Sodium borohydride (NaBH4) is among the most studied hydrogen storage materials because it is able to deliver high‐purity H2 at room temperature with controllable kinetics via hydrolysis; however, ...its regeneration from the hydrolytic product has been challenging. Now, a facile method is reported to regenerate NaBH4 with high yield and low costs. The hydrolytic product NaBO2 in aqueous solution reacts with CO2, forming Na2B4O7⋅10 H2O and Na2CO3, both of which are ball‐milled with Mg under ambient conditions to form NaBH4 in high yield (close to 80 %). Compared with previous studies, this approach avoids expensive reducing agents such as MgH2, bypasses the energy‐intensive dehydration procedure to remove water from Na2B4O7⋅10 H2O, and does not require high‐pressure H2 gas, therefore leading to much reduced costs. This method is expected to effectively close the loop of NaBH4 regeneration and hydrolysis, enabling a wide deployment of NaBH4 for hydrogen storage.
Coming full circle: A facile method to regenerate NaBH4 with high yield and low cost from its hydrolytic product NaBO2 is presented. This method effectively closes the loop of NaBH4 hydrolysis and regeneration and therefore enables a wide deployment of NaBH4 for hydrogen storage.
Boron's unique position in the Periodic Table, that is, at the apex of the line separating metals and nonmetals, makes it highly versatile in chemical reactions and applications. Contemporary demand ...for renewable and clean energy as well as energy‐efficient products has seen boron playing key roles in energy‐related research, such as 1) activating and synthesizing energy‐rich small molecules, 2) storing chemical and electrical energy, and 3) converting electrical energy into light. These applications are fundamentally associated with boron's unique characteristics, such as its electron‐deficiency and the availability of an unoccupied p orbital, which allow the formation of a myriad of compounds with a wide range of chemical and physical properties. For example, boron's ability to achieve a full octet of electrons with four covalent bonds and a negative charge has led to the synthesis of a wide variety of borate anions of high chemical and electrochemical stability—in particular, weakly coordinating anions. This Review summarizes recent advances in the study of boron compounds for energy‐related processes and applications.
The fifth element: Boron has a unique position in the Periodic Table—directly at the apex of the line separating metals and nonmetals. This Review highlights the critical role of boron and boron compounds in the fields of energy conversion and storage, and demonstrates the versatility and potential of boron for energy‐related research.
Upon flowing hot steam over hexagonal boron nitride (h‐BN) bulk powder, efficient exfoliation and hydroxylation of BN occur simultaneously. Through effective hydrogen bonding with water and ...N‐isopropylacrylamide, edge‐hydroxylated BN nanosheets dramatically improve the dimensional change and dye release of this temperature‐sensitive hydrogel and thereby enhance its efficacy in bionic, soft robotic, and drug‐delivery applications.
Pristine and boron-doped anatase TiO2 were prepared via a facile sol–gel method and the hydrothermal method for application as anode materials in sodium-ion batteries (SIBs). The sol–gel method leads ...to agglomerated TiO2, whereas the hydrothermal method is conducive to the formation of highly crystalline and discrete nanoparticles. The structure, morphology, and electrochemical properties were studied. The crystal size of TiO2 with boron doping is smaller than that of the nondoped crystals, which indicates that the addition of boron can inhibit the crystal growth. The electrochemical measurements demonstrated that the reversible capacity of the B-doped TiO2 is higher than that for the pristine sample. B-doping also effectively enhances the rate performance. The capacity of the B-doped TiO2 could reach 150 mAh/g at the high current rate of 2C and the capacity decay is only about 8 mAh/g over 400 cycles. The remarkable performance could be attributed to the lattice expansion resulting from B doping and the shortened Li+ diffusion distance due to the nanosize. These results indicate that B-doped TiO2 can be a good candidate for SIBs.
Creating vacancy is often highly effective in enhancing the hydrogen evolution performance of transition metal-based catalysts. Vacancy-rich Ni nanosheets have been fabricated via topochemical ...formation of two-dimentional (2D) Ni
2
B on graphene precursor followed by boron leaching. Anchored on graphene, a few atomic layered Ni
2
B nanosheets are first obtained by reduction and annealing. Large number of atomic vacancies are then generated in the Ni
2
B layer via leaching boron atoms. When used for hydrogen evolution reaction (HER), the vacancy-rich Ni/Ni(OH)
2
heterostructure nanosheets demonstrate remarkable performance with a low overpotential of 159 mV at a current density of 10 mA·cm
−2
in alkaline solution, a dramatic improvement over 262 mV of its precursor. This enhancement is associated with the formation of vacancies which introduce more active sites for HER along Ni/Ni(OH)
2
heterointerfaces. This work offers a facile and universal route to introduce vacancies and improve catalytic activity.
