Co-synthesis of vertical graphene nanosheets and high-value gases using inductively coupled plasma enhanced chemical vapor deposition

One-step controllable synthesis of vertical graphene nanosheets （VGs） and high-value gases was achieved using inductively coupled plasma enhanced chemical vapor deposition （ICPECVD）. The basic physical properties of the ICPECVD process were revealed via electrical diagnosis and optical emission spectroscopy. The coil current and voltage increased linearly with the augmenting of injected power, and CH, C2, H2 and H were detected at a wavelength from 300 to 700 nm, implying the generation of abundant graphene-building species. The morphology and structure of solid carbon products, graphene nanosheets, were systemically characterized in terms of the variations of operating conditions, such as pressure, temperature, gas proportion, etc. The results indicated that an appropriate operating condition was indispensable for the growth process of graphene nanosheets. In the present work, the optimized result was achieved at the pressure, heating temperature, applied power and gas proportion of 600 mTorr, 800 ~C, 500 W and 20：20：15, respectively, and the augmenting of both CH4 and H2 concentrations had a positive effect on the etching of amorphous carbon. Additionally, H2 and C2 hydrocarbons were detected as the main exhaust gases. The selectivity of H2 and C2H2, measured in exhaust gases, reached up to 52% and 8%, respectively, which implied a process of free radical reactions and electron collision dissociation. Based on a comprehensive investigation of spectral and electrical parameters and synthesized products, the reaction mechanism of collision, dissociation, diffusion, etc, in ICPECVD could be speculated, providing a probable guide for experimental and industrial applications.

Non-Traveling Wave Solutions for the (1 + 1)-Dimensional Burgers System by Riccati Equation Mapping Approach

Starting from the symbolic computation system Maple and Riccati equation mapping approach and a linear variable separation approach, a new family of non-traveling wave solutions of the (1 + 1)-dimensional Burgers system is derived.

Effect of Non-Convective Zone Thickness on Thermal Efficiency of Salt Gradient Solar Ponds

An improved radiation transmission and thermal efficiency model for solar ponds has been proposed based on both the Hull Model and Wang/Seyed-Yagoobi Model in this paper.The new model is more accurate to actual measured conditions because multiple reflections and turbidity effects are included.Absorption penetration,thermal conductivity loss and thermal efficiency under different Non-Convective Zone thicknesses are numerically analyzed and thoroughly discussed.The results show thatΔT/I0 plays a critical role for the thermal efficiency of solar pond.Furthermore,it is found through calculation that there is an optimum thickness of the Non-Convective Zone.When the Non-Convective Zone thickness is less than this critical threshold,both temperature and thermal efficiency are decreased with increasing turbidity.However,when the Non-Convective Zone thickness is greater than this critical threshold,the increasing turbidity within a certain range will be beneficial to improve the thermal efficiency of solar pond.In addition,optimum Non-Convective Zone thickness is also related to the temperature,turbidity,salinity variation and bottom reflectivity.

Butler matrix enabled multi-beam optical phased array for two-dimensional beam-steering and ranging

Based on the wavelength transparency of the Butler matrix(BM)beamforming network,we demonstrate a multibeam optical phased array(MOPA)with an emitting aperture composed of grating couplers at a 1.55μm pitch for wavelength-assisted two-dimensional beam-steering.The device is capable of simultaneous multi-beam operation in a field of view(FOV)of 60°×8°in the phased-array scanning axis and the wavelength-tuning scanning axis,respectively.The typical beam divergence is about 4°on both axes.Using multiple linearly chirped lasers,multibeam frequency-modulated continuous wave(FMCW)ranging is realized with an average ranging error of 4 cm.A C-shaped target is imaged for proof-of-concept 2D scanning and ranging.

Plasma-enhanced catalytic activation of CO_(2) in a modified gliding arc reactor

For the first time,this paper demonstrates a synergistic effect from the combination of a gliding arc discharge plasma with a photocatalyst TiO_(2) for CO_(2) dissociation.The effects of adding a tray downstream the discharge and the combination of the catalyst with plasma have been investigated.Two different combination modes of plasma catalysis,i.e.,in-plasma catalysis and post-plasma catalysis,have been evaluated with the emphasis on the analysis of potential mechanisms.The results show that modifying the gliding arc reactor by the addition of a tray can enhance the fraction of gas treated by plasma,thus improv-ing the reaction performance.An exceptional synergistic effect of combining the gliding arc discharge with TiO_(2) for CO_(2) activation forms in the in-plasma catalysis mode.The presence of TiO_(2) significantly enhances the CO_(2) conversion by 138% and the energy efficiency by 133%at a flow rate of 2 L/min.The plasma activation effect,which produces energetic electrons that can create the electron-hole pairs on the catalyst surface,is believed to be the major contributor to the generation of the plasma catalysis synergy.This mechanism has been further evidenced by the negligible influence of the post-plasma catalysis on the reaction performance.