The chemical stability of ZIF-8 nan

通过将合成后的样品悬浮在沸水和甲醇中，检查了ZIF-8纳米晶体的化学稳定性。通过XRD研究和SEM检查再次监测结构完整性。如图4所示，与合成样品相比，ZIF-8纳米晶体在沸水中至少稳定5天，因为XRD图案，样品的晶体形态甚至颜色都几乎没有变化（图6）。 4（b））。在沸腾甲醇的情况下，即使将浸泡时间延长至7天，其晶体结构和晶体形态也能很好地保留。我们纳米级ZIF-8晶体的化学稳定性与微米级产品报道的结果相当。<br>总而言之，我们首次报道了<br>纯水溶液中ZIF-8晶体的合成。这也是在纯水溶液中合成的ZIF材料的第一个示例。与在有机介质中开发的合成工艺相比，该合成方法使我们能够在更短的时间内制备ZIF-8纳米晶体，并提高了产品产量。彻底的稳定性研究表明，在去除客体分子以激活孔的过程中，多孔结构不会塌陷。该产品显示出优异的热稳定性和化学稳定性，并改善了水热稳定性。我们希望该方法在未来的研究中能够刺激更多的ZIF材料在水溶液中合成，从而开辟出更高效，更经济的方法来合成这些材料。

The chemical stability of ZIF-8 nanocrystals was examined by suspending the as-synthesized samples in boiling water and methanol. The structure integrity was again monitored by the XRD studies and the SEM inspections. As shown in Fig. 4, ZIF-8 nanocrystals are stable in boiling water for at least 5 days since the XRD pattern, the crystal morphology and even the color of the sample showed almost no change compared to the as-synthesized sample (Fig. 4(b)). In the case of boiling methanol, even the soaking period was prolonged to 7 days, the crystal structure as well as the crystal morphology was preserved very well. The chemical stability of our nanometresized ZIF-8 crystals is comparable to the results reported for the micrometre-scaled product.4 The excellent solvothermal stability shall increase the potential of ZIF-8 nanocrystals in applications in catalysis, adsorption and gas separation, because scaling down the crystal size from micrometre to nanometre scale will lead to enhanced physical properties such as increased surface area and decreased diffusion resistance.24,25<br> In summary, for the first time we reported the synthesis of<br>ZIF-8 crystals in pure aqueous solution. It is also the first example of ZIF materials synthesized in pure aqueous solutions. The synthesis method allowed us to make ZIF-8 nanocrystals in a much shorter time with improved product yield compared to the synthesis processes developed in organic media. Thorough stability studies indicated that the porous structure would not collapse during the removal of guest molecules to activate the pores. The product showed excellent thermal and chemical stabilities, and improved hydrothermal stability. We expect the method can stimulate more ZIF materials synthesized in aqueous solution in future studies and thus open up more efficient and economical ways to synthesize these materials.

将合成的样品悬浮于沸水和甲醇中，考察了ZIF-8纳米晶的化学稳定性。通过XRD分析和SEM观察，再次对其结构完整性进行了监测。如图4所示，ZIF-8纳米晶在沸水中至少稳定5天，因为XRD图谱、晶体形貌甚至样品颜色与合成样品相比几乎没有变化（图4（b））。在甲醇沸腾的情况下，即使浸泡时间延长到7d，晶体结构和晶体形貌也得到了很好的保存。我们纳米化的ZIF-8晶体的化学稳定性与报道的微米级产品的结果相当。4优异的溶剂热稳定性将增加ZIF-8纳米晶体在催化、吸附和气体分离方面的应用潜力，因为将晶体尺寸从微米缩小到纳米结垢将导致物理性能的提高，如表面积的增加和扩散阻力的降低。24,25<br>总之，我们第一次报道了<br>纯水溶液中的ZIF-8晶体。这也是在纯水溶液中合成ZIF材料的第一个例子。这种合成方法使我们能够在较短的时间内制备出ZIF-8纳米晶，并且与在有机介质中发展的合成方法相比，产品收率得到了提高。深入的稳定性研究表明，在去除客体分子以活化孔隙的过程中，多孔结构不会发生坍塌。该产品具有优异的热稳定性和化学稳定性，并改善了水热稳定性。我们希望该方法能在今后的研究中促进更多的水溶液中合成ZIF材料，从而开辟更有效、更经济的合成方法。<br>