Cobalt(II) tetraphenylporphyrin trapped in the pores of Cu2O to enhance the C2+ selectivity towards acidic CO2 electroreduction

Abstract

Achieving the high selectivity of multicarbon (C2+) products during the acidic CO2 electroreduction remains a formidable challenge due to the serious hydrogen evolution reaction. Herein we report a Cu-based tandem catalyst by implanting molecular cobalt(II) tetraphenylporphyrin (CoTPP) into a porous Cu2O (Cu2O-CoTPP) for improving the C2+ selectivity in acidic media. Specially, CoTPP, as a CO-selective catalyst, is predominantly trapped in the nanopores of Cu2O with the assistance of negative-pressure ultrasonic. The CO2-CO and CO-C2+ tandem catalysis on Cu2O-CoTPP, cooperating with the pore confinement effect of porous Cu2O, boosts the local CO concentration and *CO coverage on Cu sites, evidenced by in-situ Raman spectra and finite element simulations. As a result, Cu2O-CoTPP attains a C2+ Faradaic efficiency of 91.2 % at an industrial-level current density of 800 mA/cm2 in an acidic environment (pH = 1.9), higher than the one (70.6 %) on pristine Cu2O. Meanwhile, such a tandem catalyst obtains a high single-pass carbon efficiency of 52.6 % and the good catalytic stability of at least 20 h. This study offers a spatially-confined Cu-based tandem catalyst for selective C2+ production, presenting the promising application in acidic environments.