The use of the pH at the point of zero charge for characterizing the properties of oxide hydroxides

Pechenyuk, S. I.

doi:10.1007/bf02495994

Cited by 36 publications

(22 citation statements)

References 33 publications

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“…depending on the surface's pH of zero charge (pHpzc). 99,100 At pH values higher than the pHpzc, negatively charged species accumulate on the surface (e.g. OH*, OOH*, O*, etc.).…”

Section: Proposed Reaction Mechanisms On Oxide Surfacesmentioning

confidence: 99%

Toward the rational design of non-precious transition metal oxides for oxygen electrocatalysis

Hong

Risch

Stoerzinger

et al. 2015

Energy Environ. Sci.

1,779

1,491

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REVIEWThis journal is © The Royal Society of Chemistry 2013 J. Name., 2013, 00, 1-3 | 1 In this Review, we discuss the state-of-the-art understanding of non-precious transition metal oxides that catalyze the oxygen reduction and evolution reactions. Understanding and mastering the kinetics of oxygen electrocatalysis is instrumental to making use of photosynthesis, advancing solar fuels, fuel cells, electrolyzers, and metal-air batteries. We first present key insights, assumptions and limitations of well-known activity descriptors and reaction mechanisms in the past four decades. The turnover frequency of crystalline oxides as promising catalysts is also put into perspective with amorphous oxides and photosystem II. Particular attention is paid to electronic structure parameters that can potentially govern the adsorbate binding strength and thus provide simple rationales and design principles to predict new catalyst chemistries with enhanced activity. We share new perspective synthesizing mechanism and electronic descriptors developed from both molecular orbital and solid state band structure principles. We conclude with an outlook on the opportunities in future research within this rapidly developing field. Broader ContextThe formation of chemical bonds is an energy dense mode of storing energy. In both nature and technology, the electrochemical generation and consumption of fuels is one of the most efficient routes for energy usage. Solar and electrical energy can be stored in chemical bonds by splitting water or metal oxides to produce hydrogen and metal. These compounds can then be oxidized to produce energy when coupled to the reduction of oxygen. However, these device efficiencies are severely limited by the catalysis of oxygen electrochemical processes -namely the oxygen reduction reaction and oxygen evolution reaction, which have slow kinetics. Non-precious transition metal oxides show promise as cost-effective substitutes for noble metals in commercially viable renewable energy storage and conversion devices. Furthermore, this class of materials has ben efitted from a wealth of spectroscopic and first-principles studies in the past few decades, providing the frameworks and theories needed to understand the electronic structure and design optimal catalysts. The incredibly diverse range of chemistries and physical properties that can be explored in oxide families afford numerous degrees of freedom for conducting systematic investigations relating intrinsic mat erial properties to catalytic performance. Here, we present background on the fundamental concepts in catalysis for the rational design of transition metal perovskite oxide catalysts for oxygen electrocatalysis and critically examine the current understanding a nd its impact on future directions of perovskite catalysts.

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“…depending on the surface's pH of zero charge (pHpzc). 99,100 At pH values higher than the pHpzc, negatively charged species accumulate on the surface (e.g. OH*, OOH*, O*, etc.).…”

Section: Proposed Reaction Mechanisms On Oxide Surfacesmentioning

confidence: 99%

Toward the rational design of non-precious transition metal oxides for oxygen electrocatalysis

Hong

Risch

Stoerzinger

et al. 2015

Energy Environ. Sci.

1,779

1,491

View full text Add to dashboard Cite

show abstract

“…The presence of impurities associated with the structure and configuration of surface charging is known to influence the point of zero charge possessed by an oxide/hydroxide (Pechenyuk, 1999). Theoretically, cation impurities in an iron oxide would be predicted to lower the pH pzc , yet Mayer Ranch does not follow this logic.…”

Section: Point Of Zero Chargementioning

confidence: 97%

“…The method of static points is particularly useful for the analysis of dry oxide powders, in that it makes the equal mass addition of iron to various solutions (of equal volume and different pH) both more convenient and more precise than the addition of amorphous gels (Pechenyuk, 1999).…”

