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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Myosin heavy chain expression in rodent skeletal muscle: effects of exposure to zero gravity

This study ascertained the effects of 9 days of zero gravity on the relative (percentage of total) and calculated absolute (mg/muscle) content of isomyosin expressed in both antigravity and locomotor skeletal muscle of ground control (CON) and flight-exposed (FL) rats. Results showed that although there were no differences in body weight between FL and CON animals, a significant reduction in muscle mass occurred in the vastus intermedius (VI) (P < 0.05) but not in the vastus lateralis (VL) or the tibialis anterior. Both total muscle protein and myofibril protein content were not different between the muscle regions examined in the FL and CON groups. In the VI, there were trends for reductions in the relative content of type I and IIa myosin heavy chains (MHCs) that were offset by increases in the relative content of both type IIb and possibly type IIx MHC protein (P > 0.05). mRNA levels were consistent with this pattern (P < 0.05). The same pattern held true for the red region of the VL as examined at both the protein and mRNA level (P < 0.05). When the atrophy process was examined, there were net reductions in the absolute content of both type I and IIa MHCs that were offset by calculated increases in type IIb MHC in both VI and red VL. Collectively, these findings suggest that there are both absolute and relative changes occurring in MHC expression in the "red" regions of antigravity skeletal muscle during exposure to zero gravity that could affect muscle function.

short duration↗
NASA NTRS1992

Collagen cross-linking of skin in patients with amyotrophic lateral sclerosis

Collagen cross-links of skin tissue (left upper arm) from 11 patients with amyotrophic lateral sclerosis (ALS) and 9 age-matched control subjects were quantified. It was found that patients with ALS had a significant reduction in the content of an age-related, stable cross-link, histidinohydroxylysinonorleucine, that was negatively correlated with the duration of illness. The contents of sodium borohydride-reducible labile cross-links, dehydro-hydroxylysinonorleucine and dehydro-histidinohydroxymerodesmosine, were significantly increased and were positively associated with the duration of illness (r = 0.703, p less than 0.05 and r = 0.684, p less than 0.05, respectively). The results clearly indicate that during the course of ALS, the cross-linking pathway of skin collagen runs counter to its normal aging, resulting in a "rejuvenation" phenomenon of skin collagen. Thus, cross-linking of skin collagen is affected in ALS.

Non-NASA Center↗
DOE OSTI2024

Surface chlorination of IrO2(110) by HCl

The ability to controllably chlorinate metal-oxide surfaces can provide opportunities for designing selective oxidation catalysts. In the present study, we investigated the surface chlorination of IrO2(110) by HCl using temperature programmed reaction spectroscopy (TPRS), x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. We find that exposing IrO2(110) to HCl, followed by heating to 650 K in ultrahigh vacuum, produces nearly equal quantities of on-top and bridging Cl atoms on the surface, Clt and Clbr, where the Clbr atoms replace O-atoms that are removed from the surface by H2O formation. After HCl adsorption at 85 K, only H2O desorbs at low Cl coverages during TPRS, but HCl begins to desorb in increasing yields as the Cl coverage is increased above about 0.5 monolayer (ML). The desorption of Cl2 was not observed under any conditions, in good agreement with the high barrier for this reaction predicted by DFT. A maximum Cl coverage of 1 ML, with nearly equal coverages of Clt and Clbr atoms, could be generated by reacting HCl with IrO2(110) in UHV. Our results suggest that a kinetic competition between recombinative HCl and H2O desorption under the conditions studied limits the saturation Cl coverage to a value less than the 2 ML maximum predicted by thermodynamics. XPS further shows that the partitioning of Cl between the Clt and Clbr states can be altered by subjecting partially chlorinated IrO2(110) to reductive or oxidative treatments, demonstrating that the Cl site population can change dynamically in response to the gas environment. Our results provide insights for understanding the chlorination of IrO2(110) by HCl and can enable future experimental studies to determine how Cl-modification alters the surface chemical reactivity of IrO2(110) and potentially enhances selectivity toward partial oxidation chemistry.

