随着物联网技术的发展，便携、低成本快速检测环境中小分子化合物的方法正在兴起。作为一种快响应、低功耗的分析技术，电化学传感器可以用于水、气等各种环境介质。但其在实际应用中暴露出的数据可靠性低、选择性差、灵敏度低等问题限制了进一步发展。因而决定电化学传感器性能的敏感元件——电极材料需要被进一步优化。金属-氮掺杂碳催化剂作为一种有望替代贵金属的传感器电极材料，具有易制备、抗中毒、稳定性好等优点，但是其导电性差、活性不足导致难以被广泛利用。因此，亟待开发出高活性、高导电性的功能化金属-氮掺杂碳纳米电催化剂。论文通过理论和实验验证了金属-氮掺杂碳催化剂具有高稳定性和抗中毒性的原因。催化剂中氮元素的存在能够有效修饰局部电子结构、形成稳定的原子级金属或金属-氮位点、催化中间产物，从而提高催化剂的稳定性和抗干扰性能。发现了金属-氮掺杂碳催化剂在制备过程中孔道和缺陷位点随着碳化温度的变化规律，并针对催化环境小分子反应所需要的催化剂特性，提出了丰富金属活性位点、提高氮含量、提高导电性的功能化策略，进而制备了一系列具有丰富金属活性位点、高氮含量和高导电性的金属-氮掺杂碳催化剂，包括铂-氮掺杂碳和钴-氮掺杂碳纳米管。以铂-氮掺杂碳为例研究了对甲醛气体的检测。发现铂-氮掺杂碳对甲醛具有检测限低（0.04 mmol·L-1）、线性范围宽（0~45 mmol·L-1）、灵敏度高（12.22 μA·L·mmol-1·cm-2）、选择性强的优点。进而开发并评测了基于上述功能化催化剂的甲醛电化学传感器器件，在0~10 mg·L-1甲醛浓度区间内显示了良好的线性，检测限为0.2 mg·L-1，灵敏度为40 mV·L·mg-1。以钴-氮掺杂碳纳米管为例研究了对其他环境小分子过氧化氢的检测，发现钴-氮掺杂碳纳米管对过氧化氢具有检测限低（32.4 nmol·L-1）、线性范围宽（50 nmol·L-1~50 mmol·L-1）、灵敏度高（568.47 μA·L·mmol-1·cm-2）、重复性好（RSD=1.91%）的优点。与传统的分光光度法测试结果有可比性，且响应速度更快（40 s）、所需溶液更少（50 μL）。
The rapid detection of small compounds in the environment by means of portable and low-cost methods is emerging with the advancements in Internet of Things technology. As a fast response, low-power electrochemical analysis technology, electrochemical sensors can be used in various water and gas environments. However, the problems of high cost, poor data reliability, poor selectivity and low sensitivity in practical application limit their development. Therefore, the electrode materials, which determine the performance of electrochemical sensors, need to be further optimized to improve the sensitivity to the target analytes. Metal, nitrogen co-doped carbon catalyst, as a kind of potential electrode material of sensor to replace precious metals, has the advantages of easy preparation, wide source and good stability, but its poor conductivity and activity make it difficult to directly replace precious metals. Therefore, it is urgent to develop functional metal, nitrogen co-doped carbon nanocatalysts with high activity and conductivity. The mechanism of high stability and moderate toxicity of metal, nitrogen co-doped carbon catalyst was verified by theory and experiment. The presence of nitrogen in the catalyst can effectively modify the local electronic structure, form stable atom level metal or metal-nitrogen sites and catalyze the intermediates, so as to improve the stability and anti-interference performance of the catalyst. The mechanism of pore and defect sites of the metal, nitrogen co-doped carbon catalyst with the carbonization temperature during the preparation process was found. According to the characteristics of the catalyst needed for the small molecule reaction in the environment, the functional strategies of enriching the metal active sites, increasing the nitrogen content and improving the conductivity were proposed, and a series of metal, nitrogen co-doped carbon catalyst with rich metal activity, high nitrogen content and high conductivity were controllably synthesized.For instance, functional platinum-nitrogen doped carbon catalyst has the advantages of low detection limit (0.04 mmol·L-1), high sensitivity (12.22 μA·L·mmol-1·cm-2) and wide linear range (0~45 mmol·L-1) for formaldehyde sensing. The formaldehyde electrochemical sensor device based on the functional catalyst was further developed and evaluated, which also showed good linearity between 0~100 mg·L-1. The detection limit is 0.2 mg·L-1 and the sensitivity is 40 mV·L·mg-1.Similarly, the electrochemical sensor is also suitable for other small environmental molecules like hydrogen peroxide. Functional cobalt-nitrogen doped carbon nanotubes have the advantages of low detection limit (32.4 nmol·L-1), wide linear range (50 nmol·L-1 ~ 50 mmol·L-1), high sensitivity (568.47 μA·L·mmol-1·cm-2), and good repeatability (RSD=1.91%) for hydrogen peroxide sensing. Compared with the traditional spectrophotometry, the results are comparable, and the response speed is faster (40 s) and the required solution is less (50 μL).
