This tutorial review elucidates how to design catalytically active sites for efficient and highly selective photocatalytic reduction of CO2 by learning from conventional CO2 hydrogenation and syngas conversion.
CO2 electroreduction to high-energy-density C2+ products
is highly attractive, whereas the C2+ selectivity
under industrial current densities is still unsatisfying. Here, an
anti-swelling anion exchange ionomer (AEI) was first proposed to optimize
the local environment for promoting industrial-current-density CO2-to-C2+ electroreduction. Taking the anti-swelling
AEI-modified oxide-derived Cu nanosheets as an example, in
situ Raman spectroscopy and contact angle measurements revealed
that the OH–-accumulated -N(CH3)3
+ groups and anti-swelling backbone of AEI could
synergistically regulate the local pH level and water content. In situ Fourier-transform infrared spectroscopy and theoretical
calculations demonstrated that the higher local pH value could lower
the energy barrier for the rate-limiting COCO* hydrogenated to COCOH*
from 0.08 to 0.04 eV, thereby boosting the generation of C2+ products. Owing to the anti-swelling backbone, the optimized water
content of 3.5% could suppress the competing H2 evolution
and hence facilitate the proton-electron transfer step for C2+ production. As a result, the anti-swelling AEI-modified oxide-derived
Cu nanosheets achieved a C2+ Faradaic efficiency of 85.1%
at a current density up to 800 mA cm–2 with a half-cell
power conversion efficiency exceeding 50%, outperforming most reported
powder catalysts.
Structural reconstruction is a process commonly observed for Cu‐based catalysts in electrochemical CO2 reduction. The Cu‐based precatalysts with structural complexity often undergo sophisticated structural reconstruction processes, which may offer opportunities for enhancing the electrosynthesis of multicarbon products (C2+ products) but remain largely uncertain due to various new structural features possibly arising during the processes. In this work, the Cu2O superparticles with an assembly structure are demonstrated to undergo complicated structure evolution under electrochemical reduction condition, enabling highly selective CO2‐to‐C2+ products conversion in electrocatalysis. As revealed by electron microscopic characterization together with in situ X‐ray absorption spectroscopy and Raman spectroscopy, the building blocks inside the superparticle fuse to generate numerous grain boundaries while those in the outer shell detach to form nanogap structures that can efficiently confine OH− to induce high local pH. Such a combination of unique structural features with local reaction environment offers two important factors for facilitating C−C coupling. Consequently, the Cu2O superparticle‐derived catalyst achieves high faradaic efficiencies of 53.2% for C2H4 and 74.2% for C2+ products, surpassing the performance of geometrically simpler Cu2O cube‐derived catalyst and most reported Cu electrocatalysts under comparable conditions. This work provides insights for rationally designing highly selective CO2 reduction electrocatalysts by controlling structural reconstruction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.