Isoelectric points and points of zero charge of metal (hydr)oxides: 50years after Parks' review

Kosmulski, Marek

doi:10.1016/j.cis.2016.10.005

Cited by 412 publications

(258 citation statements)

References 599 publications

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“…The IEP values for Co 3 O 4 (7.5), Fe 3 O 4 (6.6), NiCo 2 O 4 (9.1), NiFe 2 O 4 (7.6), and NiO (8.8) are consistent with previously reported values from the literature. [29][30][31] We expect the IEP to primarily reflect the surface of the catalysts and to be less sensitive to bulk composition. De Faria et al 27 showed that for NiCo oxides the point of zero charge (pzc) correlates with surface segregation of Ni in the oxides, as assessed by XPS.…”

Section: Resultsmentioning

confidence: 99%

Optimized Nickel-Cobalt and Nickel-Iron Oxide Catalysts for the Hydrogen Evolution Reaction in Alkaline Water Electrolysis

Faid

Barnett

Seland

et al. 2019

J. Electrochem. Soc.

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Ni and Ni-doped with transition metals (TM) such as Fe and Co represent the most suitable electrodes for hydrogen evolution reaction (HER) in alkaline media. Various compositions of co-precipitated Ni 1+x Fe 2−x O 4 and Ni 1+y Co 2−y O 4 nanoparticles were investigated. The intrinsic HER catalytic activity is the same for all the catalysts, which we relate to similar values of the iso-electric point (IEP). However, the mass catalytic activity of the catalysts changes through a modification of the electrochemical surface area. Fractional reaction orders for hydrogen evolution revealed in all catalyst compositions are due to double layer effects and surface acid-base equilibria. Reaction order and Tafel slope of the catalysts are compatible with electrochemical adsorption as the rate-determining step for the HER. Tafel slopes were also evaluated independently from impedance spectroscopy, in good agreement with the polarization curves. Electrodes prepared from catalyst inks containing an anion-exchange ionomer displayed inferior catalytic activity for the HER as compared to electrodes prepared with Nafion in the ink. Chronoamperometry confirmed the sustained superior hydrogen kinetics over time of NiFe 2 O 4 and NiCo 2 O 4 composition over that of NiO. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.241.231.30 Downloaded on 2019-05-09 to IP F520 Journal of The Electrochemical Society, 166 (8) F519-F533 (2019) ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.241.231.30 Downloaded on 2019-05-09 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.241.231.30 Downloaded on 2019-05-09 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.241.231.30 Downloaded on 2019-05-09 to IP

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Section: Resultsmentioning

confidence: 99%

Optimized Nickel-Cobalt and Nickel-Iron Oxide Catalysts for the Hydrogen Evolution Reaction in Alkaline Water Electrolysis

Faid

Barnett

Seland

et al. 2019

J. Electrochem. Soc.

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“…For Qz and Il, zeta potential measurements at pH < 2, which would have been required to determine the IEP, were not possible because of the limitations of the device. From that we concluded that the IEPs of Qz and Il, if they existed, were below pH = 2 (Kosmulski, 2016;Sondi, Biscan, & Pravdic, 1996). Zeta potential measurements of EPS-associated Il and Qz revealed no clear increases in the zeta potentials compared with EPS-free samples (Supporting Information Figure S3).…”

Section: Characterization Of the Microaggregate-forming Materials (mentioning

confidence: 88%

Formation of mineral–mineral and organo–mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances

Guhra

Ritschel

Totsche

2019

European J Soil Science

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Structures of colloidal compounds in soil, including organo–mineral and mineral–mineral associations, are considered as composite building units (CBUs) that may combine into soil microaggregates. Despite the ubiquitous occurrence of CBUs, the major formation mechanisms are rather obscure and little is known about whether they form primarily during weathering of the parent rocks or by aggregation processes from the soil suspension. We studied the formation of CBUs from suspensions composed of minerals and organic matter typical for temperate soils (i.e. quartz, goethite, illite and extracellular polymeric substances [EPS]). Without EPS, we found CBUs formed as mineral–mineral associations by hetero coagulation of illite and quartz that is bridged by goethite. The presence of EPS, in contrast, led to the formation of a stable suspension of clay‐sized CBUs with no involvement of quartz. We explained this by the rapid formation of organo–mineral CBUs made of EPS‐associated goethite and EPS‐associated illite. The sorption of EPS to goethite screened its surface charge, thereby reducing the electrostatic attraction between goethite and illite. This interaction effectively impeded the formation of mineral–mineral CBUs. Moreover, interactions of EPS with goethite resulted in a marked decrease of the phosphorus/carbon ratio in the suspension. This suggested a preferred adsorption of phosphorus‐containing EPS constituents to goethite and in turn to a compositional fractionation of EPS constituents between the solid and liquid phase as shown by Fourier‐transform infrared spectroscopy with attenuated total reflection (FTIR–ATR). Laser light diffraction measurements revealed a shift from the fine silt fraction to that of the fine sand that also supports the role of EPS as a ‘binding’ agent. Highlights Composite building units (CBUs) form in suspensions with different mineral and organic components. Both, hetero mineral–mineral and organo–mineral CBUs were formed. The initial composition of the suspension controls type and properties of resulting CBUs. Depending on the mineral surfaces, EPS may serve as a separation or binding agent.

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“…Finally, neutral conditions stand for pH of the solution equal to pH zpc . Extensive surveys reporting the pH zpc values for most used metal oxides and other semiconductors can be found in the literature review [154,155].…”

Section: Ph Of the Solutionmentioning

confidence: 99%

Hydrogen Generation through Solar Photocatalytic Processes: A Review of the Configuration and the Properties of Effective Metal-Based Semiconductor Nanomaterials

et al. 2017

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Photocatalytic water splitting and organic reforming based on nano-sized composites are gaining increasing interest due to the possibility of generating hydrogen by employing solar energy with low environmental impact. Although great efforts in developing materials ensuring high specific photoactivity have been recently recorded in the literature survey, the solar-to-hydrogen energy conversion efficiencies are currently still far from meeting the minimum requirements for real solar applications. This review aims at reporting the most significant results recently collected in the field of hydrogen generation through photocatalytic water splitting and organic reforming, with specific focus on metal-based semiconductor nanomaterials (e.g., metal oxides, metal (oxy)nitrides and metal (oxy)sulfides) used as photocatalysts under UVA or visible light irradiation. Recent developments for improving the photoefficiency for hydrogen generation of most used metal-based composites are pointed out. The main synthesis and operating variables affecting photocatalytic water splitting and organic reforming over metal-based nanocomposites are critically evaluated.

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Isoelectric points and points of zero charge of metal (hydr)oxides: 50years after Parks' review

Cited by 412 publications

References 599 publications

Optimized Nickel-Cobalt and Nickel-Iron Oxide Catalysts for the Hydrogen Evolution Reaction in Alkaline Water Electrolysis

Optimized Nickel-Cobalt and Nickel-Iron Oxide Catalysts for the Hydrogen Evolution Reaction in Alkaline Water Electrolysis

Formation of mineral–mineral and organo–mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances

Hydrogen Generation through Solar Photocatalytic Processes: A Review of the Configuration and the Properties of Effective Metal-Based Semiconductor Nanomaterials

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