Formulation and shaping of heterogeneous catalysts are vital in the successful industrial application. Here micro-sized vanadium chromium composite oxides catalysts with the spherical shape were ...prepared via spray drying with colloidal silica as a binder material. The physicochemical properties of catalysts with different Cr/V molar ratios were characterized by XRD, XPS, FT-IR, TPR, and particle size distribution analysis. It was revealed that the addition of Cr inhibited the formation of the crystalline phase V
2
O
5
and decreased the reduction temperature of pentavalent vanadium species, and also resulted in the formation of monoclinic CrVO
4
and a highly dispersed state of vanadia species. VCrO/SiO
2
particles with various Cr/V atomic ratio were studied as catalysts for
p
-chlorotoluene ammoxidation to
p
-chlorobenzonitrile, in which the catalyst with Cr/V ratio of 1 exhibited the best catalytic performance. When the Cr/V ratio was less than 1, mixed phases of orthorhombic CrVO
4
and monoclinic Cr
2
V
4
O
13
were formed and resulted in a low catalytic activity. With the increase of Cr/V ratio, the content of monoclinic CrVO
4
in the catalysts increased, resulting in the catalytic activity of the catalysts improved. However, too large an amount of Cr led to the formation of highly oxidizing hexagonal-Cr
2
O
3
phase, which reduced the selectivity of the catalytic reaction.
Graphic abstract
A honeycomb rotary wheel fabricated from sheet adsorbent of silica gel is a competitive drying facility for air dehumidification in modern drying and air conditioning industries due to its large ...contacting area (3,000 m
2
/m
3
) and the rapid diffusion of the adsorbate compared to silica gel pellets. The delicate preparation procedure of hygroscopic silica gel is paramount for improved adsorption capacity by optimizing the surface area, pore size, and pore volume of silica gel. In this article, silica gel adsorbent in a honeycomb rotary wheel was fabricated by neutralizing the impregnated water glass solution with a modulus of 3.3 on the glass fiber sheet of the honeycomb matrix using CO
2
at different pressure at room temperature instead of corrosive acids. The as-obtained silica gel absorbent was characterized by XRD, scanning electron microscopy (SEM), specific surface area and pore size analysis, and dynamic vapor/gas sorption analysis. The results showed that the as-obtained silica gel adsorbent is uniform in size and tunable in terms of specific surface area, pore size, pore volume, and adsorption capacity by CO
2
pressure. The typical silica gel fabricated by CO
2
of 0.25 MPa with a specific surface area of 764.86 m
2
/g, an average micropore size with a diameter of 2.94 nm, and a pore volume of 0.45 ml/g delivers a saturated adsorption capacity of as high as 287.24 mg/g at RH 50%, which is the best in adsorption performance compared to the previously reported results. This provides a new strategy for environment-friendly manufacturing of silica gel adsorbent in honeycomb rotary wheels for air dehumidification.
Prussian blue (PB) has been broadly recognized as promising cathode materials for sodium-ion batteries (SIBs) due to its large interstitial space and robust frame structure, whereas their ...applications are impeded by unsatisfied long-term cyclability and poor rate capability due to its inherent lattice defects. Herein, we report to fabricate the mesoporous hollow Fe4(Fe(CN)6)3 (one kind of PB) hierarchical nanocrystal architecture by the hydrothermal crystallization and HCl etching of the mesoporous precursor Fe4Fe(CN)63 cubic particles, leading to high crystallinity and large specific surface area. The resultant Fe4Fe(CN)63 cathode for SIBs exhibits a good reversibility and cycling stability with a capacity retention of 75.6 % at 0.5 C after 200 cycles as well as superb rate capability featuring a stable discharge specific capacity of 30.2 mAh g−1 at as high as 10 C, demonstrating the fast kinetics and low polarization of electrochemical reaction, which might be ascribed to the unique architecture and high crystallinity. This offers a new route to designing PB cathode of for SIBs with high rate capabilities.
Spinel nickel cobaltite (NiCo2O4) has been proved to be one of the most promising electrode materials for high performance supercapacitors due to its high theoretic specific capacitance, excellent ...electronic conductivity and good environmental benignity. In this work, the unique NiCo2O4 structure was fabricated hydrothermally via the induction of the reaction temperature and investigated electrochemically as supercapacitor electrode material. The resultant NiCo2O4 electrode with hollow hierarchical microspherical structure as supercapacitor displays excellent capacitive characteristic with higher specific capacitance, better cycling stability and rate capability compared to those with various morphologies, revealing the morphology dependence of the capacitive properties of NiCo2O4 electrode owing to the discrepant electronic conductivity and ion diffusion behavior. Thus, the temperature-induced changes in morphology are potential in the large-scale fabrication of NiCo2O4 electrode materials as supercapacitors.
