“…Ad rastic increase in faradaic selectivity of one order-of-magnitude for both formate and acetate is observed, with total carbon selectivity above 95 %. Even if acetate has been considered deriving from furtherr eactions throughc oupling processes from the formed species with one carbon atom, [63][64][65] the trendso bservedi nF igure 4d on ot indicate ac onsecutive, but ap arallel path for the two products.T he hydrogen production reaches the highera mount in the first 1hof CO 2 electroreduction,d ecreasingw ith time. Note that in the first hour,h owever,t here is not an increase in the rate, but an apparent effect relatedt o the accumulation of the H 2 in the empty volumeo ft he gas phase system of the electrocatalytic reactor.B eing this side reaction of H 2 formation mainly due to the GDL itself, as commented before,i ti sr easonable to indicate that the active sites responsible of this side reaction are progressively inhibited, www.chemsuschem.org likely by CO 2 strong chemisorption.…”