Chemistry↗
DOE OSTI2023

Electrically enhanced thermochemical cycles for hydrogen generation

In two-step metal-oxide (MO) solar thermochemical cycles, high temperature solar thermal energy is first converted to chemical energy in the form of a reduced MO. The reduced MO is then reoxidized in a second step with steam (or carbon dioxide) to produce hydrogen (or carbon monoxide) at a lower temperature. Solar thermochemical cycles of this type circumvent heat-to-electrical conversion required for electrochemical water splitting and promise high efficiencies. However, significant challenges remain to implementation. Ultra-high temperatures and efficiency-sapping low per-cycle conversion stand out as particularly difficult hurdles. Hybrid approaches utilizing both thermal and electrical energy provide some of the advantages of each, and can facilitate lower temperature operation and offer better per-pass utilization than thermochemical alone. However, early concepts for implementing the thermo-electrochemical approach introduced substantial new challenges including difficult separations, corrosive environments, and energy losses from large temperature swings and phase changes. We are currently investigating two different options for implementation. In the first, a MO that reduces at lower temperature is selected. As the reduced MO lacks the full thermodynamic driving force to effectively split water, the reaction is driven forward by an electrically-assisted proton-conducting membrane that separates and recovers hydrogen as it is produced. This approach produces a pure hydrogen stream, is mechanically simple, and has unique thermodynamic advantages. The second option seeks to more directly couple the electrical boost to the solid MO to drive either the reduction or oxidation step, or both, through the utilization of layered MO materials and advanced reactors. This approach could be applied to both water and carbon dioxide splitting. The results of process modeling and optimization will be presented, and progress towards demonstrating the concepts at the laboratory scale will be discussed.

08 HYDROGEN↗
DOE OSTI2025

Identifying microbial functional guilds performing cryptic organotrophic and lithotrophic redox cycles in anaerobic granular biofilms

Granular biofilms used in anaerobic digester systems contain diverse microbial populations that interact to hydrolyze organic matter and produce methane within controlled environments. Prior research investigated the feasibility of utilizing granular biofilms obtained from an anaerobic digester to remove nitrate without the addition of exogenous electron donors. These granules possessed a unique structure of alternating light and dark iron sulfide and pyrite rich layers that potentially served as both an electron source and sink, linking carbon, nitrogen, sulfur, and iron cycles. To characterize the functional roles of diverse microbial populations enriched within these layered biofilms, we analyzed metagenomes obtained from three different granules. Comparisons between the functional gene content of forty metagenome assembled genomes (MAGs) identified phylogenetically cohesive functional guilds. Each of these functional MAG clusters was assigned to specific steps in anaerobic digestion (hydrolysis, acidogenesis, acetogenesis, and methanogenesis) and anaerobic respiration (denitrification and sulfate reduction). Comparisons with metagenomes derived from a variety of natural and engineered ecosystems confirmed that the enriched denitrifying bacteria were similar to populations typically found in wetlands and biological nitrogen removal systems. Analysis of read alignments to individual genes within the forty MAGs identified conserved genomic features that were representative of the functions that distinguished functional guilds. Overall, this research illustrates the utility of functional based classification of microorganisms for characterizing ecosystem functions and highlights the potential application of engineered ecosystems to serve as experimental models for complex natural ecosystems.

Ecosystem engineering↗
DOE OSTI2024

Interactive effects of salinity, redox, and colloids on greenhouse gas production and carbon mobility in coastal wetland soils

Coastal wetlands, including freshwater systems near large lakes, rapidly bury carbon, but less is known about how they transport carbon either to marine and lake environments or to the atmosphere as greenhouse gases (GHGs) such as carbon dioxide and methane. This study examines how GHG production and organic matter (OM) mobility in coastal wetland soils vary with the availability of oxygen and other terminal electron acceptors. We also evaluated how OM and redox-sensitive species varied across different size fractions: particulates (0.45–1μm), fine colloids (0.1–0.45μm), and nano particulates plus truly soluble (<0.1μm; NP+S) during 21-day aerobic and anaerobic slurry incubations. Soils were collected from the center of a freshwater coastal wetland (FW-C) in Lake Erie, the upland-wetland edge of the same wetland (FW-E), and the center of a saline coastal wetland (SW-C) in the Pacific Northwest, USA. Anaerobic methane production for FW-E soils were 47 and 27,537 times greater than FW-C and SW-C soils, respectively. High Fe 2+ and dissolved sulfate concentrations in FW-C and SW-C soils suggest that iron and/or sulfate reduction inhibited methanogenesis. Aerobic CO 2 production was highest for both freshwater soils, which had a higher proportion of OM in the NP+S fraction (64±28% and 70±10% for FW-C and FW-E, respectively) and organic C:N ratios reflective of microbial detritus (5.3±5.3 and 5.3±7.0 for FW-E and FW-C, respectively) compared to SW-C, which had a higher fraction of particulate (58±9%) and fine colloidal (19±7%) OM and organic C:N ratios reflective of vegetation detritus (11.4 ± 1.7). The variability in GHG production and shifts in OM size fractionation and composition observed across freshwater and saline soils collected within individual and across different sites reinforce the high spatial variability in the processes controlling OM stability, mobility, and bioavailability in coastal wetland soils.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1998

