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
Ammonia leaching kinetics of a complex Cu-ore assaying 8.8% Cu and 36.1% Fe was examined. Mineralogical characterization indicated that the major phase of the ore was siderite with chalcopyrite as the major sulfide mi...Ammonia leaching kinetics of a complex Cu-ore assaying 8.8% Cu and 36.1% Fe was examined. Mineralogical characterization indicated that the major phase of the ore was siderite with chalcopyrite as the major sulfide mineral. The effects of parameters such as agitation, temperature, NH3 concentration, particle size and oxygen partial pressure （Po2） were investigated. Under the standard leaching conditions of 125-212 μm particle size, 120 ℃, 1.29 mol/L NH3 and 202 kPa ofpo2, about 83% Cu could be selectively extracted in 2.5 h. However, when using higher NH3 concentration and lower particle size, more than 95% extraction was achieved. The leaching process was found to be surface reaction controlling. The estimated activation energy was （37.6±1.9） kJ/mol and empirical orders of reaction with respect topos and [NH3] were about 0.2 and 1, respectively.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).
文摘Ammonia leaching kinetics of a complex Cu-ore assaying 8.8% Cu and 36.1% Fe was examined. Mineralogical characterization indicated that the major phase of the ore was siderite with chalcopyrite as the major sulfide mineral. The effects of parameters such as agitation, temperature, NH3 concentration, particle size and oxygen partial pressure （Po2） were investigated. Under the standard leaching conditions of 125-212 μm particle size, 120 ℃, 1.29 mol/L NH3 and 202 kPa ofpo2, about 83% Cu could be selectively extracted in 2.5 h. However, when using higher NH3 concentration and lower particle size, more than 95% extraction was achieved. The leaching process was found to be surface reaction controlling. The estimated activation energy was （37.6±1.9） kJ/mol and empirical orders of reaction with respect topos and [NH3] were about 0.2 and 1, respectively.