Section: Point Of Zero Chargementioning

confidence: 99%

Potential Anionic Sorbent Use of Iron Oxides from Abandoned Mine Drainage Discharges

Neely¹,

Nairn²

2011

ASMR

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Abstract. This study examines the potential to reuse mine-drainage derived iron oxides as anionic sorbents for sustainable water treatment purposes. Pure iron oxides have been established as effective sorptive media or coatings for water treatment processes; yet, iron oxides from mine drainages remain to be an abundant but unproven source of this raw material. Iron oxides from both passive mine drainage treatment systems as well as environmental discharges of mine water and their associated iron deposits were examined. Based on prior physical characterization, three samples were selected (according to their specific surface area) to evaluate their anionic sorptive capacities pertaining to naturally occurring concentrations of orthophosphate (1.13 ± 0.03 mg/L) in surface waters, and arsenate (117.79 ± 4.08 µg As/L ) in drinking waters. The mine drainage derived iron oxides' performances were compared against a commercial grade iron oxide product, Bayoxide E33 P at static pH values of 6.00, 7.00, 8.00, and 9.00 ± 0.10 standard pH units via laboratory scale sorption batch experiments. As a result of these experiments it was observed that the mine drainage derived iron oxides were more effective at contaminant removal than the commercial product. Promising contaminant removal efficiencies of up to 95% (arsenate) and 99% (orthophosphate) were documented at specific pH values for the mine drainage derived iron oxides, while adhering to virtually all US EPA primary and secondary drinking water standards; thus suggesting that it may be feasible to beneficially reuse mine drainage derived iron oxide in water treatment technologies.

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“…Neely and Nairn (2011) describe iron oxides as prime candidates for mixed media filtration applications because of their large specific surface area and high affinity to form surface complexes with dissolved cations and anions (dependent upon the pH point of zero charge). When the pH of the ambient solution is above the pH pzc of the iron oxide, the surface charge is negative and cation removal is favored (e.g., Ahmed and Maksimov 1968, Pechenyuk 1999, Dzombak and Morel 1990, Kairies et al 2005. In the passive treatment of iron-rich mine water discharges containing elevated concentrations of ecotoxic trace metals, aerobic retention of Fe may result in significant trace metal removal via sorption and surface complexation.…”

Section: Introductionmentioning

confidence: 99%

Iron and Trace Metal Retention in Net Alkaline Co2-Rich Mine Waters via Aerobic Processes

Nairn¹,

LaBar²

2011

JASMR

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Aerobic iron removal is a well-documented treatment process for netalkaline mine waters. In this study, on-site field mesocosm experiments were conducted to evaluate effective oxidative removal of iron and trace metals from a lead-zinc mine discharge in the former were conducted in 40-L containers and water quality was analyzed over 24 hours to evaluate the effects of aeration and degassing on homogeneous and heterogeneous iron removal mechanisms. All treatments were established in triplicate. Iron concentrations decreased rapidly and significantly in the aerated treatments (180 mg/L to < 10 mg/L), with the addition of iron precipitate to the initial treatment having no significant impact on rates or final concentration. Iron concentrations also decreased significantly in the open buckets, but not as greatly (to ~170 mg/L), and decreased slightly (but not significantly) in the closed treatments (to ~190 mg/L).Zinc, nickel, arsenic, cadmium and lead concentrations also decreased significantly in the aerated treatments. Despite the production of proton acidity from iron hydrolysis, pH increased significantly in the aerated treatments (from ~6 to ~8) and slightly in the open treatments (~6 to ~6.1). The pH did not change in the closed treatments. Increased pH with increased iron removal indicates the major importance of CO 2 degassing by aeration, thus impacting both iron and trace metal concentration changes.

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The use of the pH at the point of zero charge for characterizing the properties of oxide hydroxides

Cited by 36 publications

References 33 publications

Toward the rational design of non-precious transition metal oxides for oxygen electrocatalysis

Toward the rational design of non-precious transition metal oxides for oxygen electrocatalysis

Potential Anionic Sorbent Use of Iron Oxides from Abandoned Mine Drainage Discharges

Iron and Trace Metal Retention in Net Alkaline Co2-Rich Mine Waters via Aerobic Processes

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