The rational design of nitrite sensors has attracted significant research interest due to their widespread use and the associated risks of methemoglobinemia and carcinogenicity. The undisclosed nitrite-sensing performance of the spinel cobaltite MnCo₂O₄ (MCO) prepared by an oxalate-assisted coprecipitation method is reported in this study. Spectroscopy and microscopy investigations revealed the formation of uniform MCO nanorods with a high aspect ratio. The electrocatalytic nitrite oxidation at the MCO-coated glassy carbon electrode (MCO/GCE) indicated the promising performance of the synthesized material for nitrite sensing. MCO/GCE detects nitrite in a concentration range of 5 μM to 3 mM and has a limit of detection of 0.95 μM with a higher sensitivity of 857 μA mM^–1 cm^–2 in a response time of 4 s. In MCO, the mixed-valence states of Co²⁺/Co³⁺ confer a high electrical conductivity, and higher valent redox couples of Mn and Co impart remarkable electrocatalytic activity toward nitrite oxidation. MCO spinel undergoes facile and ultrafast faradaic reactions to mediate nitrite oxidation. Additionally, the mesopores of MCO nanorods facilitate the rapid diffusion of electrolyte and nitrite ions. Employing the electrode in sensing nitrite in milk, lake, and tap water samples further validates its potential application in real-life testing. MCO spinel nanorods showcase promising scope for utilization in the electrochemical sensing of nitrite and inspire further exploration of transition-metal oxide-based mixed-spinel materials.

中文翻译：

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用于高灵敏电化学检测亚硝酸盐的 MnCo2O4 尖晶石纳米棒


亚硝酸盐传感器的合理设计由于其广泛使用以及高铁血红蛋白血症和致癌性的相关风险而引起了人们的广泛研究兴趣。本研究报告了通过草酸盐辅助共沉淀法制备的尖晶石钴矿 MnCo ₂ O ₄ (MCO) 的未公开的亚硝酸盐传感性能。光谱学和显微镜研究揭示了具有高纵横比的均匀 MCO 纳米棒的形成。 MCO 涂层玻碳电极 (MCO/GCE) 上的电催化亚硝酸盐氧化表明合成材料在亚硝酸盐传感方面具有良好的性能。 MCO/GCE 可检测浓度范围为 5 μM 至 3 mM 的亚硝酸盐，检测限为 0.95 μM，响应灵敏度高达 857 μA mM ^–1 cm ^–2 时间4秒。在MCO中，Co ²⁺ /Co ³⁺ 的混合价态赋予了高电导率，而Mn和Co的高价氧化还原对赋予了亚硝酸盐氧化显着的电催化活性。 MCO 尖晶石经历轻松且超快的法拉第反应来介导亚硝酸盐氧化。此外，MCO纳米棒的介孔有利于电解质和亚硝酸根离子的快速扩散。使用该电极检测牛奶、湖水和自来水样品中的亚硝酸盐进一步验证了其在实际测试中的潜在应用。 MCO尖晶石纳米棒展示了在亚硝酸盐电化学传感中的广阔应用前景，并激发了对基于过渡金属氧化物的混合尖晶石材料的进一步探索。