scholarly journals A Superaerophobic Bimetallic Selenides Heterostructure for Efficient Industrial-Level Oxygen Evolution at Ultra-High Current Densities

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Jiaxin Yuan ◽  
Xiaodi Cheng ◽  
Hanqing Wang ◽  
Chaojun Lei ◽  
Sameer Pardiwala ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Active Sites ◽  
Electronic Conductivity ◽  
Three Dimensional ◽  
Active Surface ◽  
Alkaline Media ◽  
Active Surface Area ◽  
High Current ◽  
High Electronic Conductivity ◽  
Current Densities

AbstractCost-effective and stable electrocatalysts with ultra-high current densities for electrochemical oxygen evolution reaction (OER) are critical to the energy crisis and environmental pollution. Herein, we report a superaerophobic three dimensional (3D) heterostructured nanowrinkles of bimetallic selenides consisting of crystalline NiSe2 and NiFe2Se4 grown on NiFe alloy (NiSe2/NiFe2Se4@NiFe) prepared by a thermal selenization procedure. In this unique 3D heterostructure, numerous nanowrinkles of NiSe2/NiFe2Se4 hybrid with a thickness of ~ 100 nm are grown on NiFe alloy in a uniform manner. Profiting by the large active surface area and high electronic conductivity, the superaerophobic NiSe2/NiFe2Se4@NiFe heterostructure exhibits excellent electrocatalytic activity and durability towards OER in alkaline media, outputting the low potentials of 1.53 and 1.54 V to achieve ultra-high current densities of 500 and 1000 mA cm−2, respectively, which is among the most active Ni/Fe-based selenides, and even superior to the benchmark Ir/C catalyst. The in-situ derived FeOOH and NiOOH species from NiSe2/NiFe2Se4@NiFe are deemed to be efficient active sites for OER.

Exfoliation of bimetallic (Ni, Co) carbonate hydroxide nanowires by Ar plasma for enhanced oxygen evolution

2020 ◽  
Vol 56 (6) ◽  
pp. 872-875 ◽  
Author(s):  
Hongmei Sun ◽  
Yuanling Miao ◽  
Tao Wu ◽  
Qi Wang
Keyword(s):  
Oxygen Evolution ◽  
Three Dimensional ◽  
Dendritic Structure ◽  
Active Surface ◽  
Oxidation States ◽  
Active Surface Area ◽  
Carbonate Hydroxide ◽  
Ar Plasma ◽  
Electrochemical Active Surface Area ◽  
Thin Nanosheets

Ar plasma exfoliated smooth 1D nanowires of NiCo-LDHs into thin nanosheets forming three-dimensional dendritic structure to expose electrochemical active surface area and more higher oxidation states for enhanced oxygen evolution reaction.

Pt Nanoparticles Decorated on Fe2O3/N, P-Doped Mesoporous Carbon for Enhanced Oxygen Reduction Activity and Durability

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Sabarinathan Ravichandran ◽  
Narayanamoorthy Bhuvanendran ◽  
Kai Peng ◽  
Weiqi Zhang ◽  
Qian Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Alkaline Media ◽  
Active Surface Area ◽  
X Ray

Abstract The Pt–Fe2O3 nanoparticles embedded over N, P-doped carbon (Pt–Fe2O3/NPC) was successfully synthesized by chemical reduction method demonstrating an enhanced electrocatalytic efficacy in alkaline media toward oxygen reduction reaction (ORR). The surface morphology of Pt–Fe2O3/NPC has been characterized by electron microscopy scanning, X-ray diffraction, electron microscopy transmission, Raman spectra, and X-ray photoelectron spectroscopy. The ORR electrocatalytic activity of Pt–Fe2O3/NPC was found to be the superior mass activity of 0.120 mA µg−1, which are almost twice higher than those for Pt–Fe2O3/VC (0.068 mA µg−1) and Pt/C (0.061 mA µg−1) catalysts. The durability tests revealed that the Pt–Fe2O3/NPC exhibited enhanced stability observed from the order of electrochemical active surface area (ECA) loss determined as Pt–Fe2O3/NPC (45.67%) <Pt–Fe2O3/VC (62.5%) <(Pt/C (72.13%) after 5000 cycles. This present investigation unveiled a facile approach to develop the number of active sites with the combination between P–Fe2O3 and N, P-doped carbon for improved electrocatalytic performance toward ORR.

Oxygen Evolution on Perovskite-Type Cobaltite Anodes: An Assessment of Materials Science-Related Aspects

2006 ◽  
Vol 514-516 ◽  
pp. 377-381 ◽  
Author(s):  
Andréy V. Kovalevsky ◽  
D.V. Sviridov ◽  
Vladislav V. Kharton ◽  
E.N. Naumovich ◽  
Jorge R. Frade
Keyword(s):  
Electrochemical Performance ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Vacancy Concentration ◽  
Electronic Conductivity ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Total Conductivity ◽  
Oxygen Vacancy Concentration ◽  
Perovskite Type

