Evaluating the Catalytic Efficiency of Paired, Single-Atom Catalysts for the Oxygen Reduction Reaction
Evaluating the Catalytic Efficiency of Paired, Single-Atom Catalysts for the Oxygen Reduction Reaction
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DOI：
10.1021/acscatal.9b02178
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发表时间：
2019-09-01
期刊：
影响因子：
12.9
通讯作者：
Searles, Debra J.
中科院分区：
文献类型：
--
作者：
Hunter, Michelle A.;Fischer, Julia M. T. A.;Searles, Debra J.
配对的单原子催化剂在计算和实验中证明了协同效应，使它们在电化学反应中的性能优于基准催化剂铂/碳。我们通过筛选氮掺杂石墨烯中不同的过渡金属原子(M=Co，Pt，Fe，Ni)来考察它们催化氧还原反应(ORR)的能力，以探索这些催化剂的局限性。我们使用密度泛函理论方法来探索影响催化活性的电子因素，以努力使材料性能的趋势合理化，这些材料是下一代电催化剂的候选材料。结果表明，CoPT@N8V4是由掺氮的石墨烯(N8V4)中的四原子空位中的Co和Pt组成的，其过电势(ETA)为0.30V，其次是Co和Ni(ETA=0.35V)和成对的Co(ETA=0.37V)。活性的来源是活性Co原子通过观察金属配对对孔道的局部扭曲而改变了还原电势。我们利用ORR标度关系并在火山图上绘制催化活性，我们将其与ORR的OH中间体中的O原子的反键相互作用的程度相关联。我们确定，成对催化剂的局部调节允许金属原子的反应性被特定地修饰，以获得所需的反应性。
Paired, single-atom catalysts have been shown to demonstrate synergistic effects computationally and experimen tally which enable them to outperform the benchmark catalyst, Pt/C, for electrochemical reactions. We explore the limit of these catalysts by screening different transition metal atoms (M = Co, Pt, Fe, Ni) in nitrogen-doped graphene for their ability to catalyze the oxygen reduction reaction (ORR). We employ density functional theory methods to explore the electronic factors affecting catalytic activity in an effort to rationalize trends in the performance of materials which are promising candidates for the next generation of electrocatalysts. It is found that CoPt@N8V4, composed of paired Co and Pt in a nitrogen- doped four-atom vacancy in graphene (N8V4), performs ideally for the ORR with an overpotential (eta) of 0.30 V, followed closely by Co and Ni (eta = 0.35 V) and paired Co (eta = 0.37 V). The origin of activity is suggested to be the changing reduction potential of the active Co atom via the local distortion of the pore by the spectating metal partner. We utilize the ORR scaling relations and plot catalytic activity on a volcano plot, which we correlate with the degree of antibonding interactions with the O atom in the OH intermediate of the ORR. We establish that the local tuning of paired catalysts allows for the reactivity of metal atoms to be specifically modified for desirable reactivity.