Weeks Of Continuous Operation Research Articles

High-Performance and Scalable Aqueous Na-Ion Batteries Comprising a Co-Prussian Blue Analogue Framework Positive Electrode and Sodium Vanadate Nanorod Negative Electrode for Solar Energy Storage

A unique configuration of aqueous Na-ion batteries is investigated for solar energy storage, where single-wall carbon nanotube (SWCNT)-coated stainless steel (SS304), Co-Prussian blue analogue (Co-PBA/Na2CoFe(CN)6), and sodium vanadate (NVO/NaV3O8) nanorods are employed as a current collector, positive active material, and negative active material, respectively. The SWCNT coverage on SS radically obstructs the metallic corrosion under anodic polarization and also enhances the electrolyte stability window by preventing direct contact between the metal substrate and electrolyte. Both the positive and negative materials are structurally analyzed by Rietveld refinement of powder X-ray diffraction data. The Co-PBA framework structure demonstrates one-dimensional channels with ∼5.3 and 5.1 Å widths along [100] and [011], respectively, whereas the layered NVO depicts an interlayer spacing of ∼4.2 Å for facile Na-ion transportations. Resultantly, the high diffusion coefficients of Na-ions in Co-PBA and NVO are achieved as 1.6 × 10–13 and 2.0 × 10–11 cm2 s–1, respectively. Both Co-PBA and NVO exhibit a diffusion-controlled Faradaic charge storage mechanism, which has been demonstrated by cyclic voltammetry. The Co-PBA provides 122 mAh g–1 specific capacity at 1C rate, which is the highest reported value in aqueous medium with low-cost current collectors. The electrochemical performance testing of NaV3O8 is first described by us, explicitly for the negative electrode, and it delivers 83 mAh g–1 specific capacity at 1C. The 1.5 V silica gel-based Co-PBA//NVO full cell is fabricated with mass balancing, which shows higher cell voltage by maximizing the water splitting window. The full cell delivers a specific capacity of 141 mAh g–1 (@ 1C), an energy density of 211 Wh kg–1 (@ 250 W kg–1), a power density of 2466 W kg–1 (@ 94 Wh kg–1), and good durability (80% capacity retention @ 5C) up to 500 cycles. A 3 V/5 mAh rated prototype device is assembled, and it delivers satisfactory solar energy storage performances under 1 week of continuous operation.

Single-Pass Tangential Flow Filtration (SPTFF) of Nanoparticles: Achieving Sustainable Operation with Dilute Colloidal Suspensions for Gene Therapy Applications.

Recent approval of several viral-vector-based therapeutics has led to renewed interest in the development of more efficient bioprocessing strategies for gene therapy products. Single-Pass Tangential Flow Filtration (SPTFF) can potentially provide inline concentration and final formulation of viral vectors with enhanced product quality due. In this study, SPTFF performance was evaluated using a suspension of 100 nm nanoparticles that mimics a typical lentivirus system. Data were obtained with flat-sheet cassettes having 300 kDa nominal molecular weight cutoff, either in full recirculation or single-pass mode. Flux-stepping experiments identified two critical fluxes, one based on boundary-layer particle accumulation (Jbl) and one based on membrane fouling (Jfoul). The critical fluxes were well-described using a modified concentration polarization model that captures the observed dependence on feed flow rate and feed concentration. Long-duration filtration experiments were conducted under stable SPTFF conditions, with the results suggesting that sustainable performance could potentially be achieved for as much as 6 weeks of continuous operation. These results provide important insights into the potential application of SPTFF for the concentration of viral vectors in the downstream processing of gene therapy agents.

Intraligand Charge Transfer Enables Visible-Light-Mediated Nickel-Catalyzed Cross-Coupling Reactions.

We demonstrate that several visible-light-mediated carbon-heteroatom cross-coupling reactions can be carried out using a photoactive NiII precatalyst that forms in situ from a nickel salt and a bipyridine ligand decorated with two carbazole groups (Ni(Czbpy)Cl2 ). The activation of this precatalyst towards cross-coupling reactions follows a hitherto undisclosed mechanism that is different from previously reported light-responsive nickel complexes that undergo metal-to-ligand charge transfer. Theoretical and spectroscopic investigations revealed that irradiation of Ni(Czbpy)Cl2 with visible light causes an initial intraligand charge transfer event that triggers productive catalysis. Ligand polymerization affords a porous, recyclable organic polymer for heterogeneous nickel catalysis of cross-coupling reactions. The heterogeneous catalyst shows stable performance in a packed-bed flow reactor during a week of continuous operation.

