Fuel and oxygen harvesting from Martian regolithic brine

Gayen, Pralay; Sankarasubramanian, Shrihari; Ramani, Vijay

doi:10.1073/pnas.2008613117

Cited by 21 publications

(26 citation statements)

References 42 publications

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“…However, the oxidizing power of ClO 4 – is primarily utilized via rocket fuels, munitions, or pyrotechnics . Without ignition, ClO 4 – is a well-known inert anion and commonly used for ionic strength adjustment in various chemical systems . Abiotic reduction of aqueous ClO 4 – usually requires harsh conditions and large excesses of reducing agents. , Herein, we report on a bioinspired heterogeneous Mo catalyst for aqueous ClO 4 – reduction with 1 atm of H 2 at room temperature.…”

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confidence: 99%

A Bioinspired Molybdenum Catalyst for Aqueous Perchlorate Reduction

et al. 2021

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The detection of perchlorate (ClO4 − ) on and beyond Earth requires ClO4 − reduction technologies to support water purification and space exploration. However, the reduction of ClO4 − usually entails either harsh conditions or multi-component enzymatic processes. We developed a heterogeneous Mo−Pd/C catalyst from sodium molybdate to reduce aqueous ClO4 − into Cl − with 1 atm H2 at room temperature. Upon hydrogenation by H2/Pd, the reduced Mo oxide species and a bidentate nitrogen ligand (1:1 molar ratio) are transformed in situ into oligomeric Mo sites on the carbon support. The turnover number and frequency for oxygen atom transfer from ClOx − substrates reached 3850 and 165 h −1 on each Mo site. This simple bioinspired design yielded a robust water-compatible catalyst for the removal and utilization of ClO4 − .

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confidence: 99%

A Bioinspired Molybdenum Catalyst for Aqueous Perchlorate Reduction

et al. 2021

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“…Sci . 2020 , 117, 31685 . In this work, we demonstrated the efficacy of Pb 2 Ru 2 O 7‑ x as an anode electrocatalyst in Martian regolithic brine at a temperature of approximately −36 °C.…”

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confidence: 80%

“…An electrolyzer with Pb 2 Ru 2 O 7‑ x as the anode and Pt/C as the cathode was found to show record performance under room temperature alkaline seawater conditions (Figure d) . When Pb 2 Ru 2 O 7‑ x was used an the anode in a perchlorate brine electrolyzer under simulated Martian surface conditions, it exhibited a more than 25-times greater oxygen production rate than the Mars oxygen in situ resource utilization experiment from NASA’s Mars 2020 mission with the same input power, signifying the utility of pyrochlore anodes for future space applications (Figure e,f) …”

Section: Oxygen Electrocatalysismentioning

confidence: 99%

Pyrochlores for Advanced Oxygen Electrocatalysis

2022

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Metrics & MoreArticle Recommendations * sı Supporting Information CONSPECTUS: Fuel cells (FCs), water electrolyzers (WEs), unitized regenerative fuel cells (URFCs), and metal-air batteries (MABs) are among the emerging electrochemical technologies for energy storage, fuel (H 2 ), oxidant (O 2 ), and clean energy production.Their commercial applications are hindered by the low oxygen reduction reaction/ oxygen evolution reaction (ORR/OER) bifunctional activity (for URFCs and MABs), OER selectivity (brine electrolysis in seawater and Martian environments), and high cost of the benchmark electrocatalysts (OER: RuO 2 , IrO 2 and ORR: Pt/C) which affects the performance and affordability of the devices. Low-cost electrocatalysts with highly symmetric ORR/OER bifunctional activity and high OER selectivity are crucial for largescale FC, WE, URFC, and MAB application. Recent studies have revealed that tuning the structure of pyrochlore oxides provides a pathway to enhancing OER and ORR activity over a wide range of pH. Pyrochlore oxides commonly contain a cubic A 2 B 2 O 7-x structure with two types of tetrahedrally coordinated O atoms containing (1) A-O-A and (2) A-O-B types with a cationic radii mismatch of r A /r B > 1.5 and propensity toward oxygen vacancy formation. The variety of pyrochlore oxides and their tunable properties make them attractive for a wide spectrum of applications. Among all the metal oxides, Ru-based pyrochlores (e.g., Pb 2 Ru 2 O 7-x ) exhibit the best bifunctional oxygen electrocatalytic activity, i.e., low bifunctionality index (BI), in alkaline medium. Furthermore, pyrochlores exhibit high OER selectivity in brine electrolytes due to the presence of surface oxygen vacancies, making them suitable for space applications (brine electrolysis on Mars) and coastal hydrogen generation. Their bifunctional activity and selectivity can be further amplified by (1) substituting "A" and "B" sites of pyrochlores (AA′BB′O 7-x ), (2) tuning metal oxidation states of A and B by varying synthesis conditions, and (3) modulating oxygen vacancy concentration, each of which yield favorable structural and electronic variations. In recent years, research on the synthesis and understanding of pyrochlores has significantly enhanced their viability, offering a new horizon in the quest for economical and active electrocatalysts. However, an account that focuses on critical developments in this field is still lacking.In this Account, we focus on the recent development of a variety of pyrochlore electrocatalysts to understand intrinsic structureactivity-selectivity-stability relationships in these materials. Recent developments and applications of pyrochlore-based electrocatalysts are discussed under the following headings: (1) modulation of crystal and electronic structure of pyrochlores, (2) structure−activity−stability relationships of different pyrochlores for OER and ORR, (3) development of OER-selective pyrochlores for brine electrolysis, and (4) the application of pyrochlores in electrochemical devices. Finally, we...

