The preparation of high performance carbon electrode in electrochemical oxygen generator

The electrochemical oxygen generator has been popularized for its virtues, such as high oxygen concentration output, electricity saving, easy operation and maintenance. The key part of electrochemical oxygen generator is carbon electrode used as the cathode. The preparation of high performance carbon electrode was introduced in this paper. The properties of carbon electrode was tested. The electrochemical oxygen generator using carbon electrode as the cathode was prepared. The oxygen concentration and flow of this machine is hi,yher thnn ｜hal of others in china.

Synergizing high valence metal sites and amorphous/crystalline interfaces in electrochemical reconstructed CoFeOOH heterostructure enables efficient oxygen evolution reaction

Cobalt hydroxide nanosheet is among the most popular oxygen evolution reaction(OER)catalyst yet still suffers from sluggish catalytic kinetics,limited activity,and poor stability.Here,an efficient in situ electrochemical reconstructed CoFe-hydroxides derived OER electrocatalyst was reported.The introduction of Fe promoted the transformation of Co^(2+)into Co^(3+)in CoFehydroxides nanosheet,along with the formation of abundant amorphous/crystalline interfaces.Thanks for the retained nanosheet microstructure,high valence Co^(3+)and Fe^(3+)species,and the amorphous/crystalline heterostructure interfaces,the as-designed electrochemical reconstructed CoFeOOH nanosheet/Ni foam(CoFeOOHNS/NF)electrode delivers 100 mA·cm^(−2) in alkaline at an overpotential of 275 mV and can stably electrocatalyze water oxidation for at least 35 h at 100 mA·cm^(−2).Meanwhile,the alkaline full water splitting electrolyzer achieves a current density of 10 mA·cm^(−2) only at 1.522 V for CoFeOOHNS/NF‖Pt/C/NF,which is much lower than that of Ru/C/NF‖Pt/C/NF(1.655 V@10 mA·cm^(−2)).This work paves the way for in-situ synergetic modification engineering of electrochemical active components.

Methane Conversion to C_2 Hydrocarbons in Solid State Oxide Electrolyte Membrane Reactor

Provskite-type catalysts, Ln0.6 Sr0.4 FexCo1-x O3 (Ln = Nd,Pr, Gd, Sm, La, 0＜x＜1) and Ln0.8Na0.2CoO3(Ln= La,Gd, Sm) were synthesized, their catalytic properties in the oxidative coupling of methane (OCM) were examined in a fixed-bed reactor. The former group presented higher activity in the OCM, but the main product was carbon dioxide. While the later group showed lower activity but much higher selectivity to C2 hydrocarbons compared with the former. Electrochemical measurements were conducted in a solid oxide membrane reactor with La0.8 Na0.2CoO3 as catalyst. The results showed that methane was oxidized to carbon dioxide and ethane by two parallel reactions. Ethane was oxidized to ethene and carbon dioxide. A fraction of ethene was oxidized deeply to carbon dioxide. The total selectivity to C2 hydrocarbons exceeded 70%. Based on the experimental results, a kinetic model was suggested to describe the reaction results.

Hydrogen evolution activity enhancement by tuning the oxygen vacancies in self-supported mesoporous spinel oxide nanowire arrays

The development of facile strategies to tune the oxygen vacancy （OV） content in transition metal oxides （TMOs） is paramount to obtain low-cost and stable electrocatalysts, but still highly challenging. Taking NiC0204 as a model system, we have experimentally established a facile calcination and electrochemical activation （EA） methodology to dramatically increase the concentration of OVs and provide theoretical insight into how the concentration of OVs affects the performance of spinel TMOs towards the electrochemical hydrogen evolution reaction （HER）. A self-supported cathode of OV-rich NiC0204 nanowire arrays was found to exhibit higher HER activity and better stability in alkaline media than its counterparts with fewer OVs. The electrocatalytic HER activity was in good agreement with the increasing concentration of OVs in the studied samples. A large current density of 360 mA.cm-2 was reached with an overpotential of only 317 mV. Additionally, such a facile strategy was able to efficiently generate OVs in other TMOs （e.g., CoFe204 and NiFe204） for enhanced HER performance. In addition, our theoretical results suggest that the increasing OV concentration reduces the adsorption energy of water molecules and their dissociation energy barrier on the surface of the catalyst, thus leading to performance improvement of spinel TMOs toward the electrochemical HER. This work may open a new avenue to increase the concentration of OVs in TMOs in a controlled manner for promising applications in a variety of fields.