Delocalization state-induced selective bond breaking for efficient methanol electrosynthesis from CO2
Methanol manufacturing by CO 2 electrolysis is a potential near-zero-emission route to carbon neutrality, but most of the previous studies in aqueous electrolytes have achieved poor methanol selectivity and yield. Inspired by hard–soft acid–base theory, we proposed that the CO 2 electroreduction pathways towards methanol or methane could be switched by tuning the electron delocalization state of Cu catalytic sites. On the basis of this hypothesis, we have designed and synthesized a cuprous cyanamide (Cu 2 NCN) crystal in which isolated Cu(I) ions strongly conjugated with NCN 2− exhibit highly delocalized electrons. Theoretical calculations showed that Cu 2 NCN substantially reduces the Cu–O interaction of the adsorbed *OCH 3 intermediate so that it is weaker than the O–C interaction at the critical reaction bifurcation point of Cu‒*O‒CH 3 , thus switching the pathway to release *OCH 3 and form methanol. The Cu 2 NCN catalyst exhibits one of the highest recorded CO 2 -to-CH 3 OH selectivities (70%) and an outstanding partial current density of −92.3 mA cm −2 in aqueous electrolyte, corresponding to a CH 3 OH electroproduction rate of 0.160 μmol s −1 cm −2 .
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