In this study, we report that layered double hydroxides (LDH) exhibited high photocatalytic activities in degrading NOx gases for the first time. ZnAl-CO₃ LDHs with a 1.5 to 3.0 Zn/Al ratio were prepared by a coprecipitation method both with and without hydrothermal treatment. Syntheses were carried out with high and low metal concentrations, the latter being the most favorable in obtaining pure LDHs in the whole Zn/Al ratio range. The samples were characterized by different techniques such as PXRD, FT-IR, ICP mass, TGA, SBET, SEM and Diffuse reflectance (DR). The LDH particles grew as well-defined hexagonal nanolayers, whose size and crystallization depended on the synthetic procedure and the Zn/Al ratio. Those samples with lower crystallinity exhibit the highest specific surface area values (> 50 m²·g^-1). The ZnAl-CO₃ LDHs were UV light responsive with band–gap values close to 3.5 eV. The LDH photocatalysts show a high performance towards the photochemical oxidation process of NO gas, with efficiencies of around 55%. Remarkably, the ZnAl-CO₃ photocatalysts exhibit an impressive selectivity towards the deNOx process, avoiding the emission of the toxic NO₂ gas into the atmosphere. Interestingly, these promising deNOx results are repeated when working for a long irradiation period or with the highest concentration of NO in polluted atmospheres.

在这项研究中，我们报道了层状双氢氧化物（LDH）首次在降解NOx气体中表现出高的光催化活性。Zn / Al比为1.5到3.0的ZnAl-CO ₃ LDHs可以通过共沉淀法进行加水热处理和不加水热处理。在高和低金属浓度下进行合成，后者在获得整个Zn / Al比范围内的纯LDH方面最有利。通过不同的技术对样品进行表征，例如PXRD，FT-IR，ICP质量，TGA，SBET，SEM和漫反射率（DR）。LDH颗粒生长为轮廓分明的六边形纳米层，其大小和结晶度取决于合成程序和Zn / Al比。那些结晶度较低的样品表现出最高的比表面积值（> 50 m² ·g ^-1）。ZnAl-CO ₃ LDH具有紫外光响应，带隙值接近3.5 eV。LDH光催化剂对NO气体的光化学氧化过程显示出高性能，效率约为55％。值得注意的是，ZnAl-CO ₃光催化剂对脱硝工艺表现出令人印象深刻的选择性，避免了有毒NO ₂气体向大气中的排放。有趣的是，当长时间工作或在污染大气中的NO浓度最高时，这些有希望的deNOx结果会重复出现。