Rational design and bottom-up synthesis based on the structural topology is a promising way to obtain two-dimensional metal–organic frameworks (2D MOFs) in well-defined geometric morphology. Herein, a topology-guided bottom-up synthesis of a novel hexagonal 2D MOF nanoplate is realized. The hexagonal channels constructed via the distorted (3,4)-connected Ni2(BDC)2(DABCO) (BDC = 1,4-benzene­dicarboxylic acid, DABCO = 1,4-diazabicyclo[2.2.2]­octane) framework serve as the template for the specifically designed morphology. Under the inhibition and modulation of pyridine through a substitution–suppression process, the morphology can be modified from hexagonal nanorods to nanodisks and to nanoplates with controllable thickness tuned by the dosage of pyridine. Subsequent pyrolysis treatment converts the nanoplates into a N-doped Ni@carbon electrocatalyst, which exhibits a small overpotential as low as 307 mV at a current density of 10 mA cm–2 in the oxygen evolution reaction.

No abstract

Layered metal hydroxides (LMHs) are regarded as a novel and important class of inorganic functional materials. They have unique layered structure and variable chemical compositions that can be readily tuned. In this review, summarized are the recent advances of synthetic routes to the LMHs with designed morphology, composition, and function for electrocatalysis. Versatile products can be readily derived by hybridization, anion‐exchange, surface modification, self‐assembly, etc. More importantly, LMHs can be artificially exfoliated into unilamellar nanosheets with a molecular‐level thickness of about 1 nm versus 2D lateral size in submicrometer or micrometer scale. Molecular‐scale assembly can be then applied to fabricate superlattice‐like composites and functional nanofilms with high quality. The hydroxides can be transformed into oxides, nitrides, or other compounds via different preparation procedures, which can further extend their application prospects. In this regard, the most promising electrocatalysis‐related applications of LMHs and their derivatives are reviewed, such as oxygen evolution reaction, oxygen reduction reaction, hydrogen evolution reaction, CO2 reduction reaction, alcohol or urea electrooxidation, etc. At last, future challenges are also discussed from the aspect of synthesis and application, as well as encouraging advancements are anticipated.

No abstract

Unique high-capacity MnO2/porous graphitic carbon (MnO2/PGC) composites were fabricated by a mild and efficient in situ precipitation approach using PGC derived from coal tar pitch as the carbonaceous precursor and KMnO4 as the manganese source. MnO2/PGC composites with reasonable surface areas (190–229 m2 g–1) retain the superior structure of interconnected nanopores and graphitic crystallite from PGC and contain evenly distributed MnO2 modified on the surface of the carbon skeleton in PGC, which can not only provide sufficient active sites for lithium-ion storage but also enhance electron transport capability and efficient lithium-ion diffusion capability. As a result of the synergistic effect of PGC and MnO2, MnO2/PGC composites as anode materials in lithium-ion batteries (LIBs) exhibit excellent reversible capacity, rate performance, and cycling stability. In particular, the MnO2/PGC-36 composite possesses a high initial reversible capacity of 1516 mAh g–1 at a current density of 0.05 A g–1 and an average reversible capacity of 399 mAh g–1 at a high rate of 5.00 A g–1. Moreover, such a MnO2/PGC-36 composite also exhibits a superior long-term cycling stability, with over 90.0% capacity retention after 400 cycles. These outstanding electrochemical performances demonstrate that the MnO2/PGC composite can be a promising anode material in LIBs for further practical application.