Ceramic anodes, made of perovskite-type rare-earth and strontium cobaltites substituted in both sublattices, exhibit a high electrocatalytic activity towards oxygen evolution in alkaline media. This work analyzes the relationships between cation composition, defect structure, electronic conductivity and electrochemical performance for a wide group of perovskite-like cobaltites, including Ln1-yAyCoO3-δ (Ln= Pr, Nd, Sm; A= Sr, Ca; y= 0-0.4), La1-x-ySrxBiyCoO3-δ (x= 0-0.6, y= 0-0.1), La0.7-xSr0.3CoO3-δ (x= 0-0.10), Sr1-xBaxCoO3-δ (x= 0.1-0.2) and SrCo1-yMyO3-δ (M=Fe, Ni, Ti, Cu; y= 0.1-0.6). The materials were prepared by the standard ceramic technique and characterized employing XRD, TGA, iodometric titration, and total conductivity measurements. A relatively high electrochemical performance in alkaline solutions was observed for (La,Sr)CoO3-based compositions with a moderate A-site deficiency. For SrCoO3-based materials, an increase in the oxygen evolution rate was found when co-substituting cobalt with several transition metal cations, such as Fe3+/4+ and Cu2+/3+. The results show that, in general, the key composition-related factors influencing electrochemical activity in alkaline media include the oxygen vacancy concentration, the average positive charge density in the crystal lattice, and possible blocking of active sites on the electrode surface.

scholarly journals Targeted Assembly of Ultrathin NiO/MoS2 Electrodes for Electrocatalytic Hydrogen Evolution in Alkaline Electrolyte

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1547
Author(s):  
Kai Xia ◽  
Meiyu Cong ◽  
Fanfan Xu ◽  
Xin Ding ◽  
Xiaodong Zhang
Keyword(s):  
Current Density ◽  
Active Sites ◽  
Nickel Foam ◽  
Active Surface ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Alkaline Electrolyte ◽  
Active Surface Area ◽  
Dissociation Step ◽  
A Current

The development of non-noble metal catalysts for hydrogen revolution in alkaline media is highly desirable, but remains a great challenge. Herein, synergetic ultrathin NiO/MoS2 catalysts were prepared to improve the sluggish water dissociation step for HER in alkaline conditions. With traditional electrode assembly methods, MoS2:NiO-3:1 exhibited the best catalytic performance; an overpotential of 158 mV was required to achieve a current density of 10 mA/cm2. Further, a synergetic ultrathin NiO/MoS2/nickel foam (NF) electrode was assembled by electrophoretic deposition (EPD) and post-processing reactions. The electrode displayed higher electrocatalytic ability and stability, and an overpotential of only 121 mV was needed to achieve a current density of 10 mA/cm2. The improvement was ascribed to the better catalytic environment, rather than a larger active surface area, a higher density of exposed active sites or other factors. DFT calculations indicated that the hybrid NiO/MoS2 heterostuctured interface is advantageous for the enhanced water dissociation step and the corresponding lower kinetic energy barrier—from 1.53 to 0.81 eV.

Hollow structure engineering of FeCo alloy nanoparticles electrospun in nitrogen-doped carbon enables high performance flexible all-solid-state zinc–air batteries

2020 ◽  
Vol 4 (4) ◽  
pp. 1747-1753 ◽  
Author(s):  
Yuanyuan Ma ◽  
Wenjie Zang ◽  
Afriyanti Sumboja ◽  
Lu Mao ◽  
Ximeng Liu ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Hollow Structure ◽  
Active Surface ◽  
Oxygen Electrode ◽  
Active Surface Area ◽  
Active Components ◽  
Nitrogen Doped Carbon ◽  
Structure Engineering ◽  
Kinetics Of

Hollow structuring of active components is an effective strategy to improve the kinetics of oxygen electrode catalysts, arising from the increased the active surface area, the defects on the exposed surface, and the accessible active sites.

scholarly journals Ultrathin Co–Fe hydroxide nanosheet arrays for improved oxygen evolution during water splitting

RSC Advances ◽  
2017 ◽  
Vol 7 (37) ◽  
pp. 22818-22824 ◽  
Author(s):  
Tingting Zhou ◽  
Zhen Cao ◽  
Heng Wang ◽  
Zhen Gao ◽  
Long Li ◽  
...  
Keyword(s):  
Surface Area ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Three Dimensional ◽  
Fe Doping ◽  
Nanosheet Arrays ◽  
Fe Hydroxide

The Fe-doping of hierarchical Co hydroxide nanosheet arrays (CoyFe1−y(OH)x NSAs) integrated on a three-dimensional electrode is shown to contribute to both increasing the available surface area and number of active sites.

Electrode conduction processes in air plasmas

1962 ◽  
Vol 13 (3) ◽  
pp. 465-477 ◽  
Author(s):  
D. W. George ◽  
H. K. Messerle
Keyword(s):  
Magnetic Field ◽  
Shock Tube ◽  
Current Flow ◽  
Electronic Conductivity ◽  
The Other ◽  
High Current ◽  
Air Plasma ◽  
Air Plasmas ◽  
Current Densities

Using an electrically driven shock tube with initial pressures of 0.1 to 1.0 mm Hg and shock speeds of about Mach 12 to 15, the resistance of an air plasma between two parallel probes has been measured by two different techniques and the results compared. In one, external voltages of from 0 to 100 V were applied to the probes and in the other, electromagnetically induced voltages of from 0 to 25 V were produced by the plasma's motion in a magnetic field of up to 3500 G. In either case the resistance was found to decrease as the current flow increased and was consistent with the equilibrium electronic conductivity of the air plasma at high current densities.

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