Graphene oxide supported cobalt phosphide nanorods designed from a molecular complex for efficient hydrogen evolution at low overpotential

2019 ◽  
Vol 55 (15) ◽  
pp. 2186-2189 ◽  
Author(s):  
Alpesh K. Sharma ◽  
Hemant Joshi ◽  
Kasinath Ojha ◽  
Ajai K. Singh
Keyword(s):  
Graphene Oxide ◽  
Hydrogen Evolution ◽  
Current Density ◽  
Molecular Complex ◽  
Cathodic Current Density ◽  
Cathodic Current ◽  
Cobalt Phosphide ◽  
Low Overpotential

The cathodic current density (cd) of GO-Co2P is 20/100 mA cm−2 at an overpotential of 80/154 mV. At 100 mA cm−2 cd, stability is observed for 70 h.

MOF-derived nanostructured cobalt phosphide assemblies for efficient hydrogen evolution reaction

RSC Advances ◽  
2015 ◽  
Vol 5 (110) ◽  
pp. 90265-90271 ◽  
Author(s):  
Lili Li ◽  
Xingyue Li ◽  
Lunhong Ai ◽  
Jing Jiang
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
High Performance ◽  
Cathodic Current Density ◽  
Cathodic Current ◽  
Zeolitic Imidazolate Framework ◽  
Cobalt Phosphide ◽  
Low Overpotential

Zeolitic imidazolate framework-67 derived nanostructured CoP assemblies exhibited high-performance for electrochemical HER, as manifested by a low overpotential, a large cathodic current density and an excellent durability.

scholarly journals Atomic Pt-Clusters Decoration Triggers a High-Rate Performance on Ni@Pd Bimetallic Nanocatalyst for Hydrogen Evolution Reaction in Both Alkaline and Acidic Medium

2020 ◽  
Vol 10 (15) ◽  
pp. 5155 ◽  
Author(s):  
Dinesh Bhalothia ◽  
Sheng-Po Wang ◽  
Shuan Lin ◽  
Che Yan ◽  
Kuan-Wen Wang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Acidic Medium ◽  
Lattice Mismatch ◽  
Cathodic Current Density ◽  
Green Energy ◽  
High Rate ◽  
Pt Catalyst ◽  
Cathodic Current

The development of inexpensive and highly robust nanocatalysts (NCs) to boost electrochemical hydrogen evolution reaction (HER) strengthens the implementation of several emerging sustainable-energy technologies. Herein, we proposed a novel nano-architecture consisting of a hierarchical structured Ni@Pd nanocatalyst with Pt-clusters decoration on the surface (denoted by Ni@Pd-Pt) for HER application in acidic (0.5 M H2SO4) and alkaline (0.1 M KOH) mediums. The Ni@Pd-Pt NC is fabricated on a carbon black support via a “self-aligned” heterogeneous nucleation-crystal growth mechanism with 2 wt.% Pt-content. As-prepared Ni@Pd-Pt NC outperforms the standard Pt/C (30 wt.% Pt) catalyst in HER and delivers high-rate catalytic performance with an ultra-low overpotential (11.5 mV) at the cathodic current density of 10 mA∙cm−2 in alkaline medium, which is 161.5 mV and 14.5 mV less compared to Ni@Pd (173 mV) and standard Pt/C (26 mV) catalysts, respectively. Moreover, Ni@Pd-Pt NC achieves an exactly similar Tafel slope (42 mV∙dec−1) to standard Pt/C, which is 114 mV∙dec−1 lesser when compared to Ni@Pd NC. Besides, Ni@Pd-Pt NC exhibits an overpotential value of 37 mV at the current density of 10 mA cm−2 in acidic medium, which is competitive to standard Pt/C catalyst. By utilizing physical characterizations and electrochemical analysis, we demonstrated that such an aggressive HER activity is dominated by the increased selectivity during HER due to the reduced competition between intermediate products on the non-homogeneous NC surface. This phenomenon can be rationalized by electron localization owing to the electronegative difference (χPt > χPd > χNi) and strong lattice mismatch at the Ni@Pd heterogeneous binary interfaces. We believe that the obtained results will significantly provide a facile design strategy to develop next-generation heterogenous NCs for HER and related green-energy applications

A robust electrocatalytic activity toward the hydrogen evolution reaction from W/W2C heterostructured nanoparticles coated with a N,P dual-doped carbon layer

2019 ◽  
Vol 55 (65) ◽  
pp. 9665-9668 ◽  
Author(s):  
Quan Zhang ◽  
Fang Luo ◽  
Hao Hu ◽  
Ruizhi Xu ◽  
Konggang Qu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Electrocatalytic Activity ◽  
Carbon Layer ◽  
Cathodic Current Density ◽  
Cathodic Current ◽  
Alkaline Electrolytes

W/W2C heterostructured nanoparticles encapsulated by N,P dual-doped carbon require low overpotentials of 55 mV and 82 mV vs. RHE to achieve cathodic current density of 10 mA cm−2 in acidic and alkaline electrolytes, respectively.

