Photocatalytic CO2 reduction by solar energy into carbonaceous feedstock chemicals is recognized as one of the effective ways to mitigate both the energy crisis and greenhouse effect, which fundamentally relies on the development of advanced photocatalysts. Here, the exploration of porous microrod photocatalysts based on novel NiCoO solid solutions derived from bimetallic metal-organic frameworks (MOFs) is reported. They exhibit overall enhanced photocatalytic performance with both high activity and remarkable selectivity for reducing CO2 into CO under visible-light irradiation, which are superior to most related photocatalysts reported. Accordingly, the Ni0.2 -Co0.8 -O microrod (MR-N0.2 C0.8 O) photocatalyst delivers high efficiency for photocatalytic CO2 reduction into CO at a rate up to ≈277 µmol g-1 h-1 , which is ≈35 times to that of its NiO counterpart. Furthermore, they display a high selectivity of ≈85.12%, which is not only better than that of synthesized Co3 O4 (61.25%) but also superior to that of reported Co3 O4 -based photocatalysts. It is confirmed that the Co and Ni species are responsible for CO2 CO conversion activity and selectivity, respectively. In addition, it is verified, by adjusting the Ni contents, that the band structure of NiCoO microrods can be tailored with favorable reduction band potentials, which thus enhance the selectivity toward CO2 photoreduction.
The Autler-Townes effect due to near resonance transition between 4s-4p states in potassium atoms is mapped out in the photo-electron-momentum distribution and manifests itself as a splitting in the photo-electron kinetic energy spectra. The energy splitting fits well with the calculated Rabi frequency at low laser intensities and shows clear deviation at laser intensities above 1.5x10^11 W/cm^2. An effective Rabi frequency formulae including the ionization process explains the observed results. Our results reveal the possibility to tune the effective coupling strength with the cost of the number of level-populations.
A novel traveling-wave Zeeman decelerator based on a double-helix coil geometry capable of decelerating paramagnetic molecules with high efficiency is presented. Moving magnetic traps are generated by applying time-dependent currents through the decelerator coils. Paramagnetic molecules in low-field-seeking Zeeman states are confined inside the moving traps which are decelerated to lower forward velocities. As a prototypical example, we demonstrate the deceleration of OH radicals from an initial velocity of 445 m/s down to various final velocities. The experimental results are analyzed and numerically reproduced with the help of trajectory simulations confirming the phase-space stability and efficiency of the deceleration of the molecules in the new device.
Single-atomic catalysts (SACs) have been emerging as one of excellent candidates in catalysts, owing to their unique merits with extremely high specific surface area as well as remarkably exposed active sites. Herein, we develop a facile strategy based on in-situ gas-phase cation exchange for engineering single-atomic Co on the surface of TiO2 photoanode toward efficient and durable solar water splitting. It is verified that the atomically-dispersed Co with Co-O coordination could optimize the surface electronic structures, enhance the light absorption, promote the photoinduced charge transfer, lower the reaction barrier and accelerate the reaction kinetics, which consequently enable the overall improved photoelectrochemical (PEC) behaviors for photoanodes. As a proof of concept, the as-constructed TiO2-based photoanodes deliver robust stability up to 100 h and high photocurrent density up to 1.47 mA cm−2 at 1.23 V vs. RHE, which are superior to those of pristine TiO2, representing their bright future toward practical applications.
Due to the harmonics produced by inverter supply, the distribution characteristics of rotor copper and iron losses become more complicated in the inverter-fed induction motor (IFIM). To study the distribution characteristics of rotor copper and iron losses of the IFIM, we propose a new method to identify the harmonics of current density in the rotor bar and flux density in the rotor core using one supply cycle's data from the finite element model. The harmonic components in slip frequency are computed by the space-time symmetrical characteristics of the induction motor (IM). And based on a mathematical approach, the higher order frequency harmonics are calculated using data from one supply cycle. Then, we have calculated and analyzed the rotor copper and iron losses of a 5.5 kW IFIM. The experimental validation is performed using the 5.5 kW IFIM under different load conditions. And the calculated and the method motor losses of the 5.5 kW IFIM agree well.
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