Characteristics,materials,and performance of Ru-containing oxide cathode materials for rechargeable batteries

Li-rich Mn-based cathode materials have attracted extensive attention due to their remarkable energy density contributed by additional anionic redox.However,they always suffer from some undesired problems impeding their further commercialization such as irreversible oxygen loss,transition metal migration,sluggish kinetics and so on.Fortunately,the above issues can be relieved effectively when 3d metal Mn is replaced by 4d metal Ru.We focus on the recent progress of Ru-containing cathode materials and make a detailed summary in this review.At first,we attempt to combine and elucidate the relationship between oxygen and Ru redox.Subsequently,the up-to-date materials of Ru-based cathode materials for Li^(+)/Na^(+)batteries are concluded systematically.Afterward,the effects of Ru are discussed in depth including enhancing the reversibility of anionic redox and structural stability,modulating the ratio between cationic and anionic redox,improving the kinetics of Li^(+)/Na^(+),inhibiting the transition metal migration and so on.More importantly,the future designs of Ru-containing cathode materials are also proposed enlighteningly.We hope this review could offer some new perspectives to comprehend the layered oxides involving anionic redox and provide useful guidelines to achieve better Li^(+)/Na^(+)rechargeable batteries.

Construction of one Ru_(2)W_(12)-cluster and six lacunary Keggin tungstoarsenate leading to the larger Ru-containing polyoxometalate photocatalyst

Construction of two Ru^(Ⅲ)cations and six lacunary Keggin fragments resulted in a novel Ru_(2)W_(12)-cluster{(RuO_(6))_(2)(WO_(3))_(12)(H_(2)O)_(12)}bridged polyoxometalate,NaH_(11)[(RuO_(6))(AsW_(9)O_(33))_(3){(W_(6)O_(3))(H_(2)O)_(6)}]_(2)53H_(2)O(NaH_(11)·1·53H_(2)O),which represent the largest cluster in all the Ru-containing polyoxometalates.The most interesting characteristic is that the symmetry-related Ru_(2)W_(12)-cluster-based hexamers contain two windmill-shaped[(RuO_(6))(AsW_(9)O_(33))_(3){(W_(6)O_(3))(H_(2)O)_(6)}]trimers or the Ru_(2)W_(12) cluster was tightly wrapped by six segments of B-β-AsW_(9)O_(33).The other remarkable feature is that there have one intriguing cubane structure:which is composed of the Ru(1,2)and W(1,28,50,51,52,53)atoms.The oxygenation reactions of anilines to azoxybenzenes was evaluated when NaH_(11)·1·53H_(2)O served as effective catalyst by probing various reaction.The inherent redox property of oxygen-rich polyoxometalate surfaces and high photocatalytic activity of the Ru-containing metal cluster imbedded in NaH_(11)·1·53H_(2)O provide sufficient driving force for the photocatalytic transformation from anilines to azoxybenzenes.The oxidation of anilines can be realized with higher selectivity to afford various azoxybenzene compounds.The durability test shows that Ru-doping catalyst displays excellent chemical stability during the photocatalytic process.

Zeolite-seed-directed Ru nanoparticles highly resistant against sintering for efficient nitrogen activation to ammonia

To stabilize Ru nanoparticles against sintering is an urgent problem in the utilization of Ru-based catalysts for NH3 synthesis.In the present study,we used Ru-containing ZSM-5 as seeds to crystallize ZSM-5,and the resulted Ru@ZSM-5 catalyst is highly resistant against Ru sintering.According to the results of diffuse reflectance infrared fourier transform spectroscopy(DRIFTS)and transmission electron microscopy(TEM)analyses,the average size of Ru nanoparticles is around 3.6 nm,which is smaller than that of Ru/ZSM-5-IWI prepared by incipient wetness impregnation.In NH3 synthesis(N2:H2=1:3)at 400℃and 1 MPa,Ru@ZSM-5 displays a formation rate of 5.84 mmolNH3 gcat^-1 h^-1,which is much higher than that of Ru/ZSM-5-IWI(2.13 mmolNH3 gcat^-1 h^-1).According to the results of TEM,N2-temperatureprogrammed desorption(N2-TPD),X-ray photoelectron spectroscopy(XPS)and X-ray absorption fine structure(XAFS)studies,it is deduced that the superior performance of Ru@ZSM-5 is attributable to the small particle size and the ample existence of metallic Ru0 sites.This method of zeolite encapsulation is a feasible way to stabilize Ru nanoparticles for NH3 synthesis.