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“…This time last year, it managed to wring out 5.37 g of O 2 for the first time on Mars; only enough to sustain ∼10 min worth of an astronaut's pedestrian activity, yet proof‐of‐concept support for the technology. Now there is a race on to improve O 2 extraction efficiency, not only from the atmosphere but also from ice and rock through the tweaking of electrocatalysts including perchlorate brine electrolysis of Martian regolith (Gayen et al., 2020) and alternative approaches focused on ‘plasma’‐driven electro‐ and photocatalytic technologies.…”

Section: Figurementioning

confidence: 99%

Oxygen: Making molecules for a mission to the Moon and Mars

Reichelt

2022

Experimental Physiology

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We humans can literally thank our lucky stars for those heavier elements needed to create DNA, specifically carbon, hydrogen, nitrogen, oxygen, phosphorous and sulphur (CHNOPS), forged inside the nuclear furnaces of dying stars that implode leaving behind supernova remnants (Bailey, 2020). Since the first cosmic whiff and most distant detection of O jettisoned by the galaxy MACS1149-JD1 ∼13.28 billion years ago at a time when the universe was <2% of its current age (Hashimoto et al., 2018), this element has become synonymous with life. With the advent of oxygenic photosynthesis, atmospheric levels of the diatomic oxygen (O 2 ) molecule (two Os glued together with a double covalent bond sharing two pairs of valence electrons) increased rapidly during the Proterozoic aeon of the Precambrian period, with each O 2 'pulse' sparking an explosion in Earth's biota, heralding the emergence of complex multicellular life, aerobic respiration and cephalisation. Indeed, the human brain stands as clear testament to our reliance on this precious gas and inherent vulnerability to failure when supply is cut off, given its voracious appetite in the face of little to no O 2 /glycogen reserves (Bailey, 2019). In short, we are all 'obligate neurobes'! But do not take this gas for granted, because atmospheric O 2 levels have started to wax and wane from the 20.93% (ambient P O 2 of 150 mmHg) that we have come to enjoy over the last ∼100 million years or so (Berner et al., 2007). Indeed, conservative estimates based on parabolic modelling (Livina et al., 2015) predict that within ∼3,600 years, living at sea level will feel as uncomfortably hypoxic as if we were atop a ∼5,340 m mountain, equivalent to the highest habitable elevation that humans can 'endure' here on Earth (Bailey, 2019). Complete depletion has been predicted to occur within ∼4.4 millennia, a sobering prospect that seems to have escaped public attention given current preoccupation with rising levels of that other gas, carbon dioxide (CO 2 ), the flipside of the climate coin. Hence the need to consider alternative sources of O 2 is important if we are to continue to sustain life here on Earth, or indeed beyond. This challenge has taken on new significance as humans plan extended missions to the lunar surface and beyond, with a crewed mission to Mars anticipated as early as the 2030s; the next frontier in our quest to becoming a spacefaring, multiplanetary species. Of all the planets in the solar system, Mars most closely resembles Earth, yet the journey to and habitation on the Red Planet pose unique physiological challenges. Astronauts will have to cope with the combined stresses of space radiation, altered gravity, isolation/confinement and closed environments (Patel et al., 2020) for 1,000 days on a planet located anywhere from ∼55 to 400 million km from Earth (dependent on the

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Fuel and oxygen harvesting from Martian regolithic brine

Cited by 21 publications

References 42 publications

A Bioinspired Molybdenum Catalyst for Aqueous Perchlorate Reduction

A Bioinspired Molybdenum Catalyst for Aqueous Perchlorate Reduction

Pyrochlores for Advanced Oxygen Electrocatalysis

Oxygen: Making molecules for a mission to the Moon and Mars

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