<p>This study evaluated the performance of the
commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced
infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break
down a lot faster than anticipated which has serious implications on many
studies in the literature such as selectivity and kinetic analysis of the
electrocatalysts. Increasing electrolyte concentration, surprisingly, did not
extend the potential window of the phosphate buffers due to dramatic increase
in hydrogen evolution reaction. Even high concentration phosphate buffers (1
M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed
on copper electrodes. We have extended the discussion to high surface area
electrodes by evaluating electrodes composed of copper nanowires. We would like
highlight that it is not possible to cope with high local current densities on
these high surface area electrodes by using high buffer capacity solutions and
the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin
nanoparticle films onto inert substrates as commonly employed in fuel cell
reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction.
In addition, we underscore that normalization of the electrocatalytic
activity to the electrochemical active
surface area is not the ultimate solution due to concentration gradient along
the catalyst layer.This will “underestimate” the activity of
high surface electrocatalyst and the degree of underestimation will depend on
the thickness, porosity and morphology of the catalyst layer. </p>
<p> </p>
Comment on “High-surface-area corundum by mechanochemically induced phase transformation of boehmite”