Tin dioxide (SnO2) have been considered to be a promising anode material for high performance lithium-ion batteries (LIBs) due to its high lithium storage capacity of as high as 1494 mAh g−1, which ...has been impeded greatly due to its large volumetric expansion and low conductivity. Thus, the simple but effective approach for the fabrication of SnO2-based material is ever-urgent. To this end, the mesoporous SnO2@N-rGO nanocomposites were designed and fabricated by a simple and scalable electrostatic self-assembly method and investigated electrochemically as anode for LIBs. The results show that the as-obtained mesoporous SnO2@N-rGO nanocomposites exhibit an excellent cycling stability and outstanding rate capability after an initial activation due to the formation of SEI layer on the surface, which are mainly ascribed to the synergistic effect of nano-SnO2, high conductive N-doped rGO matrix network and rich mesopores. Therefore, this work offers an ingenious strategy to design and fabricate the SnO2-based anode material for high performance lithium-ion batteries.
In recent years, the aqueous zinc-ion batteries (AZIBs) have attracted a remarkable attention due to their low cost, abundance, low toxicity and high safety. MnO2 is considered a potential electrode ...for AZIBs owing to its high theoretical capacity and abundance. However, MnO2 suffers a challenging issue of poor cyclability. Herein, mesoporous Ag-doped γ-MnO2 nanowires were fabricated for the first time by a facile room temperature co-precipitation method under the assistance of Ag+ and investigated electrochemically as cathode for AZIBs. The as-obtained sample electrode delivers a remarkable discharge specific capacity of 978 mAh g-1 at the 65th cycle at a current rate of 0.1 C to be steady at 804 mAh g-1 after 150 cycles and exhibits an excellent rate capability at high C-rate due to the surface-controlled capacitive process of the electrochemical reaction, which is attributed to the unique structure of Ag-doped γ-MnO2 nanowires with rich oxygen defects and crystal water for more active sites and stable structure. This work offers aspiration for the future cathode material engineering as AZIBs.
A novel approach for the fabrications of rGO@S aerogels wherein the sublimed sulfur was impregnated was proposed based on the reduction of the mixed sol of graphene oxide and sulfur followed by the ...freeze-dry. The as-obtained rGO@S aerogels as cathode for lithium sulfur battery were investigated electrochemically. The results show that the rGO@S cathode delivers a high discharge specific capacity of more than 1200 mA h g-1 at a current rate of 0.5 C at room temperature and exhibits good cycling stability and excellent rate capability, indicating the faster kinetics and good reversible thermodynamics for the reaction of sulfur in rGO@S aerogels with lithium in lithium sulfur batteries. This might be attributed to the unique porous structure of rGO@S aerogels in which sulfur could be utilized fully.
NiCo2S4 nanotubes were fabricated time-dependently and hydrothermally at 180 °C and investigated electrochemically as electrode materials. The results show that the as-synthesized NiCo2S4 nanotube as ...anode for lithium ion battery deliver an initial specific capacity of as high as 1780 mAh g-1 at the current density of 100 mA g-1 with poor cycling stability and rate capacity, indicating the potential pseudocapacitive features of NiCo2S4 nanotube. Furthermore, the NiCo2S4 nanotube electrode for supercapacitor demonstrates superior electrochemical performance with superb cycling stability and rate capability, testifying NiCo2S4 nanotube as pseudocapacitance due to the surface diffusion-controlled mechanism of charge storage. These results enable a promise of NiCo2S4 nanotube as intercalation pseudocapacitance rather than as anode for lithium ion battery.
With the further development of ammonia as a new energy fuel, it is urgent to develop a sustainable, accurate and low power consumption detection device for ammonia leakage. In this work, a ...self-powered full-set ammonia leakage monitoring device has been demonstrated, containing power generation system based on a triboelectric nanogenerator (TENG), ammonia sensing system based on carbon nanotube doped polypyrrole (CNTs-PPy) and signal collecting and transmitting system. This equipment has a good application prospect on NH3-fueled ships. The TENG can harvest mechanical energy of vibration during the engine operation to power the whole sensing system. When the external load resistance is 11 MΩ, the output power density can reach to 59.783 W/m3, powered by a five-layer honeycomb structure inspired triboelectric nanogenerator (V-TENG). The ammonia sensing system has the capability to detect ammonia with a low limit of detection (0.2 ppm), short response time (about 90 s), good selectivity, excellent stability and low cost, revealing the potential application of sensor for monitoring NH3 gas under different conditions. Finally, a bluetooth module is assembled into the device, realizing the wireless transmission from the detection module to the computer terminal. The self-powered and wireless full-set device can achieve the long-term and maintenance-free detection of ammonia leakage during the ocean voyage, which will play an important role in the further application of ammonia energy.
A self-powered full-set ammonia leakage monitoring device was fabricated, of which the key parts are power generation system (TENG), ammonia detecting system (CNTs-PPy based sensor) and signal collecting and transmitting system (bluetooth). Display omitted
•By combining with the honeycomb structure triboelectric nanogenerator (TENG), no external power source is demanded.•Via integrated with TENG and Bluetooth, the system is self-powered and wireless and had a superb NH3 sensing.•A series of experiments have been carried out on a scientific research ship, indicating good application prospect.
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