This paper reports fast microwave hydrothermal synthesis of Ni-based metal−organic frameworks (Ni-MOFs) and their derived yolk−shell NiO structures by direct calcination in air. The molar ratio of the Ni ion to the benzene-1,3,5-tricarboxylic acid (H 3 BTC) ligand has important influence on the NiO morphologies and their electrochemical performances. The obtained yolk−shell NiO microsphere displays a large reversible capacity of 1060 mAh g −1 at a small current density of 0.2 A g −1 and a good high-rate capability when evaluated as an anode for rechargeable lithium-ion batteries. Moreover, the facilitated hydrogen release from ammonia borane (AB) at a lower temperature and the depressed release of undesired volatile byproducts are also observed in the Ni-MOFs supported AB.There is a increasing demand to make efficient use of energy and to find renewable and clean energy sources that can substitute for fossil fuels. 1,2 Energy storage, an important intermediate step toward versatile, clean, and efficient energy applications, has received worldwide concern both in academia and industry. 3−7 Among various candidates of energy storage systems, lithium-ion batteries (LIB) and fuel cells have received considerable attention owing to their high energy densities and environmental benignity. 8−16 LIB, one of the most important rechargeable batteries, have been widely used due to their high energy density and long cycle life. 10,17,18 Metal oxides such as NiO have long been extensively investigated as a potential electrode material for LIBs because of their 2−3 times higher theoretical capacities than commercial graphite electrodes. 19−42 However, their cycling performances and high-rate capabilities are still not satisfactory due to the large volume change associated with lithium insertion and extraction and poor electrical conductivity. 32−38,40−42 Hydrogen is one of the most promising candidates to replace nonrenewable fuel sources because it can react with oxygen to generate electricity with high energy density without byproducts. 43−45 Thus, hydrogen has been regarded as a suitable energy carrier for energy production from primary sources. Advanced materials are highly desired that can store a large amount of hydrogen at mild conditions (common temperature and relatively low pressure) along with a fast release kinetics. 46 Over the past decade, ammonia borane (NH 3 BH 3 , AB) has received much attention as a solid-state hydrogen storage medium because of its satisfactory stability, relatively low molecular mass, and remarkably high energy density. 47−50 However, its practical application is greatly limited by the poor kinetics of hydrogen generation below 85°C and the release of impurities that are detrimental to fuel cells.Metal−organic frameworks (MOFs) are porous materials synthesized by assembling metal ions with organic bridging ligands. 51,52 The metal ions in the MOFs can be thermally transformed into metal oxides, and the C and other elements are oxidized into gas molecules after calcining the MOFs in air at e...

Metal phosphides are a new class of potential high-capacity anodes for lithium ion batteries, but their short cycle life is the critical problem to hinder its practical application. A unique ball-cactus-like microsphere of carbon coated NiP /Ni Sn with deep-rooted carbon nanotubes (Ni-Sn-P@C-CNT) is demonstrated in this work to solve this problem. Bimetal-organic-frameworks (BMOFs, Ni-Sn-BTC, BTC refers to 1,3,5-benzenetricarboxylic acid) are formed by a two-step uniform microwave-assisted irradiation approach and used as the precursor to grow Ni-Sn@C-CNT, Ni-Sn-P@C-CNT, yolk-shell Ni-Sn@C, and Ni-Sn-P@C. The uniform carbon overlayer is formed by the decomposition of organic ligands from MOFs and small CNTs are deeply rooted in Ni-Sn-P@C microsphere due to the in situ catalysis effect of Ni-Sn. Among these potential anode materials, the Ni-Sn-P@C-CNT is found to be a promising anode with best electrochemical properties. It exhibits a large reversible capacity of 704 mA h g after 200 cycles at 100 mA g and excellent high-rate cycling performance (a stable capacity of 504 mA h g retained after 800 cycles at 1 A g ). These good electrochemical properties are mainly ascribed to the unique 3D mesoporous structure design along with dual active components showing synergistic electrochemical activity within different voltage windows.

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