P doped Co2Mo3Se nanosheets grown on carbon fiber cloth as an efficient hybrid catalyst for hydrogen evolution

2017 ◽  
Vol 5 (24) ◽  
pp. 12043-12047 ◽  
Author(s):  
Yaxiao Guo ◽  
Zhaoyang Yao ◽  
Changshuai Shang ◽  
Erkang Wang
Keyword(s):  
Carbon Fiber ◽  
Hydrogen Evolution ◽  
Current Density ◽  
Synergistic Effects ◽  
Cathodic Current Density ◽  
Hybrid Catalyst ◽  
Cathodic Current ◽  
Tafel Slope ◽  
Carbon Fiber Cloth ◽  
Excellent Cycling Stability

Owing to the prominent synergistic effects, P-Co2Mo3Se/CFC hybrid catalyst exhibits a superior HER activity with a small overpotential of 71 mV at cathodic current density of 10 mA cm−2, and a small Tafel slope of 43.6 mV dec−1, as well as excellent cycling stability.

Molybdenum carbide nanocrystal embedded N-doped carbon nanotubes as electrocatalysts for hydrogen generation

2015 ◽  
Vol 3 (11) ◽  
pp. 5783-5788 ◽  
Author(s):  
Kai Zhang ◽  
Yang Zhao ◽  
Diyu Fu ◽  
Yujin Chen
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Molybdenum Carbide ◽  
Hydrogen Generation ◽  
Cathodic Current Density ◽  
Exchange Current ◽  
Exchange Current Density ◽  
Cathodic Current

Highly conductive N-doped carbon nanotubes embedded with molybdenum carbide nanocrystals with a size less than 3 nm exhibit superior activity for the hydrogen evolution reaction, including small overpotential, large cathodic current density and high exchange current density.

Comparative Cathodic Behavior of ~9% Cr and Plain Steel Reinforcement in Concrete

CORROSION ◽  
2012 ◽  
Vol 68 (4) ◽  
pp. 045003-1-045003-10 ◽  
Author(s):  
M. Akhoondan ◽  
A.A. Sagüés
Keyword(s):  
Carbon Steel ◽  
Oxygen Reduction ◽  
Current Density ◽  
Surface Condition ◽  
Corrosion Current ◽  
Reduction Reaction ◽  
Cathodic Current Density ◽  
Cathodic Current ◽  
Steel Rebar ◽  
Cathodic Region

The extent of the oxygen reduction reaction in concrete was evaluated for ~9% Cr rebar approaching the ASTM A1035 specification and compared to that of conventional carbon steel rebar, at ages of up to ~1 year. Cathodic strength was measured by the cathodic current density developed at −0.35 V vs. copper/copper sulfate (Cu/CuSO4 [CSE]) and −0.40 VCSE in cyclic cathodic potentiodynamic polarization tests, both in the as-received condition with mill scale and with scale removed by glass bead surface blasting. In both conditions the ~9% Cr alloy was a substantially weaker cathode, by a factor of several fold, than carbon steel. Within each material, the surface-blasted condition yielded also much lower cathodic current density than the as-received condition. For a small anode-large cathode system with a given anode polarization function, and no important oxygen reduction concentration polarization, the corrosion current was projected to be significantly lower if the cathodic region were ~9% Cr instead of plain steel rebar with comparable surface condition. There was strong correlation between the charge storage capability of the interface and the extent of cathodic reaction of oxygen. The result cannot be ascribed solely to differences in effective surface area between the different materials and conditions.

Controlling factors in localised corrosion morphologies observed for magnesium immersed in chloride containing electrolyte

2015 ◽  
Vol 180 ◽  
pp. 313-330 ◽  
Author(s):  
Geraint Williams ◽  
Nick Birbilis ◽  
H. Neil McMurray
Keyword(s):  
Current Density ◽  
Radial Growth ◽  
Cathodic Current Density ◽  
Nacl Solution ◽  
High Concentration ◽  
Cathodic Current ◽  
Density Distributions ◽  
Filiform Corrosion ◽  
Density Values ◽  
Current Densities

