Development of nanomaterials with multienzyme-like activities (nanozymes) via a simple way has attracted paramounting attention. Generally, enzymatic activity is closely related to the size, surface state, material type, etc. Bimetallic oxides are very appealing owing to their mixed valence and structural advantages. Herein, we reported an eco-friendly strategy to synthesize Co_1.5Mn_1.5O₄ nanozyme via sol-gel method. This nanozyme functionally mimics four major enzymes, i.e. laccase, peroxidase (POD), oxidase (OXD), and catalase (CAT). Accordingly, a colorimetric sensing platform was designed to distinguish isomers of organic pollutants ‒catechol (CC) and hydroquinone (HQ) by using Co_1.5Mn_1.5O₄ as the sole catalyst. In particular, laccase-like activity of Co_1.5Mn_1.5O₄ enables it to directly oxidize CC into yellow o-benzoquinone with good linearity in the range of 1∼1000 μM and a detection limit of 0.35 μM. Meanwhile, HQ can discolor the oxidized substrate that was pre-oxidized with the aid of oxidase-like activity of the nanozyme (linear range: 0.05∼100 μM, detection limit: 0.04 μM). The established colorimetric method has been successfully utilized for selective sensing of CC, HQ in water samples with good selectivity and high sensitivity. Our study contributes to green synthesis of metal-based nanomaterials with multi-enzyme mimicking activities and uncovers new usage of nanozyme in discriminating of environmental pollutants.

通过简单的方法开发具有多酶样活性（纳米酶）的纳米材料引起了人们的极大关注。通常，酶活性与尺寸，表面状态，材料类型等密切相关。双金属氧化物由于其混合价和结构优势而非常有吸引力。在本文中，我们报道了一种通过溶胶-凝胶法合成Co _1.5 Mn _1.5 O ₄纳米酶的环保策略。该纳米酶在功能上模拟四种主要酶，即漆酶，过氧化物酶（POD），氧化酶（OXD）和过氧化氢酶（CAT）。因此，设计了一种比色传感平台，通过使用Co _1.5 Mn _1.5 O ₄来区分有机污染物‒儿茶酚（CC）和对苯二酚（HQ）的异构体。作为唯一的催化剂。特别是，Co _1.5 Mn _1.5 O _4的漆酶样活性使其能够将CC直接氧化成黄色o-苯醌，线性度良好，在1至1000μM的范围内，检出限为0.35μM。同时，HQ借助纳米酶的类似氧化酶的活性（线性范围：0.05〜100μM，检测极限：0.04μM）可以使被预氧化的被氧化底物脱色。建立的比色法已被成功地用于选择性检测和高灵敏度的水样中CC，HQ的选择性检测。我们的研究有助于绿色合成具有多种酶模仿活性的金属基纳米材料，并揭示了纳米酶在区分环境污染物中的新用途。