Oxygen Reduction Studies on Carbon-supported Pt-M Catalysts (M: Ru, W, Mo)

Maya, Roberto Hernández; González, A.J. Armenta; Reyes, Orlando Ugalde; Guzmán, Mónica; Roquero, Pedro

doi:10.14447/jnmes.v15i3.57

Cited by 2 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…+(R e + R sep ) j + aln( j/j 0 ) [12] Heat balance.-The phase transition by the decomposition of liquid water to gaseous hydrogen and oxygen involves an increase of entropy, which must be spend in terms of the enthalpy of vaporization. In addition, enthalpy of vaporization is consumed by water vapor in the produced gases.…”

Section: Voltagementioning

confidence: 99%

“…10 In the latter case, a porous separator (also commonly referred to as diaphragm) divides the anodic and cathodic compartments. 11 The transition metals from the 8 th to 10 th row of the periodic table are the most suitable metals for the active components of water electrolyzer catalysts, [12][13][14] which can be attributed to their dband character. 15,16 The abundant lower transition metals of the iron group (iron, cobalt, and nickel) are stable in the alkaline regime, [17][18][19] while in the acidic regime, only those of the platinum group show sufficient stability against corrosion in order to enable long-term operation.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Acidic or Alkaline? Towards a New Perspective on the Efficiency of Water Electrolysis

Schalenbach

Tjarks

Carmo

et al. 2016

J. Electrochem. Soc.

275

182

View full text Add to dashboard Cite

Water electrolysis is a promising technology for enabling the storage of surplus electricity produced by intermittent renewable power sources in the form of hydrogen. At the core of this technology is the electrolyte, and whether this is acidic or alkaline affects the reaction mechanisms, gas purities and is of significant importance for the stability and activity of the electrocatalysts. This article presents a simple but precise physical model to describe the voltage-current characteristic, heat balance, gas crossover and cell efficiency of water electrolyzers. State-of-the-art water electrolysis cells with acidic and alkaline electrolyte are experimentally characterized in order to parameterize the model. A rigorous comparison shows that alkaline water electrolyzers with Ni-based catalysts but thinner separators than those typically used is expected be more efficient than acidic water electrolysis with Ir and Pt based catalysts. This performance difference was attributed mainly to a similar conductivity but approximately 38-fold higher diffusivities of hydrogen and oxygen in the acidic polymer electrolyte membrane (Nafion) than those in the alkaline separator (Zirfon filled with a 30 wt% KOH solution In the endeavor to realize an environmentally-benign power supply infrastructure, water electrolysis for the production of hydrogen may prove a key technology for enabling energy conversion on a large scale.1,2 By applying a voltage to two electrodes immersed in an aqueous electrolyte, water can be electrochemically decomposed, evolving hydrogen at the negative pole, the cathode, and oxygen at the positive pole, the anode. During this process, protons or hydroxide ions must pass through the electrolyte to enable the electrochemical reactions at the electrodes. In order to achieve low extents of charge transport losses in electrolyzers, electrolytes with high conductivities are typically used. Such highly conductive electrolytes provide large quantities of ionic charge carriers (protons or hydroxide ions) and are thus either strong bases or acids. The reaction equations in acidic and alkaline aqueous regimes are displayed in Table I.Besides liquid aqueous electrolytes in combination with porous separators, polymer electrolyte membranes (PEMs) are typically used as electrolytes for water electrolysis and to separate the hydrogen and oxygen produced during operation.3 In PEMs, ionizable functional groups are embedded within a polymer matrix providing either mobile protons or hydroxide ions. 4 In an aqueous phase that is separated from the solid polymeric phase 5,6 the protons or hydroxide ions are dissolved but attracted to the oppositely charged ions of the functional group which are covalently bonded to the polymer matrix. As a result, the dissolved ions are captured inside the aqueous phase of the PEM. Hence, an advantage of solid PEMs is that pure water can supplied to the cell, which means that only the components that are in direct contact with the PEM are exposed to its corrosive alkaline or acidic aqueous ph...

show abstract

Section: Voltagementioning

confidence: 99%