Li Pei-Hua, Yang Meng, Li Yi-Xiang, Song Zong-Yin, Liu Jin-Huai, Lin Chu-Hong, Zeng Jie, Huang Xing-Jiu
Key Laboratory of Environmental Optics and Technology and Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, P. R. China.
Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Strongly-Coupled Quantum Matter Physics of Chinese Academy of Sciences, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, P. R. China.
Anal Chem. 2020 Apr 21;92(8):6128-6135. doi: 10.1021/acs.analchem.0c00677. Epub 2020 Apr 1.
Achieving highly sensitive and selective detection of trace-level As(III) and clarifying the underlying mechanism is still a intractable problem. The electroanalysis of As(III) relies on the electrocatalytic ability of the sensing interface. Herein, we first adopt single-atom catalysts as the electrocatalyst in As(III) detection. Cobalt single-atoms anchored on nitrogen-doped carbon material (Co SAC) were found to have an extraordinary sensitivity of 11.44 μA ppb with excellent stability and repeatability, which so far is the highest among non-noble metal nanomaterials. Co SAC also exhibited a superior selectivity toward As(III) compared with some bivalent heavy metal ions (HMIs). Combining X-ray absorption spectroscopy (XAFS), density functional theory (DFT) calculation, and reaction kinetics simulation, we demonstrated that Co single atoms stabilized in NC support serve as active sites to catalyze HAsO reduction via the formation of Co-O hybridization bond, leading to a lower energy barrier, promoting the breakage of As-O bonds. Importantly, the first electron transfer is the rate-limiting step of arsenic reduction and is found to be more favorable on Co-SAC both thermodynamically and kinetically. This work not only expands the potential applicaiton of single-atom catalysts in the detection and treatment of As(III), but also provides atomic-level catalytic insights into HMIs sensing interfaces.
实现对痕量 As(III) 的高灵敏度和高选择性检测并阐明其潜在机制仍然是一个棘手的问题。As(III) 的电分析依赖于传感界面的电催化能力。在此，我们首次采用单原子催化剂作为 As(III) 检测中的电催化剂。发现锚定在氮掺杂碳材料上的钴单原子（Co SAC）具有 11.44 μA ppb 的非凡灵敏度，具有出色的稳定性和可重复性，这是迄今为止非贵金属纳米材料中最高的。与一些二价重金属离子（HMI）相比，Co SAC 对 As(III) 也表现出优异的选择性。结合 X 射线吸收光谱（XAFS）、密度泛函理论（DFT）计算和反应动力学模拟，我们证明了稳定在 NC 载体中的 Co 单原子作为活性位点，通过形成 Co-O 杂化键催化 HAsO 还原，导致更低的能垒，促进 As-O 键的断裂。重要的是，第一次电子转移是砷还原的限速步骤，并且发现在 Co-SAC 上在热力学和动力学上都更有利。这项工作不仅扩展了单原子催化剂在 As(III) 检测和处理中的潜在应用，还为 HMI 传感界面提供了原子级的催化见解。
