Nanoscale Reactivity Mapping of a Single-Crystal Boron-Doped Diamond Particle
Nanoscale Reactivity Mapping of a Single-Crystal Boron-Doped Diamond Particle
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DOI：
10.1021/acs.analchem.1c00053
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发表时间：
2021-03-30
影响因子：
7.4
通讯作者：
Takahashi, Yasufumi
中科院分区：
文献类型：
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作者：
Ando, Tomohiro;Asai, Kai;Takahashi, Yasufumi
掺硼金刚石（BDD）通常通过化学气相沉积（CVD）以多晶形式生长，其中电化学响应在整个表面上平均。解卷积晶体取向、表面终止和掺硼浓度对电化学响应的影响是极具挑战性的。为了解决这一问题，我们使用CVD方法培养BDD的分离单晶微粒子，暴露晶面（100，方形）和（111，三角形），并结合跳模扫描电化学电池显微镜（HM-SECCM）对单个晶面（平面和非平面）进行电化学分析。用两种不同的氧化还原介质[Ru(NH3)(6)]（3+/2+）和Fe(CN)(6)（4-/3-）对氢（H-）和氧（O-）端单晶面进行了测量。从线性扫描和循环伏安实验中提取的所有测量点（像素点）的半波电位明确表明，由于硼掺杂的差异，电子在h端（111）表面的转移速度比h端（100）表面快。当比较o端（100）表面和h端（100）表面时，[Ru(NH3)(6)]（3+/2+）的差异最为显著。h表面电导率层的去除和与电位相关的态密度被认为是观察到的行为的原因。最后，在生长的h端多晶BDD电极上的电化学活性呈双峰分布，这归因于材料中不同掺杂的（100）和（111）面占主导地位。
Boron-doped diamond (BDD) is most often grown by chemical vapor deposition (CVD) in polycrystalline form, where the electrochemical response is averaged over the whole surface. Deconvoluting the impact of crystal orientation, surface termination, and boron-doped concentration on the electrochemical response is extremely challenging. To tackle this problem, we use CVD to grow isolated single-crystal microparticles of BDD with the crystal facets (100, square-shaped) and (111, triangle-shaped) exposed and combine with hopping mode scanning electrochemical cell microscopy (HM-SECCM) for electrochemical interrogation of the individual crystal faces (planar and nonplanar). Measurements are made on both hydrogen- (H-) and oxygen (O-)-terminated single-crystal facets with two different redox mediators, [Ru(NH3)(6)](3+/2+) and Fe(CN)(6)(4-/3-). Extraction of the half-wave potential from linear sweep and cyclic voltammetric experiments at all measurement (pixel) points shows unequivocally that electron transfer is faster at the H-terminated (111) surface than at the H-terminated (100) face, attributed to boron dopant differences. The most dramatic differences were seen for [Ru(NH3)(6)](3+/2+) when comparing the O-terminated (100) surface to the H-terminated (100) face. Removal of the H-surface conductivity layer and a potential-dependent density of states were thought to be responsible for the behavior observed. Finally, a bimodal distribution in the electrochemical activity on the as-grown H-terminated polycrystalline BDD electrode is attributed to the dominance of differently doped (100) and (111) facets in the material.