Structural Sensitivities in Bimetallic Catalysts for Electrochemical CO₂ Reduction Revealed by Ag–Cu Nanodimers

Abstract

Understanding the structural and compositional sensitivities of the electrochemical CO2 reduction reaction (CO2RR) is fundamentally important for developing highly efficient and selective electrocatalysts. Here, we use Ag/Cu nanocrystals to uncover the key role played by the Ag/Cu interface in promoting CO2RR. Nanodimers including the two constituent metals as segregated domains sharing a tunable interface are obtained by developing a seeded growth synthesis, wherein preformed Ag nanoparticles are used as nucleation seeds for the Cu domain. We find that the type of metal precursor and the strength of the reducing agent play a key role in achieving the desired chemical and structural control. We show that tandem catalysis and electronic effects, both enabled by the addition of Ag to Cu in the form of segregated nanodomain within the same catalyst, synergistically account for an enhancement in the Faradaic efficiency for C2H4 by 3.4-fold and in the partial current density for CO2 reduction by 2-fold compared with the pure Cu counterpart. The insights gained from this work may be beneficial for designing efficient multicomponent catalysts for electrochemical CO2 reduction.

Rational Design of Ag‐Based Catalysts for the Electrochemical CO2 Reduction to CO: A Review

“…It was also reported that structure, morphology, size, and composition of the catalyst can lead to adsorption and decoupling site preferences of different adsorbates of C bound on the surface and further result in the breaking of the linear scaling relationships and tuning of the adsorption strength, eventually exerting a dramatic influence on the ECR performance . Indeed, in addition to polycrystalline and single‐crystalline Ag, some new A types have been developed and characterized recently, such as nanostructured Ag with different sizes, supported Ag catalysts with different substrates including C, TiO 2 , Al 2 O 3 , dopant‐aided Ag, oxide‐derived Ag, and surface‐modified Ag …”

“…Interestingly, although CO is the predominant reaction product for Ag–Cu in the selective ECR, which is derived mainly from synergistic reactions rather than pure dilution effects between Ag and Cu, it should be noted that Cu and Cu‐based catalysts including Ag–Cu also have the potential to convert CO 2 to various hydrocarbons such as C 2 H 6 , CH 4 , or/and oxygenates such as C 2 H 5 OH, CH 3 OH, HCHO . Further studies demonstrated that the selectivity and activity of these bimetallic Ag–Cu electrocatalysts for the ECR to CO were closely related to the atomic distributions and ratios of Ag and Cu …”

“…[69,76] It was also reported that structure, morphology,s ize, and compositionoft he catalystcan lead to adsorption and decoupling site preferences of different adsorbates of Cb ound on the surfacea nd further result in the breakingo ft he linear scaling relationships and tuning of the adsorption strength, eventually exertingadramatici nfluence on the ECR performance. [69,77,78] Indeed, in addition to polycrystalline and single-crystalline Ag, some new At ypes have been developed and characterized recently,s uch as nanostructured Ag with different sizes, [79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94] supported Ag catalysts with different substrates including C, TiO 2 ,A l 2 O 3 , [95][96][97] dopant-aided Ag, [98-120, 129, 130] oxide-derived Ag, [121][122][123][124][125][126][127][128] and surface-modified Ag. [131][132][133][134] In principle, the reduction of NP size can enhancet he surface reactivity of nanomaterials by either directly affecting the atomic arrangement, such as ratio of the atoms at the edge, corner, or surface, or amplifying the effects of other structural factors such as defects, resulting in the tuning of BEs of intermediates and transition states on catalyst surfaces.…”

Superior Selectivity and Tolerance towards Metal‐Ion Impurities of a Fe/N/C Catalyst for CO2 Reduction

“…Inevitably,i ti sa lso influenced by the pH of the electrolyte. [35] The FE for CO productiono ver SMFeSCN reached approximately9 9% at À0.55 V, whereas that over SMFe reached only 87 %a tt he same potential. To furtherc onfirmt he CO 2 RR performance, the liquid phase after 3hreactionw as investigated by 1 HNMR spectroscopy,b ut no products were detected,a ss hown in Figure S2 in the Supporting Information.…”

“…The FE of gaseous productsw as calculated by GC analysis. [35] The FE for CO productiono ver SMFeSCN reached approximately9 9% at À0.55 V, whereas that over SMFe reached only 87 %a tt he same potential. Furthermore, over aw ide range of potentials from À0.45 to À0.85 V, ah igh FE for CO productiono verS MFeSCN (!…”