Zinc‐based electrochemistry is attracting significant attention for practical energy storage owing to its uniqueness in terms of low cost and high safety. However, the grid‐scale application is ...plagued by limited output voltage and inadequate energy density when compared with more conventional Li‐ion batteries. Herein, we propose a latent high‐voltage MnO2 electrolysis process in a conventional Zn‐ion battery, and report a new electrolytic Zn–MnO2 system, via enabled proton and electron dynamics, that maximizes the electrolysis process. Compared with other Zn‐based electrochemical devices, this new electrolytic Zn–MnO2 battery has a record‐high output voltage of 1.95 V and an imposing gravimetric capacity of about 570 mAh g−1, together with a record energy density of approximately 409 Wh kg−1 when both anode and cathode active materials are taken into consideration. The cost was conservatively estimated at <US$ 10 per kWh. This result opens a new opportunity for the development of Zn‐based batteries, and should be of immediate benefit for low‐cost practical energy storage and grid‐scale applications.
High‐voltage and scalable energy storage was demonstrated for a new electrolytic Zn–MnO2 battery system. Because of the new mechanism of two‐electron electrolysis/electrodeposition of Zn/Zn2+ and Mn4+/Mn2+, the system displayed a record‐high output voltage (1.95 V) and energy density (ca. 409 Wh kg−1). In addition, the electrolysis process was modeled by DFT calculations.
A promising high-energy-density material Zhang, Wenquan; Zhang, Jiaheng; Deng, Mucong ...
Nature communications,
08/2017, Letnik:
8, Številka:
1
Journal Article
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Odprti dostop
High-energy density materials represent a significant class of advanced materials and have been the focus of energetic materials community. The main challenge in this field is to design and ...synthesize energetic compounds with a highest possible density and a maximum possible chemical stability. Here we show an energetic compound, 2,2'-bi(1,3,4-oxadiazole)-5,5'-dinitramide, is synthesized through a two-step reaction from commercially available reagents. It exhibits a surprisingly high density (1.99 g cm
at 298 K), poor solubility in water and most organic solvents, decent thermal stability, a positive heat of formation and excellent detonation properties. The solid-state structural features of the synthesized compound are also investigated via X-ray diffraction and several theoretical techniques. The energetic and sensitivity properties of the explosive compound are similar to those of 2, 4, 6, 8, 10, 12-(hexanitrohexaaza)cyclododecane (CL-20), and the developed compound shows a great promise for potential applications as a high-energy density material.High energy density materials are of interest, but density is the limiting factor for many organic compounds. Here the authors show the formation of a high density energetic compound from a two-step reaction between commercially available compounds that exhibit good heat thermal stability and detonation properties.
There is interest in metal single atom catalysts due to their remarkable activity and stability. However, the synthesis of metal single atom catalysts remains somewhat ad hoc, with no universal ...strategy yet reported that allows their generic synthesis. Herein, we report a universal synthetic strategy that allows the synthesis of transition metal single atom catalysts containing Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Pt or combinations thereof. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure spectroscopy confirm that the transition metal atoms are uniformly dispersed over a carbon black support. The introduced synthetic method allows the production of carbon-supported metal single atom catalysts in large quantities (>1 kg scale) with high metal loadings. A Ni single atom catalyst exhibits outstanding activity for electrochemical reduction of carbon dioxide to carbon monoxide, achieving a 98.9% Faradaic efficiency at -1.2 V.
Over the past century, the search for lead-free, environmentally friendly initiating substances has been a highly challenging task in the field of energetic materials. Here, an organic primary ...explosive featuring a fused-ring structure, 6-nitro-7-azido-pyrazol3,4-d1,2,3triazine-2-oxide, was designed and synthesized through a facile two-step reaction from commercially available reagents. This organic initiating substance meets nearly all of the stringent criteria of environmentally friendly primary explosives for commercial applications: it is free of toxic metals and perchlorate, has a high density, high priming ability, unusual sensitivities towards non-explosive stimuli, excellent environmental resistance, decent thermal stability, high detonation performance, satisfactory flowability and pressure durability, and is low-cost and easy to scale-up. These combined properties and performance measures surpass the current and widely used organic primary explosive, DDNP. The fused-ring organic primary explosive reported herein may find real-world application as an initiating explosive device in the near future.
The discovery and identification of novel active sites are paramount for deepening the understanding of the catalytic mechanism and driving the development of remarkable electrocatalysts. Here, we ...reveal that the genuine active sites for the hydrogen evolution reaction (HER) in LaRuSi are Si sites, not the usually assumed Ru sites. Ru in LaRuSi has a peculiar negative valence state, which leads to strong hydrogen binding to Ru sites. Surprisingly, the Si sites have a Gibbs free energy of hydrogen adsorption that is near zero (0.063 eV). The moderate adsorption of hydrogen on Si sites during the HER process is also validated by in situ Raman analysis. Based on it, LaRuSi exhibits an overpotential of 72 mV at 10 mA cm−2 in alkaline media, which is close to the benchmark of Pt/C. This work sheds light on the recognition of real active sites and the exploration of innovative silicide HER electrocatalysts.
Unlike other Ru‐containing compounds whose active sites are Ru sites, the Si sites in LaRuSi function as real active sites. The unusual negative valence Ru in this compound has excessively tight adsorption for hydrogen, according to both theoretical calculations and in situ Raman observations, but the Si sites have excellent hydrogen adsorption properties.
