Zhenguo Huang

Hydrogen Storage Materials for Mobile and Stationary Applications: Current State of the Art.

One of the limitations to the widespread use of hydrogen as an energy carrier is its storage in a safe and compact form. Herein, recent developments in effective high-capacity hydrogen storage materials are reviewed, with a special emphasis on light compounds, including those based on organic porous structures, boron, nitrogen, and aluminum. These elements and their related compounds hold the promise of high, reversible, and practical hydrogen storage capacity for mobile applications, including vehicles and portable power equipment, but also for the large scale and distributed storage of energy for stationary applications. Current understanding of the fundamental principles that govern the interaction of hydrogen with these light compounds is summarized, as well as basic strategies to meet practical targets of hydrogen uptake and release. The limitation of these strategies and current understanding is also discussed and new directions proposed.

Superior sodium-ion storage performance of Co3O4@nitrogen-doped carbon: derived from a metal–organic framework

Nitrogen-doped carbon coated Co3O4 nanoparticles (Co3O4@NC) with high Na-ion storage capacity and unprecedented long-life cycling stability are reported in this paper. The Co3O4@NC was derived from a metal–organic framework ZIF-67, where the Co ions and organic linkers were, respectively, converted to Co3O4 nanoparticle cores and nitrogen-doped carbon shells through a controlled two-step annealing process. The Co3O4@NC shows a porous nature with a surface area of 101 m2 g−1. When applied as an anode for sodium ion batteries (SIBs), Co3O4@NC delivers a high reversible capacity of 506, 317, and 263 mA h g−1 at 100, 400, and 1000 mA g−1, respectively. A capacity degradation of 0.03% per cycle over 1100 cycles was achieved at a high current density of 1000 mA g−1. The outstanding Na-ion storage performance can be ascribed to the nitrogen-doped carbon coating (NC), which facilitates the capacitive reaction, minimizes the volume changes of Co3O4, and also enhances the electronic conductivity. This work sheds light on how to develop high-performance metal oxide@NC nanocomposites for SIBs.

Edge‐Hydroxylated Boron Nitride Nanosheets as an Effective Additive to Improve the Thermal Response of Hydrogels

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.

Boron-Doped Anatase TiO2 as a High-Performance Anode Material for Sodium-Ion Batteries.

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.

Ammonium octahydrotriborate (NH4B3H8): new synthesis, structure, and hydrolytic hydrogen release.

A metathesis reaction between unsolvated NaB(3)H(8) and NH(4)Cl provides a simple and high-yield synthesis of NH(4)B(3)H(8). Structure determination through X-ray single crystal diffraction analysis reveals weak N-H(δ+)---H(δ-)-B interaction in NH(4)B(3)H(8) and strong N-H(δ+)---H(δ-)-B interaction in NH(4)B(3)H(8)·18-crown-6·THF adduct. Pyrolysis of NH(4)B(3)H(8) leads to the formation of hydrogen gas with appreciable amounts of other volatile boranes below 160 °C. Hydrolysis experiments show that upon addition of catalysts, NH(4)B(3)H(8) releases up to 7.5 materials wt % hydrogen.

Synthesis of Large and Few Atomic Layers of Hexagonal Boron Nitride on Melted Copper

Hexagonal boron nitride nanosheets (h-BNNS) have been proposed as an ideal substrate for graphene-based electronic devices, but the synthesis of large and homogeneous h-BNNS is still challenging. In this contribution, we report a facile synthesis of few-layer h-BNNS on melted copper via an atmospheric pressure chemical vapor deposition process. Comparative studies confirm the advantage of using melted copper over solid copper as a catalyst substrate. The former leads to the formation of single crystalline h-BNNS that is several microns in size and mostly in mono- and bi-layer forms, in contrast to the polycrystalline and mixed multiple layers (1–10) yielded by the latter. This difference is likely to be due to the significantly reduced and uniformly distributed nucleation sites on the smooth melted surface, in contrast to the large amounts of unevenly distributed nucleation sites that are associated with grain boundaries and other defects on the solid surface. This synthesis is expected to contribute to the development of large-scale manufacturing of h-BNNS/graphene-based electronics.

Li2B12H12 · 7NH3: a new ammine complex for ammonia storage or indirect hydrogen storage

A new ammine complex, Li2B12H12·7NH3, that can reversibly release all the NH3 at below 200 °C and reabsorb NH3 at room temperature and 0.5 bar was synthesized and investigated for reversible ammonia storage or indirect hydrogen storage.

Niobium doped anatase TiO2 as an effective anode material for sodium-ion batteries

Sodium-ion batteries are considered to be a promising low-cost alternative to common lithium-ion batteries in the areas where specific energy is less critical. Among all the anode materials studied so far, TiO2 is very promising due to its low operating voltage, high capacity, nontoxicity, and low production cost. Herein, we present Nb-doped anatase TiO2 nanoparticles with high capacity, excellent cycling performance, and excellent rate capability. The optimized Nb-doped TiO2 anode delivers high reversible capacities of 177 mA h g−1 at 0.1C and 108.8 mA h g−1 at 5C, in contrast to 150.4 mA h g−1 at 0.1C and only 54.6 mA h g−1 at 5C for the pristine TiO2. The good performance is likely to be associated with enhanced conductivity and lattice expansion due to Nb doping. These results, in combination with its environmental friendliness and cost efficiency, render Nb-doped TiO2 a promising anode material for high-power sodium-ion batteries.

A simple and efficient way to synthesize unsolvated sodium octahydrotriborate

A simple and efficient way to synthesize unsolvated sodium octahydrotriborate has been developed. This method avoids the use of dangerous starting materials and significantly simplifies the reaction setup, thus enabling convenient large-scale synthesis. The structure of the unsolvated compound has been determined through powder X-ray diffraction.

A new approach to synthesize MoO2@C for high-rate lithium ion batteries

A MoO2@C nanocomposite was prepared using oleic acid to reduce the MoO3 precursor and to simultaneously coat the resultant one-dimensional MoO2 nanorods with carbon layers. The MoO2@C composite has a mesoporous structure with a surface area of 45.7 m2 g−1, and a typical pore size of 3.8 nm. When applied as an anode for lithium ion batteries, the MoO2@C electrode exhibits not only high reversible capacity, but also remarkable rate capability and excellent cycling stability. A high capacity of 1034 mA h g−1 was delivered at 0.1 A g−1. And at a super-high specific current of 22 A g−1, a capacity of 155 mA h g−1 was still obtained. When cycled at 0.5 and 10 A g−1, the Li/MoO2@C half cells retained 861 and 312 mA h g−1 capacity after 140 and 268 cycles, respectively. The mesoporous nature of the MoO2@C nanocomposite and the thin-layer carbon coating are believed to contribute to the enhanced electrochemical performance, which not only feature the efficient four-electron conversion reaction for Li+ storage, but also effectively tolerate volume expansion during the cycling.