In this work,phase and morphology-tuned MoO_(3) nanostructures are synthesized through a novel modified co-precipitation method,and their electrochemical properties are investigated.For the first time,such a simple su...In this work,phase and morphology-tuned MoO_(3) nanostructures are synthesized through a novel modified co-precipitation method,and their electrochemical properties are investigated.For the first time,such a simple surfactant-assisted synthesis process aided by minor temperature variations is reported which results in phase transition of the nanoparticles from h-MoO_(3) nano-rods to a-MoO_(3) nano-flakes.The nanostructures thus developed are highly porous and crystalline with significantly large specific surface area as compared to previous literature.The theoretical bandgap energy of the optimized sample calculated using Perdew-Zunger local density approximation(LDA) is in good agreement with the experimental findings.An overall structural,morphological,and surface-behavioural analysis predicts the electrochemical superiority in 2D a-MoO_(3).The cyclic voltammetry and galvano-potentiometry measurements of 2D a-MoO_(3) in the potential window of-0.6 V to +0.2 V present the highest pseudosupercapacitive response with a maximum specific capacitance of 829 F g^(-1)at 2 A g^(-1)as compared to h-MoO_(3) (452 F g^(-1)) and h@a-MoO_(3) (783 F g^(-1)).Thus,the MoO_(3) 2D nanostructures synthesized through our novel synthesis technique display excellent specific capacitance as compared to previous reported data.Additionally,a-MoO_(3) exhibits a galvanostatic charging-discharging cyclic stability of about 91%after 2000 cycles,indicating that it can serve as an excellent electrode material for supercapacitors.A solid-state asymmetric supercapacitor device is successfully constructed using a-MoO_(3) which can light up 4 red LEDs for 10 s.The specific energy density of the device reaches a maximum value of 36.3 W h kg^(-1)at the power density of 50 W kg^(-1).展开更多
Thermal maturity is commonly assessed by various geochemical screening methods(e.g.,pyrolysis and organic petrology).In this contribution,we attempt to establish an alternative approach to estimating thermal maturity ...Thermal maturity is commonly assessed by various geochemical screening methods(e.g.,pyrolysis and organic petrology).In this contribution,we attempt to establish an alternative approach to estimating thermal maturity with Raman spectroscopy,using 24 North American oil shale samples with thermal maturity data generated by vitrinite reflectance(VRo%)and pyrolysis(Tmax)-based maturity calculation(VRe%).The representative shale samples are from the Haynesville(East Texas),Woodford(West Texas),Eagle Ford and Pearsall(South Texas)Formations,as well as Gothic,Mancos,and Niobrara Formation shales(all from Colorado).The Raman spectra of disordered carbonaceous matter(D1 and G bands separation)of these samples were directly obtained from the rock chips without prior sample preparation.Using the Gaussian and Lorentzian distribution approach,thermal maturities from VR were correlated with carbon G and D1.We found that the Raman band separation(RBS)displayed a better correlation for equivalent VRe%than vitrinite reflectance VRo%.The RBS(D1–G)distance versus total organic carbon,free hydrocarbons from thermal extraction(S1),and the remaining hydrocarbon generating potential(S2)indicate that the RBS(D1–G)distance is also related to kerogen type.Data presented here from three methods of maturity determination of shale demonstrate that Raman spectroscopy is a quick and valid approach to thermal maturity assessment.展开更多
文摘In this work,phase and morphology-tuned MoO_(3) nanostructures are synthesized through a novel modified co-precipitation method,and their electrochemical properties are investigated.For the first time,such a simple surfactant-assisted synthesis process aided by minor temperature variations is reported which results in phase transition of the nanoparticles from h-MoO_(3) nano-rods to a-MoO_(3) nano-flakes.The nanostructures thus developed are highly porous and crystalline with significantly large specific surface area as compared to previous literature.The theoretical bandgap energy of the optimized sample calculated using Perdew-Zunger local density approximation(LDA) is in good agreement with the experimental findings.An overall structural,morphological,and surface-behavioural analysis predicts the electrochemical superiority in 2D a-MoO_(3).The cyclic voltammetry and galvano-potentiometry measurements of 2D a-MoO_(3) in the potential window of-0.6 V to +0.2 V present the highest pseudosupercapacitive response with a maximum specific capacitance of 829 F g^(-1)at 2 A g^(-1)as compared to h-MoO_(3) (452 F g^(-1)) and h@a-MoO_(3) (783 F g^(-1)).Thus,the MoO_(3) 2D nanostructures synthesized through our novel synthesis technique display excellent specific capacitance as compared to previous reported data.Additionally,a-MoO_(3) exhibits a galvanostatic charging-discharging cyclic stability of about 91%after 2000 cycles,indicating that it can serve as an excellent electrode material for supercapacitors.A solid-state asymmetric supercapacitor device is successfully constructed using a-MoO_(3) which can light up 4 red LEDs for 10 s.The specific energy density of the device reaches a maximum value of 36.3 W h kg^(-1)at the power density of 50 W kg^(-1).
基金partially supported by the Graduate Student Research Grants from the Gulf Coast Association of Geological Societies (GCAGS)American Association of Petroleum Geologist (AAPG)by the University of Texas at Arlington and by the Pioneer Natural Resources
文摘Thermal maturity is commonly assessed by various geochemical screening methods(e.g.,pyrolysis and organic petrology).In this contribution,we attempt to establish an alternative approach to estimating thermal maturity with Raman spectroscopy,using 24 North American oil shale samples with thermal maturity data generated by vitrinite reflectance(VRo%)and pyrolysis(Tmax)-based maturity calculation(VRe%).The representative shale samples are from the Haynesville(East Texas),Woodford(West Texas),Eagle Ford and Pearsall(South Texas)Formations,as well as Gothic,Mancos,and Niobrara Formation shales(all from Colorado).The Raman spectra of disordered carbonaceous matter(D1 and G bands separation)of these samples were directly obtained from the rock chips without prior sample preparation.Using the Gaussian and Lorentzian distribution approach,thermal maturities from VR were correlated with carbon G and D1.We found that the Raman band separation(RBS)displayed a better correlation for equivalent VRe%than vitrinite reflectance VRo%.The RBS(D1–G)distance versus total organic carbon,free hydrocarbons from thermal extraction(S1),and the remaining hydrocarbon generating potential(S2)indicate that the RBS(D1–G)distance is also related to kerogen type.Data presented here from three methods of maturity determination of shale demonstrate that Raman spectroscopy is a quick and valid approach to thermal maturity assessment.
