Design of a Graphene Nitrene Two-Dimensional Catalyst Heterostructure Providing a Well-Defined Site Accommodating One to Three Metals, with Application to CO₂ Reduction Electrocatalysis for the Two-Metal Case

Abstract

Recently, CO2 reduction to fuels has been the subject of great much numerous studies, but selectivity and activity remain inadequate. Progress has been made on single site twodimensional catalysts based on graphene coupled to a metal and nitrogen for CO2RR but the product is usually CO and the metal-N environment remains ambiguous. We report a novel 2D graphene-nitrene heterostructure (grafiN6) providing well-defined active sites (N6) that can bind 1 to 3 metals for CO2RR. We find that homo-bimetallic FeFe-grafiN6 could reduce CO2 to CH4 at -0.61 V and to CH3CH2OH at -0.68 V vs RHE, with high product selectivity. Moreover, the heteronuclear FeCu-grafiN6 system may be significantly less affected by HER, while maintaining low limiting potential (-0.68 V) for C1 and C2 mechanisms. Binding metals to one N6 site but not the other could promote efficient electron transport facilitating some reaction steps. This framework for single multiple metal sites might also provide unique catalytic sites for other catalytic process.

Carbon‐Supported Single Metal Site Catalysts for Electrochemical CO2 Reduction to CO and Beyond

“…The dual‐metal sites located adjacently on the same carbon substrate, which have been experimentally observed, could be regarded as a derivative structure of SACs. The Fe–Fe, [ 99 ] Fe–Cu, [ 100 ] and Ni–Co [ 101 ] based dual‐metal sites have been theoretically predicted to be active for electrochemical conversion of CO 2 into CO, HCOOH, CH 4 , and CH 3 CH 2 OH. The dual‐metal configurations can trigger unique synergetic interaction by tuning the electronic and geometric effects of active sites, which allows for alternative reaction paths to decrease the activation barriers of CO 2 RR.…”

Copper Dimer Anchored in g‐CN Monolayer as an Efficient Electrocatalyst for CO2 Reduction Reaction: A Computational Study

“…[ 18 ] Beyond SACs, double‐atom catalysts (DACs), in which transition metal dimers are anchored in suitable substrates, have recently emerged as extended family members in catalytic field due to double active sites and the corresponding synergetic catalytic effect. [ 21–32 ] Experimentally, He et al. successfully synthesized the Fe dimer embedded in the graphene with adjacent single vacancies.…”

“…[ 27 ] To achieve an excellent double‐atom catalyst, we not only need suitable transition metal atoms, but also need to deliberately select an appropriate substrate that can firmly interact with the transition metal atoms. Numerous 2D materials [ 21–32 ] have been investigated as promising substrates after the successful synthesis of graphene in 2004. [ 33 ] Introducing vacancies and holes in pristine graphene can overcome the drawbacks of desorption and aggregation of transition metal atoms.…”

Monitoring dynamics of defects and single Fe atoms in N-functionalized few-layer graphene by in situ temperature programmed scanning transmission electron microscopy

“…8a. Recently Chen et al [39], have indicated bimetallic graphene nitrene heterostructure FeFe-grafiN 6 systems as active sites for CO 2 reduction to multi-carbon products. The existence of this type of sites is also supported by our TEM analysis.…”