intrinsic potential-dependent dynamic processes of various gas-involving systems at the EEIs
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