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Title: Origin of alkali cation effects in electrochemical CO2 reduction
Plain: On copper and gold electrodes, CO2 reduction barely works without metal cations in the solution, and larger cations such as cesium work better than lithium. Why the cation matters so much is unsettled.
Precise: For CO2 reduction on Cu and Au electrodes in aqueous MHCO3 ($M = \mathrm{Li}, \mathrm{Na}, \mathrm{K}, \mathrm{Cs}$), identify the mechanism by which the cation controls the rate of the first CO2 activation step and the product selectivity: interfacial field stabilization of adsorbed $\mathrm{CO2}-$, direct coordination, local buffering of pH, or modification of the hydrogen-bond network. An answer is a model predicting partial current densities versus cation identity and concentration.
Settled by: Spectroscopic detection of cation-adsorbate interactions combined with explicit-cation constant-potential simulations that reproduce the measured trends.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: contested
Status note: (empty)
Posed since: (empty)