Shewanella amazonensis sp. nov., a novel metal-reducing facultative anaerobe from Amazonian shelf muds

A new bacterial species belonging to the genus Shewanella is described on the basis of phenotypic characterization and sequence analysis of its 16S rRNA-encoding and gyrase B (gyrB) genes. This organism, isolated from shallow-water marine sediments derived from the Amazon River delta, is a Gram-negative, motile, polarly flagellated, facultatively anaerobic, rod-shaped eubacterium and has a G&C content of 51.7 mol%. Strain SB2BT is exceptionally active in the anaerobic reduction of iron, manganese and sulfur compounds. SB2BT grows optimally at 35 degrees C, with 1-3% NaCl and over a pH range of 7-8. Analysis of the 16S rDNA sequence revealed a clear affiliation between strain SB2BT and members of the gamma subclass of the class Proteobacteria. High similarity values were found with certain members of the genus Shewanella, especially with Shewanella putrefaciens, and this was supported by cellular fatty acid profiles and phenotypic characterization. DNA-DNA hybridization between strain SB2BT and its phylogenetically closest relatives revealed low similarity values (24.6-42.7%) which indicated species status for strain SB2BT. That SB2BT represents a distinct bacterial species within the genus Shewanella is also supported by gyrB sequence analysis. Considering the source of the isolate, the name Shewanella amazonensis sp. nov. is proposed and strain SB2BT (= ATCC 700329T) is designated as the type strain.

NASA Discipline Exobiology↗
DOE OSTI2022

Vapor–Fed Electrolyzers for Carbon Dioxide Reduction Using Tandem Electrocatalysts: Cuprous Oxide Coupled with Nickel–Coordinated Nitrogen–Doped Carbon

We report ethylene is particularly attractive due to its major importance as a feedstock for various applications including the polymer industry. As such, catalyst and electrolyzer developments are crucial to achieve industrially relevant ethylene production and efficiency levels. In this work, a tandem electrocatalyst composed of copper nanocubes and nickel-coordinated nitrogen-doped carbon (NiNC) is presented, which is integrated into gas diffusion electrodes (GDEs) for direct conversion of vapor-fed CO 2 into ethylene. Evaluation of tandem GDEs in the vapor-fed flow electrolyzer shows significantly increased ethylene selectivity in terms of faradaic efficiency and C 2 H 4 /CO ratio compared to a non-tandem copper GDE. The enhancements are attributed to the increased local CO availability near the copper surface via effective CO 2 to CO conversion on neighboring NiNC. The experimental results are validated by 3D resolved continuum simulations, which show increased flux of higher-order prod-ucts with the added CO flux from NiNC. The practical viability of Cu/NiNC catalyst is further evaluated in a membrane electrode assembly electrolyzer, achieving 40% FE toward ethylene at 150 mA cm -2 and 3.2 V. These find-ings highlight the high selectivity and formation rate of ethylene achieved by successful device integration of the Cu/NiNC catalyst, demonstrating the potential for implementation in large-scale sustainable CO 2 electrolyzers.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The unique Phe–His dyad of 2-ketopropyl coenzyme M oxidoreductase/carboxylase selectively promotes carboxylation and S–C bond cleavage