The early stages of localised corrosion affecting magnesium (Mg) surfaces when immersed in aqueous sodium chloride (NaCl) solutions involves the propagation of dark regions, within which both anodic metal dissolution and cathodic hydrogen evolution occur. For nominally “pure” Mg, these dark areas can either take the form of discs which expand radially with time, or filiform-like tracks which lengthen with time. For Mg surfaces which display disc-form corrosion features in concentrated NaCl electrolyte, a transition to filiform corrosion (FFC) is observed as the concentration is decreased, indicating ohmic constraints on radial propagation. A similar effect is observed when Mg specimens of different iron impurity are immersed in a fixed, high concentration NaCl solution, where disc-form corrosion is observed on samples having ≥280 ppm Fe, but FFC predominates at ≤80 ppm Fe. An in situ scanning vibrating electrode technique (SVET) is used to determine current density distributions within the propagating corrosion features. Cathodic current density values of between −100 and −150 A m−2 measured in central areas of disc-like features are sufficient to sustain the radial growth of a local anode at the perimeter of the discs. However, for high purity Mg specimens (≤80 ppm Fe), cathodic current densities of −10 A m−2 or less are measured over FFC affected regions, indicating that linear propagation arises when there is insufficient cathodic current produced on the corroded surface to sustain radial growth. The results are consistent with surface control of localised corrosion propagation in concentrated electrolyte, but ohmic control in dilute, lower conductivity NaCl solution.

scholarly journals Hydrogen Absorption and Desorption in Steel by Electrolytic Charging

2006 ◽  
Vol 15-17 ◽  
pp. 816-821 ◽  
Author(s):  
Geert Mertens ◽  
Lode Duprez ◽  
Bruno C. De Cooman ◽  
Marc Verhaege
Keyword(s):  
Current Density ◽  
Hydrogen Absorption ◽  
Failure Mechanisms ◽  
Great Influence ◽  
Hydrogen Desorption ◽  
Cathodic Current Density ◽  
Cathodic Current ◽  
Charging Current ◽  
Current Densities ◽  
Profound Insight

The presence of hydrogen in steel decreases its toughness and formability leading to hydrogen embrittlement. To understand the failure mechanisms of steel due to the presence of hydrogen, a profound insight in the hydrogen household of the steel is needed. This includes a study of the solubility, the diffusion and the trapping of hydrogen. Next, the absorption and desorption behavior during and after electrolytic charging must be well determined. This was investigated in this research for steels with various types of traps, e.g. dislocations, microcracks, grain boundaries and precipitates such as TiC and Ti4C2S2. The samples were cathodically charged at three different current densities: 0.8mA/cm2; 8.3mA/cm2 and 62.5mA/cm2. It was noticed that the cathodic current density used for hydrogen loading had a great influence on the results. Observation of the samples by scanning electron microscopy (SEM) showed that at the highest current density major damage of the surface had occurred. Hence it was decided to study more systematically the influence of charging current density on the resulting surface aspect and on hydrogen absorption and desorption. The hydrogen charging kinetics, maximum hydrogen solubility and hydrogen desorption behavior have also been evaluated for the different current densities during charging.

Experimental Research on Electroforming Nano-ZrO2 Reinforced Cu-Matrix Composite Aided by Pulse Power

2018 ◽  
Vol 764 ◽  
pp. 95-105
Author(s):  
Zhong Wen Sima ◽  
Zhi Yong Li ◽  
Hong Bin Cui ◽  
Hun Guo
Keyword(s):  
Surface Morphology ◽  
Matrix Composite ◽  
Current Density ◽  
Duty Cycle ◽  
Pulse Frequency ◽  
Cathodic Current Density ◽  
Ultrasonic Power ◽  
Cathodic Current ◽  
Maximum Content ◽  
Cycle Pulse

Prepared the nanoZrO2 reinforced Cu-matrix composite by pulse electroforming. The effects of the content of nanoZrO2 particle in the casting solution, average cathodic current density, duty cycle, pulse frequency and ultrasonic power on the content of nanoZrO2 in the electroforming Cu-matrix composite have been studied. The microhardness and surface morphology of Cu-ZrO2 composite were analyzed. The experimental results demonstrate that the maximum content of nanoZrO2 in the electroforming Cu-ZrO2 composite is 2.94%, microhardness is 492 HV, which is significantly improved compared with pulse pure copper’s 337 HV, when the content of nanoZrO2 is 40 g/L, average cathodic current density is 4A/dm2, duty cycle is 0.2 , pulse frequency is 1100 Hz and ultrasonic power is 20w .The surface of composite prepared by pulse electroforming is more smooth, organization is denser, grain is finer and agglomeration of nanoZrO2 particles is fewer compared with Direct-current electroforming nanoZrO2 reinforced Cu-ZrO2 composite.

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