Yibo Zhang,Zhihua Li,Liangjun Gong,Xuyu Wang,Peng Hu,Jun Liu
With the advantages of the multiple oxidation states and highly open crystal structures, vanadium-based composites have been considered as the promising cathode materials for aqueous zinc-ion batteries (ZIBs). However, the inherent inferior electrical conductivity, low specific surface area, and sluggish Zn 2+ diffusion kinetics of the traditional vanadium-based oxides have greatly impeded their development. Herein, a novel hierarchical porous spindle-shaped Ag-V 2 O 5 with unique heterostructures was rationally designed via a simple MOF-assisted synthetic method and applied as stable cathode for aqueous ZIBs. The high specific surface area and hierarchically porous superstructures endowed Ag-V 2 O 5 with sufficient electrochemical active sites and shortened the diffusion pathways of Zn 2+ , which was beneficial to accelerate the reversible transport of Zn 2+ and deliver a high specific capacity (426 mA h g −1 at 0.1 A g −1 and 96.5% capacity retention after 100 cycles). Meanwhile, the self-built-in electric fields at the heterointerface of Ag-V 2 O 5 electrode could strengthen the synergistic coupling interaction between Ag and V 2 O 5 , which can effectively enhance the electric conductivity and maintain the structural integrity, resulting in superb rate capability (326.1 mA h g −1 at 5.0 A g −1 ) and remarkable cycling stability (89.7% capacity retention after 2000 cycles at 5.0 A g −1 ). Moreover, the reversible Zn 2+ storage mechanism was further investigated and elucidated by kinetics analysis and DFT calculations.
From the perspective of controlling visible-light-driven catalytic activities of supported metal catalysts by tailoring the band structures of semiconducting supports, we calcined pristine V2O5 in a H2 atmosphere at 250–350 °C to synthesize a series of porous two-dimensional V2O5 nanosheets with narrow bandgaps and rich oxygen vacancies, which supported Co and Ni nanoparticles as catalysts for visible-light-driven on-demand H2 evolution from ammonia borane (NH3BH3) in aqueous solution at 25 °C. The systematic investigations showed that all the catalysts had higher activities under visible light irradiation than in the dark and one Co catalyst exhibited the highest photocatalytic activity with a total turnover frequency (TOF) value of 120.4 min−1, which exceeded the values of all the reported noble metal-free catalysts. Structural characterization indicated that pristine V2O5 and the three post-modified V2O5 species had different bandgaps, valence band positions and concentrations of oxygen vacancies as well as different photocurrent densities, leading to different electron densities of active metal NPs in the supported catalysts with different catalytic activities. This was verified using the UV-vis spectra, valence band X-ray photoelectron spectroscopy, X-ray diffraction patterns and electrochemical characterization of various V2O5 species and the corresponding photocatalytic performance of catalysts.
Zhixiang Ren,Ao Li,Xinyu Lei,Zhengwei Yu,Guangying Wang,Hongliang Zhang,Huan Chen,Yin Wang,Hongming Long
As a mainstream moderate-high temperature (250–420 °C) particulate denitrification catalyst, V 2 O 5 -WO 3 /TiO 2 (VWT) is not applicable to low-temperature (60–150 °C) iron ore sintering flue gas after semi dry/wet desulfurization. In order to improve the NH 3 -deNO x performance of the VWT particle catalyst at low temperatures, a series of powder VWT denitrification catalysts doped with different content of RuO 2 (R-VWT) prepared by the wet co-impregnation method were researched, and found that the particulate catalyst service temperature (about 100 % NO conversion) is lowered from 225 °C (VWT) to below 175 °C by doping 0.5 % RuO 2 . In addition, a series of characterizations indicate that the doped RuO 2 enhances the redox performance of R-VWT and promotes the generation of more surface active intermediate monodentate nitrate, and accelerates the low-temperature surface SCR transient reaction rate.
Xingyun Zhang,Kailimai Su,Yue Hu,Kaiyuan Xue,Yan Wang,Minmin Han,Junwei Lang
The zinc anode mainly faces technical problems such as short circuits caused by the growth of dendrite, low coulomb efficiency, and a short cycle life caused by side reactions, which impedes the rapid development of aqueous zinc-ion batteries (AZIBs). Herein, a common ionic liquid, 1,1-Spirobipyrrolidinium tetrafluoroborate ([SBP]BF4), is selected as a new additive for pure ZnSO4electrolyte. It is found that this additive could regulate the solvation sheath of hydrated Zn2+ions, promote the ionic mobility of Zn2+, homogenize the flux of Zn2+, avoid side reactions between the electrolyte and electrode, and inhibit the production of zinc dendrites by facilitating the establishment of an inorganic solid electrolyte interphase layer. With the 1% [SBP]BF4-modified electrolyte, the Zn||Zn symmetric cell delivers an extended plating/stripping cycling life of 2000 h at 1 mA cm−2, which is much higher than that of the cell without additives (330 h). As a proof of concept, the Zn‖V2O5battery using the [SBP]BF4additive shows excellent cycling stability, maintaining its specific capacity at 97 mAh g−1after 2000 cycles at 5 A g−1, which is much greater than the 46 mAh g−1capacity of the non-additive battery. This study offers zinc anode stabilization through high-efficiency electrolyte engineering.
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