Free-atom-like d states in single-atom alloy catalysts

Abstract

Alloying provides a means by which to tune a metal catalyst's electronic structure and thus tailor its performance; however, mean-field behaviour in metals imposes limits. To access unprecedented catalytic behaviour, materials must exhibit emergent properties that are not simply interpolations of the constituent components' properties. Here we show an emergent electronic structure in single-atom alloys, whereby weak wavefunction mixing between minority and majority elements results in a free-atom-like electronic structure on the minority element. This unusual electronic structure alters the minority element's adsorption properties such that the bonding with adsorbates resembles the bonding in molecular metal complexes. We demonstrate this phenomenon with AgCu alloys, dilute in Cu, where the Cu d states are nearly unperturbed from their free-atom state. In situ electron spectroscopy demonstrates that this unusual electronic structure persists in reaction conditions and exhibits a 0.1 eV smaller activation barrier than bulk Cu in methanol reforming. Theory predicts that several other dilute alloys exhibit this phenomenon, which offers a design approach that may lead to alloys with unprecedented catalytic properties.

Ruthenium‐Based Single‐Atom Alloy with High Electrocatalytic Activity for Hydrogen Evolution

“…[17,[19][20][21] Many efforts had been devoted to constructing Rubased heterostructures (e.g., Ru/carbon quantum dots, [22] Ru/C 2 N, [18] RuCo/ nitrogen-doped graphene, [23] fcc-Ru/ C 3 N 4 /C, [17] Ru/nitrogen-doped carbon, [24] Ru/graphene [25] ), which show great advantages on promoting water dissociation by synergistic effect. [23,26,27] meanwhile, the interaction between the solute atoms and matrix can modify their electronic structure, [26,28,29] leading to a suitable adsorption energy for hydrogen. Recently, singleatom alloys (SAAs), which comprise separated solute atoms in metallic matrix, show great potential on circumventing scaling relationships.…”

N,P Co‐Coordinated Manganese Atoms in Mesoporous Carbon for Electrochemical Oxygen Reduction

“…Interestingly, a slight shift of the main L 3 peak can be observed in the MnNPC‐900 in comparison with that of the MnNC‐900 in Figure e. This negative shift can be attributed to the P coordination with Mn sites, which consequently leads to further modification of electronic structure of Mn atoms . The results may indicate that P atoms are coordinated with Mn atoms, forming new MnN x P y active complex.…”

Mono‐/Multinuclear Water Oxidation Catalysts

“…Some highly dispersed metal-supported WOCs can be synthesized through chemical reduction. [15] The mass-selected soft-landing method can also be applied to synthesize WOCs. [41] In addition, Das [43] Additionally,abinuclear Mn-based catalyst, [(terpy)(SO 4 )Mn IV (O) 2 Mn IV (O 4 S)(terpy)] (terpy:2 ,2':6',2''-terpyridine) can also be synthesized by using MnSO 4 and terpy as the precursors and potassium peroxomonosulfate as the oxidant.…”

“…[15] Compared with Cu, the 3d band in Cu atoms supported on Ag (AgCu) is extremelyn arrow.A dditionally,t he Cu 3d band in AgCu is symmetric, which demonstratest hat there is an extremely weak interaction between Cu atoms and surrounding elements, and the Cu 3d band in Cu is not only wider than that in AgCu, but also asymmetric, which demonstrates that there is ac lear orbital interaction between the Cu atom and surrounding elements. [15] Compared with Cu, the 3d band in Cu atoms supported on Ag (AgCu) is extremelyn arrow.A dditionally,t he Cu 3d band in AgCu is symmetric, which demonstratest hat there is an extremely weak interaction between Cu atoms and surrounding elements, and the Cu 3d band in Cu is not only wider than that in AgCu, but also asymmetric, which demonstrates that there is ac lear orbital interaction between the Cu atom and surrounding elements.…”

“…[7] Additionally,t here are other examples of efficient multinuclear WOCs for the first-row transition-metal (TM) complexes,s uch as some multinuclear cobalt polyoxometalates (POMs) [8] and tetranuclear copper complexes. Because mononuclear WOCs are easily prepared and the structure can be controllably synthesized, some mononuclear WOCs have been prepared recently,s uch as mononuclear manganese embedded in nitrogen-doped graphene (Mn-NG), [14] AgCu, [15] and Ni-PY5 (PY5:2 ,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine). [10] On multinuclear catalysts, the formation of the OÀOb ond is usually regarded as the rate-determining step during the OER.…”