Ni-Electrocatalytic CO Reduction Toward Ethanol.

The electroreduction of CO offers a sustainable route to generate synthetic fuels. Cu-based catalysts have been developed to produce value-added C alcohols; however, the limited understanding of complex C-C coupling and reaction pathway hinders the development of efficient CO-to-C alcohols catalysts. Herein, a Cu-free, highly mesoporous NiO catalyst, derived from the microphase separation of a block copolymer, is reported, which achieves selective CO reduction toward ethanol with a Faradaic efficiency of 75.2% at -0.6 V versus RHE. The dense mesopores create a favorable local reaction environment with CO-rich and HO-deficient interfaces, suppressing hydrogen evolution and maximizing catalytic activity of NiO for CO reduction. Importantly, the C-feeding experiments, in situ spectroscopy, and theoretical calculations consistently show that the direct coupling of *CO and *COOH is responsible for C-C bond formation on NiO, and subsequent reduction of *CO-COOH to ethanol is energetically facile through the *COCOH and *OCH pathway. The unconventional C-C coupling mechanism on NiO, in contrast to the *CO dimerization on Cu, is triggered by strong CO adsorption on the polarized Ni-O sites. The work not only demonstrates a highly selective Cu-free Ni-based alternative for CO-to-C alcohols transformation but also provides a new perspective on C-C coupling toward C synthesis.