Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China.
Acc Chem Res. 2023 Feb 7;56(3):374-384. doi: 10.1021/acs.accounts.2c00777. Epub 2023 Jan 27.
ConspectusPorous materials have wide applications in the fields of catalysis, separation, and energy conversion and storage. Porous materials contain pores that are specifically designed to achieve expectant performance. The solid phases in porous materials are normally completely continuous to form the basic porous frame while the pores are fluid phase within the solid phase. Single crystals are macroscopic materials in three spatial dimensions with the constituent atoms, ions, molecules, or molecular assemblies arranged in an orderly repeating pattern with the ordered structures. The growth of single crystals is indeed a process to arrange these constituents in three dimensions into a repeating pattern within the materials. Today the applications of single crystals are exponentially growing in wide fields, and single crystals are therefore unacknowledged as the pillars of our modern technology. Introducing porosity into single crystals would be expected to create a new kind of porous material in which the basic porous frames are single-crystalline and free of grain boundaries. The structural symmetry is completely maintained within the basic porous frames which are a continuous solid phase, but it is completely lost inside the pores. The porous architecture is free of grain boundaries, and the fully interconnected skeletons are in single-crystalline states within the basic porous frames. Single crystals with porosities can therefore be considered to be a new kind of porous material, but they are single-crystal-like because the structural symmetry is maintained only in the skeletons and completely lost within the pores. We therefore call them porous single crystals or consider them in porous single-crystalline states to stand out with their structural features. Porous single crystals at the macroscale combine the advantages of porous materials and single crystals to incorporate both porosity and structural coherence in a porous architecture, leading to invaluable opportunities to alter the material's properties by controlling the unique structural features to enhance its performance. However, the growth of single crystals in three dimensions reduces the formation of porosities, leading to a fundamental challenge for introducing porosity into single crystals in a traditional process of crystal growth. In this Account, we report the rational design, growth methodology, and microstructural engineering of porous single crystals in a solid-solid transformation. We rationally design a high-density mother phase in a single-crystalline state and transform it into a low-density new phase in a single-crystalline state to introduce porosities into single crystals even incorporating the removal of specific compositions from the mother phase during the growth of porous single crystals. The porosity can be tailored by controlling the change in relative densities from the mother phase to the porous single crystals while the pore size can be engineered by controlling the fabrication conditions. Considering the unique structural features, we explore their functionalities and applications in photoelectrochemical energy conversion, electrochemical alkane conversion, and electrochemical energy storage. We believe that the materials, if tailored into porous single-crystalline states, would not only find a broad range of applications in other fields but also enable a new path for material innovations.
概述多孔材料在催化、分离和能量转换与存储等领域有着广泛的应用。多孔材料包含专门设计的孔，以实现预期的性能。多孔材料的固相通常是完全连续的，形成基本的多孔骨架，而孔是固相中的流体相。单晶是具有三个空间维度的宏观材料，其组成原子、离子、分子或分子组装以有序重复的模式排列，具有有序的结构。单晶的生长实际上是一个将这些组成部分在三维空间中排列成材料内部重复图案的过程。如今，单晶的应用在广泛的领域中呈指数级增长，因此单晶被认为是现代技术的支柱。在单晶中引入多孔性有望创造出一种新的多孔材料，其中基本的多孔骨架是单晶的，没有晶界。在基本多孔骨架中，结构对称性完全保持，但在孔内完全丢失。多孔结构没有晶界，完全互连的骨架在基本多孔骨架中处于单晶状态。具有多孔性的单晶因此可以被认为是一种新的多孔材料，但它们是单晶状的，因为只有骨架保持结构对称性，而在孔内完全丢失。因此，我们称它们为多孔单晶或在多孔单晶态下考虑它们，以突出其结构特征。宏观尺度上的多孔单晶结合了多孔材料和单晶的优势，在多孔结构中结合了多孔性和结构连贯性，为通过控制独特的结构特征来改变材料的性质提供了宝贵的机会，从而提高其性能。然而，单晶在三维空间中的生长减少了孔隙的形成，导致在传统的单晶生长过程中向单晶中引入孔隙这一基本挑战。在本报告中，我们报告了在固-固转变中多孔单晶的合理设计、生长方法和微观结构工程。我们合理地设计了高密度的母体相，并将其转化为低密度的新相，即使在多孔单晶的生长过程中从母体相中去除特定的成分，也能将多孔性引入单晶。通过控制从母体相到多孔单晶的相对密度的变化，可以对孔隙率进行调整，而通过控制制造条件可以对孔径进行设计。考虑到独特的结构特征，我们探索了它们在光电化学能量转换、电化学烷烃转化和电化学储能中的功能和应用。我们相信，如果将这些材料设计成多孔单晶态，它们不仅会在其他领域得到广泛应用，而且还会为材料创新开辟一条新的道路。
