Probing Activities of Individual Catalytic Nanoflakes by Tunneling Mode of Scanning Electrochemical Microscopy
Probing Activities of Individual Catalytic Nanoflakes by Tunneling Mode of Scanning Electrochemical Microscopy
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DOI：
10.1021/acs.jpcc.1c07309
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发表时间：
2021-11
期刊：
影响因子：
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通讯作者：
Tianyu Bo;Xiang Wang;Rui Jia;Lili Han;Huolin L. Xin;Hanyu Zhang;E. Miller;M. Mirkin
中科院分区：
文献类型：
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作者：
Tianyu Bo;Xiang Wang;Rui Jia;Lili Han;Huolin L. Xin;Hanyu Zhang;E. Miller;M. Mirkin
隧道模式的扫描电化学显微镜（SECM）是最近发展起来的，并应用于研究单个金属纳米粒子（NPs）的电荷转移反应。当SECM尖端被带到离导电NP的隧穿距离内时，颗粒开始充当纳米电极的一部分。在这里，我们证明了使用具有非常薄的绝缘鞘层的碳纳米电极在平坦样品上进行电化学隧穿实验的可能性。以这种方式，层状纳米材料中的电催化活性、导电性和充电特性以及法拉第过程可以通过单纳米片伏安法来表征，而不与它们直接欧姆接触。隧道SECM实验的广泛适用性通过探测具有不同尺寸、几何形状和电催化性质的纳米材料来证明，包括金属/伪金属（1 T/1 T ′）和半导体（2 H）MoS 2纳米片、N掺杂多孔碳催化剂和MXene纳米片。将单个纳米片处的析氢反应（HER）和析氧反应（OER）的塔菲尔图与附着于宏观电极表面的薄片集合的类似测量进行比较。此外，我们观察到由非均匀掺杂引起的单个MXene薄片对HER和OER的催化活性的变化。
The tunneling mode of scanning electrochemical microscopy (SECM) was developed recently and applied to studies of charge-transfer reactions at single metal nanoparticles (NPs). When an SECM tip is brought within the tunneling distance from a conductive NP, the particle begins to act as a part of the nanoelectrode. Herein, we demonstrate the possibility of using carbon nanoelectrodes with a very thin insulating sheath for electrochemical tunneling experiments at flat samples. In this way, electrocatalytic activity, conductivity, and charging properties of and faradaic processes in layered nanomaterials can be characterized by single-nanoflake voltammetry without making direct ohmic contact with them. A broad applicability of tunneling SECM experiments is demonstrated by probing nanomaterials with different size, geometry, and electrocatalytic properties, including metallic/pseudo-metallic (1T/1T′) and semiconducting (2H) MoS2nanoflakes, N-doped porous carbon catalyst, and MXene nanosheets. The Tafel plots for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at individual nanoflakes are compared to analogous measurements for an ensemble of flakes attached to the surface of a macroscopic electrode. Moreover, we observed variations in catalytic activities of individual MXene flakes toward HER and OER caused by non-uniform doping.