MOF on MOF composites illustrated superb functional scalability, but few MOF on MOF composites had been applied in the direction of photocatalytic degradation. In this work, a series of P21-X (X = 1, 2, 3, 4) composites were synthesized and optimized with PCN-134 as the MOF seed and PCN-222 as the secondary MOF by an epitaxial growth method and applied to the photocatalytic degradation of nizatidine (NZT). P21-X had excellent substantial adsorption and photocatalytic properties. P21-3 exhibited the highest removal of 90.81% for NZT. The mechanism of P21-3 producing ¹O₂ was probed. Based on the results of UPLC-HRMS, the NDMA was not produced during the degradation process and rational pathways for degradation of NZT were proposed. The environmental toxicity of NZT degradation products was evaluated using ECOSAR, T.E.S.T. software and Vibrio fischeri luminescence inhibition, the results showed that the toxicity of the reaction solution was diminished after 120 min of photodegradation by P21-3. Moreover, given the strong anti-interference performance of ¹O₂, the photocatalytic degradation system constructed with P21-3 could be free from the interference of common anions, cations and dissolved organic matters. As a result, the photocatalytic activity of the system remained high removal of NZT in tap water, river water and seawater. The results demonstrated that the MOF on MOF composites P21-3, synthesized by the epitaxial growth method, had enhanced photodegradation capability. The current study not only avoids the generation of toxic by-products in the photocatalytic degradation process but also broadens the application area of MOF on MOF composites.

MOF 复合材料上的 MOF 显示出极好的功能可扩展性，但 MOF 复合材料上的 MOF 很少应用于光催化降解方向。本工作以 PCN-134 为 MOF 种子，PCN-222 为次级 MOF，采用外延生长法合成并优化了一系列 P21-X (X = 1, 2, 3, 4) 复合材料，并将其应用于尼扎替丁 (NZT) 的光催化降解。P21-X具有优异的显着吸附和光催化性能。P21-3 对 NZT 的去除率最高，为 90.81%。^P21-3产生1 O ₂的机理被探查。基于UPLC-HRMS的结果，在降解过程中没有产生NDMA，并提出了NZT降解的合理途径。利用ECOSAR、TEST软件和费氏弧菌发光抑制评价了NZT降解产物的环境毒性，结果表明，P21-3光降解120 min后反应液的毒性减弱。^{此外，鉴于1} O ₂的强抗干扰性能，用P21-3构建的光催化降解体系可以不受常见阴离子、阳离子和溶解有机物的干扰。结果，该系统的光催化活性在自来水、河水和海水中保持了较高的 NZT 去除率。结果表明，通过外延生长法合成的 MOF 复合材料 P21-3 上的 MOF 具有增强的光降解能力。目前的研究不仅避免了光催化降解过程中有毒副产物的产生，而且拓宽了MOF在MOF复合材料上的应用领域。