Selective C-C Coupling by Spatially Confined Dimeric Metal Centers.

Yanyan Zhao,Si Zhou,Jijun Zhao

doi:10.1016/j.isci.2020.101051

Abstract

SummaryDirect conversion of carbon dioxide (CO2) to high-energy fuels and high-value chemicals is a fascinating sustainable strategy. For most of the current electrocatalysts for CO2 reduction, however, multi-carbon products are inhibited by large overpotentials and low selectivity. Herein, we exploit dispersed 3d transition metal dimers as spatially confined dual reaction centers for selective reduction of CO2 to liquid fuels. Various nitrogenated holey carbon monolayers are shown to be promising templates to stabilize these metal dimers and dictate their electronic structures, allowing precise control of the catalytic activity and product selectivity. By comprehensive first-principles calculations, we screen the suitable transition metal dimers that universally have high activity for ethanol (C2H5OH). Furthermore, remarkable selectivity for C2H5OH against other C1 and C2 products is found for Fe2 dimer anchored on C2N monolayer. The role of electronic coupling between the metal dimer and the carbon substrates is thoroughly elucidated.

Highlights

Production of liquid fuels by catalytic convertion of CO2, the main greenhouse gas and an abundant carbon feedstock, has been regarded as an appealing strategy to solve both energy and environmental crises, albeit facing great challenges (Birdja et al, 2019; Jia et al, 2019; Amal et al, 2017)
We focused on pyridine N dopants in graphene, which are the main doping species at high N contents and are usually associated with the vacancies or pores of the carbon basal plane (Sheng et al, 2011; Sarau et al, 2017)
Note that the V6 pore in graphene is a favorable defect according to transmission electron microscopy experiment (Robertson et al, 2015), and our previous calculation showed that N-doped V6 has extraordinary thermodynamic stability (Luo et al, 2013)

Summary

Introduction

Production of liquid fuels by catalytic convertion of CO2, the main greenhouse gas and an abundant carbon feedstock, has been regarded as an appealing strategy to solve both energy and environmental crises, albeit facing great challenges (Birdja et al, 2019; Jia et al, 2019; Amal et al, 2017). Fairly good activity can be achieved by modification or morphology engineering of copper, such as sculpturing it into nanoparticles or nanocubes, doping or alloying, and making oxide-derived copper, the selectivity and efficiency of most copper-based electrocatalysts remain unsatisfactory for commercialization of the CO2 conversion technique to high-energy fuels and high-value chemicals (Gao et al, 2019; Kim et al, 2017; Wang et al, 2018; Zhou et al, 2018). Transition metal atoms dispersed on nitrogen-doped porous carbon nanomaterials emerge as a promising category of electrocatalysts for CO2 reduction, which have maximum atomic efficiency, high electrical conductivity and good durability, and can be facilely synthesized in the laboratory (Bayatsarmadi et al, 2017; Chen et al, 2019; Cheng et al, 2018; Wang et al, 2019). The single metal sites have an advantage of suppressing the competing hydrogen evolution reaction (HER), due to the unique adsorption configuration of H* species compared with those on the transition metal surfaces (Bagger et al, 2017)

Methods

Results

Conclusion