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Two-dimensional (2D) materials have shown outstanding properties that make them the materials of choice for future semiconductor and flexible nanoelectronics. Hexagonal boron nitride ...nanosheet (BNNS) is one of the most studied 2D materials due to its extraordinary properties and potential applications. The synthesis of large, homogeneous, and few-layered BNNS, however, remains challenging. Among the various synthetic routes, chemical vapour deposition (CVD) is preferred on the grounds of its potential to yield large BNNS with controllable atomic layers and minimal contamination. We thus devote this review to the CVD growth of BNNS, and its characterization and applications. The recent progresses in the CVD growth of BNNS is firstly summarized from the aspects of precursors, substrates, growth mechanisms, and transfer techniques. This review then moves on to the characterization of few-atomic-layered h-BN sheets, covering a variety of microscopic and spectroscopic techniques that have proved useful for assessing the quality of BNNS. The applications of the BNNS are also summarized. This review is expected to instigate new methods and improvements in relation to the CVD growth of BNNS, which has enabled exceptional performance as a key component of nanoscale electronics.
Mg2+/Li+ hybrid batteries have recently been constructed combining a Mg anode, a Li+-intercalation electrode, and an electrolyte containing both Mg2+ and Li+. These batteries have been reported to ...outperform all the previously reported magnesium batteries in terms of specific capacity, cycling stability, and rate capability. Herein, we report the outstanding electrochemical performance of Mg2+/Li+ hybrid batteries consisting of a one-dimensional mesoporous TiO2(B) cathode, a Mg anode, and an electrolyte consisting of 0.5 mol L–1 Mg(BH4)2 + 1.5 mol L–1 LiBH4 in tetraglyme. A highly synergetic interaction between Li+ and Mg2+ ions toward the pseudo-capacitive reaction is proposed. The hybrid batteries show superior rate performance with 130 mAh g–1 at 1 C and 115 mAh g–1 at 2 C, together with excellent cyclability up to 6000 cycles.
A facile two-step annealing process is applied to synthesize nanocage Co3O4, using cobalt-based metal-organic framework as precursor and template. The as-obtained nanocages are composed of numerous ...Co3O4 nanoparticles. N2 adsorption–desorption isotherms show that the as-obtained Co3O4 has a porous structure with a favorable surface area of 110.6 m2 g−1. Electrochemical tests show that nanocage Co3O4 is a potential candidate as anode for lithium-ion batteries. A reversible specific capacity of 810 mAh g−1 was obtained after 100 cycles at a high specific current of 500 mA g−1. The material also displays good rate capability, with a reversible capacity of 1069, 1063, 850, and 720 mAh g−1 at specific current of 100, 200, 800, and 1000 mA g−1, respectively. The good electrochemical performance of nanocage Co3O4 can be attributed to its unique hierarchical hollow structure, which is maintained during electrochemical cycling.
Hierarchical Co3O4 nanocages are synthesized via a two-step annealing process. When applied as an anode material for LIBs, high capacity, good cycling stability, and high rate capability is observed. Display omitted
•Co-MOF is converted to nanocage Co3O4 by two-step thermal annealing.•As-obtained nanocages are composed of Co3O4 nanoparticles with porous nature.•Nanocage Co3O4 exhibits good rate capability and cycling stability as LIB anode.
Porous carbon-metal oxide hybrid materials are advanced functional composites with great potential for use in high energy density supercapacitors. Here we describe a hybrid structure composed of ...two-dimensional (2D) NiCo2O4 nanosheets synthesized on polyhedral-shaped nanoporous carbon (NC) particles. The NC particles were derived from the carbonization of zeolitic imidazole frameworks (ZIF-8). Supercapacitor devices assembled using NiCo2O4-NC nanoparticles had excellent capacitive properties with energy densities up to 28 W h kg-1 and power densities up to 8.5 kW kg-1.
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