The 2-ketopropyl-coenzyme M oxidoreductase/carboxylase (2-KPCC) enzyme is the only member of the disulfide oxidoreductase (DSOR) family of enzymes, which are important for reductively cleaving S–S bonds, to have carboxylation activity. 2-KPCC catalyzes the conversion of 2-ketopropyl-coenzyme M to acetoacetate, which is used as a carbon source, in a controlled reaction to exclude protons. A conserved His–Glu motif present in DSORs is key in the protonation step; however, in 2-KPCC, the dyad is substituted by Phe–His. Here, we propose that this difference is important for coupling carboxylation with C–S bond cleavage. We substituted the Phe–His dyad in 2-KPCC to be more DSOR like, replacing the phenylalanine with histidine (F501H) and the histidine with glutamate (H506E), and solved crystal structures of F501H and the double variant F501H_H506E. We found that F501 protects the enolacetone intermediate from protons and that the F501H variant strongly promotes protonation. We also provided evidence for the involvement of the H506 residue in stabilizing the developing charge during the formation of acetoacetate, which acts as a product inhibitor in the WT but not the H506E variant enzymes. Finally, we determined that the F501H substitution promotes a DSOR-like charge transfer interaction with flavin adenine dinucleotide, eliminating the need for cysteine as an internal base. Taken together, these results indicate that the 2-KPCC dyad is responsible for selectively promoting carboxylation and inhibiting protonation in the formation of acetoacetate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Constructing Highly Durable Fuel Cell Catalysts Through Integrating Graphitic Shell‐Protected Composite Carbon Support with Gaseous Co Deposition‐Driven PtCo Intermetallics

Metal dissolution, nanoparticle agglomeration, and carbon support corrosion cause significant performance degradation of current PtCo catalysts under acidic and oxidative oxygen reduction reaction. Here, in this study, an integrated strategy is presented to design high-performance Pt 3 Co intermetallic catalysts by regulating gaseous Co deposition-driven diffusion into Pt nanoparticles supported on a composite carbon. The composite carbon is derived from ZIF-8/polyaniline, consisting of a high-surface-area (HSC) core and a protective graphitic shell (GS), which is employed to design 40 wt.% Pt/HSC@GS catalyst. The corresponding membrane electrode assemblies (MEAs) can maintain 1.09 A cm −2 at 0.7 V (20. 7% loss) after 10 000 cycles (1.0–1.5 V for carbon stability) and 1.15 A cm −2 (16.1% loss) after 150 000 cycles (0.60–0.95 V for catalyst stability). A ordered Pt 3 Co intermetallic is synthesized via a gaseous Co-deposition process, which yields a homogeneous Co-rich layer onto the Pt nanoparticles on the composite support, thereby facilitating Co diffusion into Pt crystal during subsequent ordering annealing to form the ordered intermetallic structure. This gaseous deposition leads to a thin carbon layer on PtCo nanoparticles, inhibiting particle growth during the annealing and mitigating Co dissolution under dynamic electrochemical conditions. The PtCo catalyst achieves impressive MEA performance and long-term durability (1.45 A cm −2 at 0.7 V after 120 000 cycles) under heavy-duty conditions.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Uncovering the Solvation Structure of LiPF 6 –Based Localized Saturated Electrolytes and Their Effect on LiNiO 2 –Based Lithium–Metal Batteries

Electrolytes play a critical role in stabilizing highly reactive lithium-metal anodes (LMAs) and high-voltage cathodes for rechargeable lithium-metal batteries (LMBs). Localized high concentration electrolytes (LHCEs) have achieved remarkable success in the context of LMBs. However, the state-of-the-art LHCEs are based on LiFSI salt, which is prohibitively expensive. Here, the utility of low-cost LiPF 6 salt in localized saturated electrolytes (LSEs) with a series of solvents and diluents in LMBs with cobalt-free LiNiO 2 cathode is systematically explored. Experimental and theoretical analyses reveal that the unique solvation structure formed not only changes the distribution of solvents and anions but also alters the atom–atom distances within them, leading to different reduction and oxidation stabilities compared to low-concentration electrolytes. In addition, LSEs help form LiF-rich interphase layers on the LMA and LiNiO 2 cathode, protecting the electrodes from degradation during cycling. Different LSEs also lead to differences in lithium plating morphology and impedance buildup during cycling, impacting the performance of LMBs. Finally, the solvent and diluent must be carefully selected for compatibility with a lithium salt when developing LHCEs and LSEs for LMBs.

