Electronically Modified Atomic Sites Within a Multicomponent Co/Cu Composite for Efficient Oxygen Electroreduction

Abstract

Moreover, the stability issues of Pt-based catalysts (e.g., the crystallite dissolution and nanoparticle agglomeration) have also jeopardized the reliability of power systems including ORR as a half reaction. [7,8] In these regards, there is a general call for the replacement of the Pt-based composites with cost-effective, durable and highly active ORR catalysts.During the past few years, nitrogencoordinated transition metal species (TM-N x ) that are embedded within a carbon matrix have emerged as a class of promising catalysts for ORR, owing to their high activity, maximum utilization of the metal species and distinct configurations of active sites. Among them, the Fe-N-C catalysts demonstrate an exceptional ORR catalytic activity that is even comparable to the Pt/C benchmark. [9,10] Nevertheless, the usual insufficient durability of the Fe-N x species under long-term ORR operation has severely impeded their potential for commercial perspectives. [11] Although the actual degradation mechanism of Fe-N x centers is still under debate, it is clear that the reactive oxygen species (ROS) generated during the "electro-Fenton" process in the presence of Fe species and hydrogen peroxide tend to cause corrosion or oxidation of carbon that leads to the cleavage of Fe-N bond and the eventual decay of activity. [12,13] By contrast, CoN x -containing materials would have less deleterious effects in this regard and appear to be promising alternatives to the Fe-N-C catalysts in various applications, [14] as reported recently. [15,16] Nonetheless, despite significant progress in preparation methods, [17,18] it is still extremely challenging for CoN x -containing catalysts to be applied in large scale due to i) their insufficient activity compared with the Pt-based catalysts; [14,19] and ii) the relatively high percentage of H 2 O 2 produced during ORR that results in a lower energy efficiency and possible catalyst corrosion. [4,20,21,22] Thus, it is necessary to develop a strategy to enhance the catalytic ORR performance of the Co-N-based composites meanwhile suppress the H 2 O 2 production on them. [23] Herein, Cu species are introduced to mitigate the activity and high H 2 O 2 selectivity issues of Co-N based composites. For the first time, the different roles of CuN x and CoN x moieties in ORR have been investigated within a multicomponent Co/ Cu catalyst, both experimentally and theoretically. Atomically dispersed CuN x sites are proposed to be effective in reducing Rational design of cost-effective and active electrocatalysts is an essential step toward the large-scale realization of hydrogen fuel cells and metal-air batteries. Its success requires a drastic improvement in the kinetics of the cathodic oxygen reduction reaction (ORR). Herein, a novel ORR catalyst formed by encapsulating thin Cu layer decorated Co nanoparticles inside graphitic carbon layers that are embedded with abundant CoN x and CuN x atomic sites (denoted as SA-CoCu@Cu/CoNP), is reported. The multicomponent SA-CoCu@Cu/CoNP composite exhibits a r...

Confinement Effects in Individual Carbon Encapsulated Nonprecious Metal‐Based Electrocatalysts

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Electronically and Geometrically Modified Single‐Atom Fe Sites by Adjacent Fe Nanoparticles for Enhanced Oxygen Reduction

“…[8] Zhang et al reported an atomically dispersed Co and Cu dual metaldoped carbon material with Cu-decorated Co NPs encapsulated inside, exhibiting a remarkable ORR catalytic performance. [9] The co-existed NPs and TM-N x species significantly regulated the electronic structure of Co-N x active sites, which optimized…”

Vacuum vapor migration strategy for atom–nanoparticle composite catalysts boosting bifunctional oxygen catalysis and rechargeable Zn–air batteries

“…The significant geometrical, electronic, and synergistic effects between the different components in the alloys contribute to the enhancement of the intrinsic catalytic activity relative to that of single metal counterparts. 46 In addition to CoNi particles, some “alloy-free” area can be distinguished by the emergence of Co signals but lack of Ni signals, which indicates the presence of Co–N x –C sites. In Fig.…”