Abstract

Catalytic oxidation of formaldehyde (HCHO) at ambient temperature is an effective method for indoor HCHO removal. In this study, Ni/Co-Layered double hydroxides (LDHs) with different molar ratios were successfully synthesized via a one-step hydrothermal method. Their structure and morphology were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET)-specific surface area, X-ray photoelectron spectroscopy (XPS), and H₂ temperature-programmed reduction (H₂-TPR), respectively. The catalytic activity results show that Ni/Co-LDHs with the Ni/Co ratio of 1:2 exhibited enhanced activity for HCHO decomposition. The removal efficiency of indoor HCHO was up to 99.7% at ambient temperature, and it remained highly stable without any obvious deactivation even after a reaction time of 800 min. The abundant hydroxyl groups were favorable for catalytic activity, which could not only enrich the adsorption of HCHO on the surface of catalysts, but also directly react with HCHO to obtain CO₂ and H₂O. Moreover, the redox cycles of Ni³⁺/Ni²⁺ and Co³⁺/Co²⁺ would provide more reactive oxygen species and therefore promote catalytic reaction. This work can provide a new insight into LDH-based catalysts for low-concentration HCHO removal in practical application.

中文翻译：

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Ni / Co-LDHs分层催化剂在环境温度下催化氧化室内甲醛

摘要

在室温下催化氧化甲醛（HCHO）是去除室内HCHO的有效方法。在这项研究中，通过一步水热法成功地合成了不同摩尔比的Ni / Co层状双氢氧化物（LDHs）。通过X射线衍射（XRD），傅立叶变换红外光谱（FTIR），扫描电子显微镜（SEM），透射电子显微镜（TEM），Brunauer-Emmett-Teller（BET）比表面积表征了它们的结构和形态， X射线光电子能谱（XPS）和H _2程序升温还原（H ₂-TPR）。催化活性结果表明，Ni / Co-LDHs的Ni / Co比为1：2时，对HCHO的分解活性增强。室内HCHO在环境温度下的去除率高达99.7％，即使在800分钟的反应时间后仍保持高度稳定，没有任何明显的失活。丰富的羟基基团是催化活性，这可能不仅丰富HCHO的吸附催化剂的表面上有利，也可直接与HCHO反应，得到CO ₂和H ₂ O.此外，Ni的氧化还原循环³⁺ / Ni ²⁺和Co ³⁺ / Co ²⁺会提供更多的活性氧，从而促进催化反应。这项工作可以为基于LDH的催化剂在实际应用中去除低浓度HCHO提供新的见解。