Hydrogen
generated by electrochemical water splitting is an attractive
alternative to fossil fuels. Herein, we developed hollow-like Co2N nanoarrays that serve as electrocatalysts for the hydrogen
evolution reaction (HER) with surface engineering by argon plasma.
The argon plasma-engraved Co2N nanoarrays (Ar-Co2N/CC) represent a dramatic catalytic performance for the HER with
an overpotential of 34 mV at a current density of 10 mA cm–2 in an alkaline electrolyte, as well as outstanding durability of
240 h. Characterization experiments and density functional theory
(DFT) calculations suggest that the enhanced HER activity is due to
the rational coordination environment of Co, which can be tuned by
Ar plasma engraving. Based on our research, one new view for conducting
exceptional catalyst surface modification engineering via plasma engraving
might be established.
The use of atmospheric rotating gliding arc (RGA) plasma is proposed as a facile, scalable and catalyst-free approach to synthesizing hydrogen (H 2 ) and graphene sheets from coalbed methane (CBM). CH 4 is used as a CBM surrogate. Based on a previous investigation of discharge properties, product distribution and energy efficiency, the operating parameters such as CH 4 concentration, applied voltage and gas flow rate can effectively affect the CH 4 conversion rate, the selectivity of H 2 and the properties of solid generated carbon. Nevertheless, the basic properties of RGA plasma and its role in CH 4 conversion are scarcely mentioned. In the present work, a 3D RGA model, with a detailed nonequilibrium CH 4 /Ar plasma chemistry, is developed to validate the previous experiments on CBM conversion, aiming in particular at the distribution of H 2 and other gas products. Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection, electron migration and electron diffusion, and is prominently determined by the variation of the gas flow rate and applied voltage. Subsequently, a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction, taking into consideration the formation and loss pathways of crucial targeted substances (such as CH 4 , C 2 H 2 , H 2 and H radicals) and corresponding contribution rates. Additionally, the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The results show that increasing the applied voltage and decreasing CH 4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets, while the size of the graphene sheets is slightly affected by the change in gas flow rate.
Ammonia is a vital base molecule for modern agriculture and industry. As the commercially-mature approach for NH3 production, the traditional Haber–Bosch process has achieved great success; however, it also suffers...
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