Synergetic Transformation of Solid Inorganic-Organic Hybrids into Advanced Nanomaterials for Catalytic Water Splitting.

Abstract

The rational synthesis of advanced nanomaterials with well-defined structures has been intensively studied due to the remarkable properties and intriguing applications of the formed materials. Recently, inorganic-organic hybrids have been widely adopted as precursors for chemical transformations toward the preparation of diverse nanomaterials. Specifically, inorganic and organic species with nano/molecule/atom-scale distribution serve as self-templates and sacrificial agents, respectively, endowing the products with controlled morphologies, band gaps, defects, and spatial architectures. However, previous works have focused mostly on the transformation of porous coordination polymers, such as metal-organic frameworks (MOFs), which would produce daughter nanomaterials with the inherited structure of their parental hybrids. Moreover, conventional transformation strategies often encounter difficulties in simultaneously manipulating multiple structural parameters of the target materials. Therefore, a synergetic transformation strategy involving the simultaneous removal of organic components and the reconstruction of inorganic components to transform solid inorganic-organic hybrids into functional nanomaterials is developed. In this Account, we review recent advances in the utilization of solid inorganic-organic hybrids as precursors and their transformation into inorganic functional nanomaterials through a synergetic transformation strategy with an emphasis on understanding the conversion mechanism. The synergetic transformation strategy we discussed is categorized by organic component removal coupled with different methods for the reconstruction of inorganic components, including ion exchange, interfacial reaction, redox reaction and self-assembly. The key to a synergetic transformation strategy lies in the cooperation and/or competition among different transformation tools through dynamics and/or thermodynamics. By controlling the rate and position of the ion exchange reaction coupled with the removal of organics, a series of nanomaterials with designed band gaps and spatial architectures are produced from the solid inorganic-organic hybrid nanosheet-based precursors. The dissimilarity of organics removal between the inner and outer regions of hybrids induced by interfacial reaction is capable of producing controlled porous/hollow structures. For the coupling of a redox reaction with organics removal, the products of the decomposition of organics induce the in situ oxidation/reduction of inorganic components to generate defects and a porous structure. Along with organics removal, the self-assembly of inorganic components can be achieved to yield novel nanomaterials with hierarchical structures. Based on the understanding of the conversion mechanism, diverse advanced nanomaterials with elaborately designed structures are prepared by adopting appropriate precursors and synergetic transformation strategies. We then summarize the applications of the conversion products for photo(electro)/electrocatalytic water splitting. The precisely modulated structure can specifically improve photon adsorption, electron transport, catalytic activity and durability. Thus, the conversion products can be directly used as photo(electro)/electrocatalysts with high activities and cycling stabilities. Finally, we provide an outlook on the current challenges and promising opportunities in this research area. We believe that the advanced synergetic transformation strategy of solid inorganic-organic hybrids will open up a new avenue for the preparation of nanomaterials with fascinating performance.