Spinel oxides, e.g., NiCo₂O₄, is a promising catalyst for the catalytic oxidation of toluene. Understanding and designing versatile NiCo₂O₄ spinel is important for low-temperature toluene oxidation. Here, we investigated the surface-characteristic-dependent degradation activity of NiCo₂O₄ crystals through experiment and characterization. NiCo₂O₄ nanosheet using ethanol as solvent (named E--NiCo₂O₄) exposing {110} crystal planes exhibited the lowest temperature toluene oxidation. The T₉₉ of toluene conversion was 256 °C, which is much lower than that of NiCo₂O₄ nanosheet using ethylene glycol as solvent (named EG--NiCo₂O₄), NiCo₂O₄ octahedron (named O--NiCo₂O₄) and NiCo₂O₄ truncated octahedron (named TO--NiCo₂O₄). Characterization using various techniques such as XRD, TEM, BET, XPS, H₂-TPR and CO₂-TPD showed that Co³⁺ and surface adsorbed oxygen (O_sur) enriched surface, excellent redox properties and effective diffusion of the reaction product reasonably explain the enhancement in catalytic activity over the E--NiCo₂O₄. The research reveals that the effect of specific crystal planes and solvent was the key factor to govern the activity of low-temperature toluene oxidation.

尖晶石氧化物，例如NiCo ₂ O ₄，是用于甲苯催化氧化的有前途的催化剂。了解和设计多功能的NiCo ₂ O ₄尖晶石对于低温甲苯氧化非常重要。在这里，我们通过实验和表征研究了NiCo ₂ O ₄晶体的表面特性相关的降解活性。以乙醇为溶剂的NiCo ₂ O ₄纳米片（命名为E--NiCo ₂ O ₄）暴露了{110}晶面，表现出最低的甲苯氧化温度。T ₉₉甲苯的转化温度为256°C，远低于使用乙二醇作为溶剂（命名为EG--NiCo ₂ O ₄），NiCo ₂ O ₄八面体（命名为O--NiCo ₂ O ₄）的NiCo ₂ O ₄纳米片的转化率）和NiCo ₂ O ₄截短的八面体（命名为TO--NiCo ₂ O ₄）。使用XRD，TEM，BET，XPS，H ₂ -TPR和CO ₂ -TPD等各种技术进行的表征表明，Co ³⁺和表面吸附的氧（O _sur）富集的表面，出色的氧化还原特性和反应产物的有效扩散，可以合理地解释与E--NiCo ₂ O _4相比催化活性的增强。研究表明，特定的晶面和溶剂的影响是控制低温甲苯氧化活性的关键因素。