Recent Advances of Single‐Atom‐Alloy for Energy Electrocatalysis

Abstract

In another example, intermetallics featuring smaller Pt [ , 8] Pd, [9] and Ir [10] atomic ensembles displayed higher formic acid oxidation reaction (FAOR) activity compared with corresponding monometallic nanoparticles. Thus, alloying is a feasible strategy to promote electrocatalytic performances. However, the random bimetallic alloy catalysts exhibit multiple types of atomic configurations, making it difficult to distinguish the most active coordination environment. In addition, the atomic utilization of noble metals, which usually working as the active sites, needs to be further promoted for common alloy catalysts.To achieve a full utilization of metallic atoms, single-atom catalysts (SACs) were developed in recent years. [11] Moreover, the significantly changed adsorption properties render SACs highly active in several reactions in which the metallic catalysts are inactive. For example, Fe, [12] Co, [13] Zn, [14] etc. SACs displayed superior ORR activity, enabling SACs promising cathodic catalysts in fuel cells. In the anodic reactions, Rh-N-C [15] and Ir-N-C [16] SACs exhibit ultrahigh FAOR activity surpassing state-ofthe-art Pd catalyst, while Rh and Ir nanoparticles are almost inert. Although SACs offer a full expose of metal sites, tuning the intrinsic activity is highly dependent on the substrates which anchored the single atomic sites. For instance, N-doped C anchored Pt SAC [16] displayed inferior FAOR performance while Au nanoparticles supported single atomic Pt [17] delivered excellent catalytic selectivity and activity, which may be attributed to the varying electronic structures of Pt. In view of the full utilization of active atoms in SACs and synergetic effects in alloys, combining their merits represents one of the most promising strategies to further promote electrocatalytic performance and acquiring structure-activity relationship in specific coordination environments. Thus, single-atom-alloys (SAAs), featuring with atomically dispersed metallic dopant atoms on the surface of metal hosts, [18] have been a kind of promising catalysts in heterogeneous catalysis. Commonly, the dopant atoms are active for specific reactions while the host metals are less reactive.The dopant element in SAA exhibits a free-atom-like electronic structure compared with host metal elements. [19] As shown in Figure 1a, the host metal Au exhibited the broad d-project density of states (DOS), while the dopant elements Pt and Ni exhibited the narrow d-project DOS, similar to the free-atom-like electronic states. Up to now, Pt-group metals are mainly employed as the dopants in SAAs to promote the Single-atom-alloys (SAAs), as an emerging kind of materials, combine the advantages of alloy and single-atom catalysts. The full atomic utilization of active sites and well-defined bonding environments in SAAs lead to superior electrocatalytic performance and give a deep insight into the structural-activity relationship. In this review, the recent advances of SAAs in various electrochemical reactions are highlighted for further...

Rational design of atomic site catalysts for electrochemical CO2reduction

“…131 In addition to oxide-supported ASCs, single-atom alloys are composed of foreign atoms diluted in a host metal matrix, with special electronic and geometric characteristics distinct from their constituent metals. 133,134 These unique properties can endow SAAs with distinct catalytic properties. For instance, Zheng et al synthesized a Pb-alloyed Cu catalyst by introducing Pb single atoms into the surface of metallic copper (denoted Pb 1 Cu).…”

Ordered and Isolated Pd Sites Endow Antiperovskite‐Type PdFe3N with High CO‐Tolerance for Formic Acid Electrooxidation

“…[ 27,28 ] In particular, intrinsically isolated single atomic sites on alloy surfaces have been proven to possess superior CO tolerance because continuous active sites are segregated by host metal. [ 29–33 ] However, for the widely studied Pd‐based alloys (solid solution), it is a great challenge to precisely control the isolated single atomic sites due to the random distribution of Pd and the second metal over the Wycoff atomic positions. Moreover, the disordered Pd–M alloys (M = transition metal) suffer from the etching of M in a harsh acid environment and present unsatisfactory stability.…”

Asymmetric Coordination Environment Engineering of Atomic Catalysts for CO2 Reduction

“…For traditional bulk and/or nanoparticles (NPs) electrocatalysts, only a few layers of the atoms on the surfaces of the catalysts are involved in the reactions, resulting in a large percentage of the metal atoms being ineffective and wasted. Consequently, next-generation electrocatalysts need to meet the strict demands of higher atomic utilization efficiency compared with the original ones [ 29 , 30 , 31 , 32 ].…”