Rock Salt Ni/Co Oxides with Unusual Nanoscale-Stabilized Composition as Water Splitting Electrocatalysts
Rock Salt Ni/Co Oxides with Unusual Nanoscale-Stabilized Composition as Water Splitting Electrocatalysts
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DOI：
10.1002/adfm.201605121
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发表时间：
2017-02-23
影响因子：
19
通讯作者：
Fattakhova-Rohlfing, Dina
中科院分区：
文献类型：
--
作者：
Fominykh, Ksenia;Tok, Guelen Ceren;Fattakhova-Rohlfing, Dina
纳米尺度对亚稳相形成的影响是纳米结构的一个重要方面，可以导致发现不寻常的材料成分。在这里，Ni/Co混合氧化物纳米晶的合成，结构表征，和在析氢反应（HER）和析氧反应（OER）的电化学性能的报告和纳米尺度上的组成和溶解度范围的影响进行了研究。采用叔丁醇溶剂热法合成了具有岩盐型结构的超细晶型、高分散性的NixCo 1-xO纳米粒子。混合氧化物的特点是在整个组合物范围内具有不寻常的可溶解性的非平衡相，这归因于纳米级结合颗粒形成的动力学控制的稳定作用。取代纳入钴和镍原子到岩盐晶格NiO氧化的形式电位，不断移动到较低的值，随着钴含量的增加有显着的效果。这可能与（001）和（111）-取向的表面的功函数的单调减少与Co含量的增加，从密度泛函理论（DFT+U）计算得到。此外，NixCo 1-xO纳米粒子在水裂解中的电催化性能也发生了显著的变化。OER活性随着Ni含量的增加而不断增加，而HER活性显示出相反的趋势，随着Co含量的增加而增加。非平衡NixCo 1-xO纳米粒子在HER和OER中的高电催化活性和可调性能在用于整体水裂解的电催化剂的设计中表现出巨大的潜力。
The influence of nanoscale on the formation of metastable phases is an important aspect of nanostructuring that can lead to the discovery of unusual material compositions. Here, the synthesis, structural characterization, and electrochemical performance of Ni/Co mixed oxide nanocrystals in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is reported and the influence of nanoscaling on their composition and solubility range is investigated. Using a solvothermal synthesis in tert-butanol ultrasmall crystalline and highly dispersible NixCo1-xO nanoparticles with rock salt type structure are obtained. The mixed oxides feature non-equilibrium phases with unusual miscibility in the whole composition range, which is attributed to a stabilizing effect of the nanoscale combined with kinetic control of particle formation. Substitutional incorporation of Co and Ni atoms into the rock salt lattice has a remarkable effect on the formal potentials of NiO oxidation that shift continuously to lower values with increasing Co content. This can be related to a monotonic reduction of the work function of (001) and (111)-oriented surfaces with an increase in Co content, as obtained from density functional theory (DFT+U) calculations. Furthermore, the electrocatalytic performance of the NixCo1-xO nanoparticles in water splitting changes significantly. OER activity continuously increases with increasing Ni contents, while HER activity shows an opposite trend, increasing for higher Co contents. The high electrocatalytic activity and tunable performance of the nonequilibrium NixCo1-xO nanoparticles in HER and OER demonstrate great potential in the design of electrocatalysts for overall water splitting.