25 ENERGY STORAGE↗
DOE OSTI2021

Ce IV 70 Oxosulfate Rings, Frameworks, Supramolecular Assembly, and Redox Activity**

Abstract M IV molecular oxo‐clusters (M=Zr, Hf, Ce, Th, U, Np, Pu) are prolific in bottoms‐up material design, catalysis, and elucidating reaction pathways in nature and in synthesis. Here we introduce Ce 70 , a wheel‐shaped oxo‐cluster, [Ce IV 70 (OH) 36 (O) 64 (SO 4 ) 60 (H 2 O) 10 ] 4− . Ce 70 crystallizes into intricate high pore volume frameworks with divalent transition metals and Ce‐monomer linkers. Eight crystal‐structures feature four framework types in which the Ce 70 ‐rings are linked as propellers, in offset‐stacks, in a tartan pattern, and as isolated rings. Small‐angle X‐ray scattering of Ce 70 dissolved in butylamine, with and without added cations (Ce IV , alkaline earths, Mn II ), shows the metals‘ differentiating roles in ring linking, leading to supramolecular assemblies. The large acidic pores and abundant terminal sulfates provide ion‐exchange behavior, demonstrated with U IV and Nd III . Frameworks featuring Ce III/IV ‐monomer linkers demonstrate both oxidation and reduction. This study opens the door to mixed‐metal, highly porous framework catalysts, and new clusters for metal‐organic framework design

Colliard, Ian↗
DOE OSTI2021

Ce IV 70 oxosulfate rings, frameworks, supramolecular assembly and redox activity

M IV molecular oxo-clusters (M=Zr, Hf, Ce, Th, U, Np, Pu) are prolific in bottoms-up material design, catalysis, and elucidating reaction pathways in nature and in synthesis. Here we introduce Ce 70 , a wheel-shaped oxo-cluster, [Ce IV 70 -(OH) 36 (O) 64 (SO 4 ) 60 (H 2 O) 10 ] 4- . Ce 70 crystallizes into intricate high pore volume frameworks with divalent transition metals and Ce-monomer linkers. Eight crystal-structures feature four framework types in which the Ce 70 -rings are linked as propellers, in offset-stacks, in a tartan pattern, and as isolated rings. In this work, small-angle X-ray scattering of Ce 70 dissolved in butylamine, with and without added cations (Ce IV , alkaline earths, Mn II ), shows the metals‘ differentiating roles in ring linking, leading to supramolecular assemblies. The large acidic pores and abundant terminal sulfates provide ion-exchange behavior, demonstrated with U IV and Nd III . Frameworks featuring Ce III/IV -monomer linkers demonstrate both oxidation and reduction. Furthermore, this study opens the door to mixed-metal, highly porous framework catalysts, and new clusters for metal-organic framework design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Electrochemical Lignin Conversion

Lignin is the largest source of renewable aromatic compounds, making the recovery of aromatic compounds from this material a significant scientific goal. Recently, many studies have reported on lignin depolymerization and upgrading strategies. Electrochemical approaches are considered to be low cost, reagent free, and environmentally friendly, and can be carried out under mild reaction conditions. Here, different electrochemical lignin conversion strategies, including electrooxidation, electroreduction, hybrid electro-oxidation and reduction, and combinations of electrochemical and other processes (e.g., biological, solar) for lignin depolymerization and upgrading are discussed in detail. In addition to lignin conversion, electrochemical lignin fractionation from biomass and black liquor is also briefly discussed. Finally, the outlook and challenges for electrochemical lignin conversion are presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Continuous assessment of metabolic activity of mitochondria using resonance Raman microspectroscopy

