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The most employed strategies for adjusting the electrocatalytic activity and selectivity of covalent organic frameworks (COFs) in the oxygen reduction reaction involve modifying the number and placement of heteroatoms, degree of asymmetry, and molecular configuration of the building units. However, the utilization of linkage conversion, which can induce huge local structure change, has been rarely explored for achieving such goals. In this work, we present the successful conversion of imine linkages into nonsubstituted quinoline within thiazolo-[5,4-d]thiazole-based COFs via a Rh-catalyzed C–H activation strategy. This conversion resulted in improved performance in the oxygen reduction reaction, specifically the production of hydrogen peroxide with a selectivity of 61–69% in acid solution (pH = 3.1), a high production rate (106.3 mg L−1 in 100 min), and good durability. Control experiments and theoretical calculations were conducted to investigate the underlying mechanisms, indicating that the active sites could be the quinoline nitrogen and thiazole nitrogen. Furthermore, an analysis of the electronic structure revealed that the enhanced performance following linkage conversion was attributed to an increase in in-plane π electron delocalization. This delocalization induced charge redistribution around the active sites, optimizing the adsorption of oxygen intermediates. Overall, the work paves novel pathways to fine-tune the oxygen reduction reaction performance of COFs linked by imine bonds. [ABSTRACT FROM AUTHOR]

Metal halide perovskites are demonstrated to show fascinating optical and electronic properties, including highly efficient luminescence, outstanding carrier transport behavior, and large light absorption coefficient. In particular, halide perovskite single crystals are characterized with superior optoelectronic performance and enhanced stability, emerging as competitive candidates for applications in solar cells, light‐emitting diodes, lasers, photodetectors, and high‐energy radiation detectors. Recently, remarkable advances have been achieved to grow perovskite single crystals, while there are also many challenges in the control of growth defects and further improvement of the crystal quality. Concerning these factors, recent progress of metal halide perovskite crystals from the view of crystal growth is systematically summarized. Moreover, some ongoing challenges and perspectives for halide perovskite crystals are also proposed, which will possibly provide deeper insight into the exploration of novel perovskite crystals and related devices. [ABSTRACT FROM AUTHOR]

The effective parameters of the composite materials with Gurtin–Murdoch ((G-M) interfaces are analyzed by standard boundary element method (BEM)-based equivalent inhomogeneity technique (EIT). The physical quantities all over the domain are first compared with the analytical and semi-analytical results to validate accuracy. The effective parameters are then obtained by the present numerical EIT. Since interactions have been considered, we believe our results are more accurate than traditional estimations, such as the generalized self-consistent model (GSCM). Due to the numerical treatment is performed to the present method is more flexible to simulate the effective parameters of clusters with complex geometries. [ABSTRACT FROM AUTHOR]