Metal-organic frameworks (MOFs) have been used to detect uric acid (UA), but still very challenging to achieve a low detection limit due to the low inferior conductivity of MOFs. Herein, three different N-doped ZIF-67-derived carbons were synthesized for the first time by one-step co-pyrolysis of 2-methylimidazole with cobalt nitrate (CN), cobalt acetate (CA) or cobalt chloride (CC) toward UA sensing. Afterwards, the cobalt nitrate-derived Co particle (Co/CN) supported by N-doped ZIF-67-derived carbon displays extremely low detection limit and high sensitivity for UA, outperformed all reported MOFs-based UA sensors. More interestingly, it was discovered that the high valence Co within the Co/CN sample produced in high-acidic environment can intercalate in the frame for a bridge adsorption between two reaction sites, which boosted simultaneous 2-electron transfer, while Co only allows an end-adsorption structure for one-electron transfer being the rate determining step. Furthermore, the bridge adsorption mode of UA on Co -based catalyst was also verified by theoretical DFT calculations and XPS experiment. This work holds great promise for a selective and sensitive UA sensor for practical bioscience and clinic diagnostic applications while shedding lights in fundamental research for innovative designs and developments of high-sensitive electrochemical sensors.

中文翻译：

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多孔 ZIF-67 中的 Co4+ 衍生出 2 个反应位点的插层桥吸附，用于同时进行 2 个电子转移，从而实现尿酸的灵敏检测


金属有机框架（MOF）已被用于检测尿酸（UA），但由于MOF的电导率较低，要实现较低的检测限仍然非常具有挑战性。在此，通过2-甲基咪唑与硝酸钴（CN）、乙酸钴（CA）或氯化钴（CC）一步共热解制备UA，首次合成了三种不同的N掺杂ZIF-67衍生碳。传感。随后，由 N 掺杂 ZIF-67 衍生碳支撑的硝酸钴衍生 Co 颗粒 (Co/CN) 对 UA 显示出极低的检测限和高灵敏度，优于所有报道的基于 MOF 的 UA 传感器。更有趣的是，我们发现在高酸性环境中产生的Co/CN样品中的高价Co可以插入框架中，在两个反应位点之间形成桥吸附，从而促进同时2电子转移，而Co只允许单电子转移的末端吸附结构是速率决定步骤。此外，通过理论DFT计算和XPS实验也验证了UA在Co基催化剂上的桥吸附模式。这项工作为实际生物科学和临床诊断应用的选择性和灵敏的UA传感器带来了巨大的希望，同时为高灵敏度电化学传感器的创新设计和开发的基础研究提供了线索。