A challenging but pressing task to design and synthesize novel, efficient, and robust pH‐universal hydrogen evolution reaction (HER) electrocatalysts for scalable and sustainable hydrogen production ...through electrochemical water splitting. Herein, we report a facile method to prepare an efficient and robust Ru‐M (M=Ni, Mn, Cu) bimetal nanoparticle and carbon quantum dot hybrid (RuM/CQDs) for pH‐universal HER. The RuNi/CQDs catalysts exhibit outstanding HER performance at all pH levels. The unexpected low overpotentials of 13, 58, and 18 mV shown by RuNi/CQDs allow a current density of 10 mA cm−2 in 1 m KOH, 0.5 m H2SO4, and 1 m PBS, respectively, for Ru loading at 5.93 μgRu cm−2. This performance is among the best catalytic activities reported for any platinum‐free electrocatalyst. Theoretical studies reveal that Ni doping results in a moderate weakening of the hydrogen bonding energy of nearby surface Ru atoms, which plays a critical role in improving the HER activity.
How low can Ru go: A scalable and general synthetic method for the preparation of transition‐metal‐doped RuM/carbon quantum dots (CQDs; M=Ni, Mn, Cu) has been developed through metal‐mediated CQD condensation and carbonization. The low‐ruthenium‐content RuM/CQD catalysts exhibit outstanding activity and stability in catalyzing hydrogen evolution at all pH values.
Within the framework of green chemistry, solvents occupy a strategic place. To be qualified as a green medium, these solvents have to meet different criteria such as availability, non-toxicity, ...biodegradability, recyclability, flammability, and low price among others. Up to now, the number of available green solvents are rather limited. Here we wish to discuss a new family of ionic fluids, so-called Deep Eutectic Solvents (DES), that are now rapidly emerging in the current literature. A DES is a fluid generally composed of two or three cheap and safe components that are capable of self-association, often through hydrogen bond interactions, to form a eutectic mixture with a melting point lower than that of each individual component. DESs are generally liquid at temperatures lower than 100 °C. These DESs exhibit similar physico-chemical properties to the traditionally used ionic liquids, while being much cheaper and environmentally friendlier. Owing to these remarkable advantages, DESs are now of growing interest in many fields of research. In this review, we report the major contributions of DESs in catalysis, organic synthesis, dissolution and extraction processes, electrochemistry and material chemistry. All works discussed in this review aim at demonstrating that DESs not only allow the design of eco-efficient processes but also open a straightforward access to new chemicals and materials.
The stable operation of lithium-based batteries at low temperatures is critical for applications in cold climates. However, low-temperature operations are plagued by insufficient dynamics in the bulk ...of the electrolyte and at electrode|electrolyte interfaces. Here, we report a quasi-solid-state polymer electrolyte with an ionic conductivity of 2.2 × 10
S cm
at -20 °C. The electrolyte is prepared via in situ polymerization using a 1,3,5-trioxane-based precursor. The polymer-based electrolyte enables a dual-layered solid electrolyte interphase formation on the Li metal electrode and stabilizes the LiNi
Co
Mn
O
-based positive electrode, thus improving interfacial charge-transfer at low temperatures. Consequently, the growth of dendrites at the lithium metal electrode is hindered, thus enabling stable Li||LiNi
Co
Mn
O
coin and pouch cell operation even at -30 °C. In particular, we report a Li||LiNi
Co
Mn
O
coin cell cycled at -20 °C and 20 mA g
capable of retaining more than 75% (i.e., around 151 mAh g
) of its first discharge capacity cycle at 30 °C and same specific current.
Great attention has been focused on the design of electrocatalysts to enable electrochemical water splitting-a technology that allows energy derived from renewable resources to be stored in readily ...accessible and non-polluting chemical fuels. Herein we report a bifunctional nanotube-array electrode for water splitting in alkaline electrolyte. The electrode requires the overpotentials of 58 mV and 184 mV for hydrogen and oxygen evolution reactions respectively, meanwhile maintaining remarkable long-term durability. The prominent performance is due to the systematic optimization of chemical composition and geometric structure principally-that is, abundant electrocatalytic active sites, excellent conductivity of metallic 1T' MoS
, synergistic effects among iron, cobalt, nickel ions, and the superaerophobicity of electrode surface for fast mass transfer. The electrode is also demonstrated to function as anode and cathode, simultaneously, delivering 10 mA cm
at a cell voltage of 1.429 V. Our results demonstrate substantial improvement in the design of high-efficiency electrodes for water electrolysis.
The rational design of atomic‐scale interfaces in multiphase nanohybrids is an alluring and challenging approach to develop advanced electrocatalysts. Herein, through the selection of two different ...metal oxides with particular intrinsic features, advanced Co3O4/CeO2 nanohybrids (NHs) with CeO2 nanocubes anchored on Co3O4 nanosheets are developed, which show not only high oxygen vacancy concentration but also remarkable 2D electron gas (2DEG) behavior with ≈0.79 ± 0.1 excess e−/u.c. on the Ce3+ sites at the Co3O4–CeO2 interface. Such a 2DEG transport channel leads to a high carrier density of 3.8 × 1014 cm−2 and good conductivity. Consequently, the Co3O4/CeO2 NHs demonstrate dramatically enhanced oxygen evolution reaction (OER) performances with a low overpotential of 270 mV at 10 mA cm−2 and a high turnover frequency of 0.25 s−1 when compared to those of pure Co3O4 and CeO2 counterparts, outperforming commercial IrO2 and some recently reported representative OER catalysts. These results demonstrate the validity of tailoring the electrocatalytic properties of metal oxides by 2DEG engineering, offering a step forward in the design of advanced hybrid nanostructures.
A novel 2D electron gas (2DEG) behavior, which is realized by integrating CeO2 nanocubes into Co3O4 nanosheets, is demonstrated, and the obtained Co3O4/CeO2 nanohybrids show high electrocatalytic oxygen evolution reaction (OER) performances due to the increased concentration of oxygen vacancies and 2DEG‐promoted high conductivity and electron mobility at the Co3O4–CeO2 interface.
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