Abstract The controlled introduction of oxygen vacancies (OVs) in photocatalysts has been demonstrated to be an efficient approach for improving the separation of photogenerated charge carriers, and thus, for enhancing the photocatalytic performance of photocatalysts. In this study, a two-step calcination method where ZIF-8 was used as the precursor was explored for the synthesis of ZIF-8-derived ZnO nanoparticles with gradient distribution of OVs. Electron paramagnetic resonance measurements indicated that the concentration of OVs in the samples depended on the temperature treatment process. Ultraviolet–visible spectra supported that the two-step calcined samples presented excellent light-harvesting ability in the ultraviolet-to-visible light range. Moreover, it was determined that the two-step calcined samples presented superior photocatalytic performance for the removal of NO, and inhibited the generation of NO2. These properties could be attributed to the contribution of the OVs present in the two-step calcined samples to their photocatalytic performance. The electrons confined by the OVs could be transferred to O2 to generate superoxide radicals, which could oxidize NO to the final product, nitrate. In particular, the NO removal efficiency of Z 350-400 (which was a sample first calcined at 350 dC for 2 h, then at 400 dC for 1 h) was 1.5 and 4.6 times higher than that of Z 400 (which was one-step directly calcined at 400 dC) and commercial ZnO, respectively. These findings suggested that OV-containing metal oxides that derived from metal-organic framework materials hold great promise as highly efficient photocatalysts for the removal of NO.

中文翻译：

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具有可控氧空位量的 ZIF-8 衍生的 ZnO 纳米颗粒增强光催化 NO 去除和有毒 NO2 产生抑制

摘要 在光催化剂中受控引入氧空位 (OVs) 已被证明是改善光生载流子分离的有效方法，从而提高光催化剂的光催化性能。在这项研究中，探索了一种以 ZIF-8 为前驱体的两步煅烧方法，用于合成具有 OV 梯度分布的 ZIF-8 衍生的 ZnO 纳米颗粒。电子顺磁共振测量表明样品中 OV 的浓度取决于温度处理过程。紫外-可见光谱支持两步煅烧样品在紫外-可见光范围内表现出优异的光捕获能力。而且，确定两步煅烧样品具有优异的光催化去除 NO 的性能，并抑制了 NO2 的产生。这些特性可归因于两步煅烧样品中存在的 OV 对其光催化性能的贡献。OV 限制的电子可以转移到 O2 中以产生超氧自由基，这可以将 NO 氧化成最终产物硝酸盐。特别是，Z 350-400（即先在 350 dC 下煅烧 2 小时，然后在 400 dC 下煅烧 1 小时的样品）的 NO 去除效率是 Z 400（其为 1 倍）的 1.5 倍和 4.6 倍。直接在 400 dC 下煅烧）和商业氧化锌，分别。