Dysfunctional mitochondrial activity can lead to a variety of different diseases. As such, there exists a need to quantify changes in mitochondria function as it relates to these specific diseased states. Here, we present the use of resonance Raman (RR) spectroscopy as a tool to determine changes in isolated mitochondrial activity. RR spectroscopy, using 532 nm as the excitation source, specifically provides information on the reduction and oxidation (RedOx) state of cytochrome c, which is determined by the activity of protein complexes in the electron transport chain. In this model, injection of the substrate succinate into the mitochondrial sample is used to drive the electron transport chain, which causes a subsequent change in cytochrome c RedOx state. This change in RedOx state is tracked by RR spectroscopy. We report this tool gives real-time information on the rise and fall of the amount of reduced cytochrome c within the mitochondrial sample, providing a method for rapid assessment of mitochondrial metabolism that has broad applications in both basic science and medical research.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Thiol redox proteomics: Characterization of thiol-based post-translational modifications

Redox post-translational modifications on cysteine thiols (redox PTMs) have profound effects on protein structure and function, thus enabling regulation of various biological processes. Redox proteomics approaches aim to characterize the landscape of redox PTMs at the systems level. These approaches facilitate studies of condition-specific, dynamic processes implicating redox PTMs and have furthered our understanding of redox signaling and regulation. Mass spectrometry (MS) is a powerful tool for such analyses which has been demonstrated by significant advances in redox proteomics during the last decade. A group of well-established approaches involves the initial blocking of free thiols followed by selective reduction of oxidized PTMs and subsequent enrichment for downstream detection. Alternatively, novel chemoselective probe-based approaches have been developed for various redox PTMs. Direct detection of redox PTMs without any enrichment has also been demonstrated given the sensitivity of contemporary MS instruments. This review discusses the general principles behind different analytical strategies and covers recent advances in redox proteomics. Several applications of redox proteomics are also highlighted to illustrate how large-scale redox proteomics data can lead to novel biological insights.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Photodepositing CdS on the Active Cyano Groups Decorated g‐C 3 N 4 in Z‐Scheme Manner Promotes Visible‐Light‐Driven Hydrogen Evolution

Abstract g‐C 3 N 4 /CdS heterojunctions are potential photocatalysts for hydrogen production but their traditional type‐II configuration generally leads to weak oxidative and reductive activity. How to construct the novel Z‐scheme g‐C 3 N 4 /CdS counterparts to address this issue remains a great challenge in this field. In this work, a new direct Z‐scheme heterojunction of defective g‐C 3 N 4 /CdS is designed by introducing cyano groups (NC‐) as the active bridge sites. Experimental observations in combination with density functional theory (DFT) calculations reveal that the unique electron‐withdrawing feature of cyano groups in the defective g‐C 3 N 4 /CdS heterostructure can endow this photocatalyst with numerous advantageous properties including high light absorption ability, strong redox performance, satisfactory charge separation efficiency, and long lifetime of charge carriers. Consequently, the resultant photocatalytic system exhibits more active performance than CdS and g‐C 3 N 4 under visible light and reaches an excellent hydrogen evolution rate of 1809.07 µmol h −1 g −1 , which is 6.09 times higher than pristine g‐C 3 N 4 . Moreover, the defective g‐C 3 N 4 /CdS photocatalyst maintains good stability after 40 h continuous test. This work provides new insights into design and construction of Z‐scheme heterojunctions for regulating the visible‐light‐induced photocatalytic activity for H 2 evolution.

Wang, Zhipeng↗
DOE OSTI2023

Redox‐Functionalized Semiconductor Interfaces for Photoelectrochemical Separations

Redox-mediated electrosorption is a promising platform for selective electrochemical (EC) separations, due to its molecular selectivity, high uptake, and tunability for target ions. However, the electrical energy required is mainly generated by non-renewable energy sources, which limits its sustainability and overall impact to decarbonization. Here, a redox-mediated photoelectrochemical (PEC) separation process using polyvinyl ferrocene functionalized TiO 2 nanorod electrodes is proposed, which integrates direct solar energy as a driver for the selective electrosorption. The photoelectrochemically-driven oxidation and reduction with both homogeneous and heterogeneous ferrocene-systems is investigated to establish the underlying mechanism. The PEC system can separate heavy metal oxyanions at lower voltages or even without electrical energy. At 0.3 V versus SCE, a 124 mg g −1 uptake for Mo is achieved, which is comparable to the performance of EC cells at 0.75 V versus SCE. Thus, PEC systems not only can generate energy for spontaneous redox-separations, but also can reduce electrical energy consumption by 51.4% compared to EC cells for separation processes when coupled with an external electrical energy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