Intraligand Charge Transfer Enables Visible‐Light‐Mediated Nickel‐Catalyzed Cross‐Coupling Reactions**

AbstractWe demonstrate that several visible‐light‐mediated carbon−heteroatom cross‐coupling reactions can be carried out using a photoactive NiII precatalyst that forms in situ from a nickel salt and a bipyridine ligand decorated with two carbazole groups (Ni(Czbpy)Cl2). The activation of this precatalyst towards cross‐coupling reactions follows a hitherto undisclosed mechanism that is different from previously reported light‐responsive nickel complexes that undergo metal‐to‐ligand charge transfer. Theoretical and spectroscopic investigations revealed that irradiation of Ni(Czbpy)Cl2 with visible light causes an initial intraligand charge transfer event that triggers productive catalysis. Ligand polymerization affords a porous, recyclable organic polymer for heterogeneous nickel catalysis of cross‐coupling reactions. The heterogeneous catalyst shows stable performance in a packed‐bed flow reactor during a week of continuous operation.

Mixed perovskite (MAPbI3-xClx) solar cells using light-emitting conjugated polymer DMP end-capped MDMO-PPV as a hole transport material

A series of solar cells (SCs) with methylammonium mixed halide perovskite active layers with a conjugated polymer (CP) poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene] and end-capped with dimethylphenyl (MDMO-PPV) as a hole transport material (HTM) was fabricated under the same experimental settings, and the performance characteristics of the individual cells were compared. For comparison purposes, we fabricated a perovskite solar cell (PSC) with a lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI)-doped sprio-OMeTAD layer (LiTSO), which showed a power conversion efficiency (PCE) of 7.68 %. The layered solar cell with a structure of TiO2, perovskite and MDMO-PPV layers showed a PCE of 5.32 % and a fill factor of 0.478. The heterojunction solar cell (HJSC) made with a perovskite and MDMO-PPV mix showed a PCE of 5.68 %. The Field emission scanning electron microscope (FESEM) showed that in HJSC, the perovskite and CP were mixed well. However, they did not penetrate deeply into the TiO2 mesoporous layer, which would hinder electron transportation and thus cause efficiency loss. The HJSC structure was tested using different thicknesses of mesoporous TiO2 (m-TiO2). At an optimal m-TiO2 thickness, the blend of perovskite and MDMO-PPV infused up to 350 nm, thus improving the PCE to 7.438 % and retaining 91 % performance even after 4 weeks of continuous operation. The perovskite/conjugated polymer blend also formed a small SC above the m-TiO2 layer, showing complete penetration of the perovskite into the m-TiO2 layer. Additionally, the formation of a pure perovskite layer on top of the TiO2/perovskite and MDMO-PPV covers neatly on top of the perovskite layer and serves as a protective layer as well as a hole transport layer. An additional layer of LiTSO on top of the HJSC further improved the PCE to 7.76 %. The use of a CP as the hole transport layer reduces the dependency on separate materials and improves the device’s stability. It could also pave the way for an easy minimalistic method for integrated, flexible power electronics that contain solar cells (perovskite/conjugated polymer), organic light-emitting diodes, and supercapacitors made of graphene.

Automatically Controlled Dust Generation System Using Arduino.

A dust generator was developed to disperse and maintain a desired concentration of airborne dust in a controlled environment chamber to study poultry physiological response to sustained elevated levels of particulate matter. The goal was to maintain an indicated PM10 concentration of 50 µg/m3 of airborne dust in a 3.7 m × 4.3 m × 2.4 m (12 ft × 14 ft × 8 ft) controlled environment chamber. The chamber had a 1.5 m3/s (3200 cfm) filtered recirculation air handling system that regulated indoor temperature levels and a 0.06 m3/s (130 cfm) exhaust fan that exchanged indoor air for fresh outdoor air. Dry powdered red oak wood dust that passed through an 80-mesh screen cloth was used for the experiment. The dust generator metered dust from a rectangular feed hopper with a flat bottom belt to a 0.02 m3/s (46 cfm) centrifugal blower. A vibratory motor attached to the hopper ran only when the belt was operated to prevent bridging of powdered materials and to provide an even material feed rate. A laser particle counter was used to measure the concentration of airborne dust and provided feedback to an Arduino-based control system that operated the dust generator. The dust generator was operated using a duty cycle of one second on for every five seconds off to allow time for dispersed dust to mix with chamber air and reach the laser particle counter. The control system maintained an airborne PM10 dust concentration of 54.92 ± 6.42 µg/m3 in the controlled environment chamber during six weeks of continuous operation using red oak wood dust. An advantage of the automatically controlled dust generator was that it continued to operate to reach the setpoint concentration in response to changes in material flow due to humidity, partial blockages, and non-uniform composition of the material being dispersed. Challenges included dust being trapped by the recirculation filter and the exhaust fan removing airborne dust from the environmental chamber.

LaNiTiO3-SE-based stabilized zirconium oxide mixed potentiometric SO2 gas sensor

In this paper, a mixed potential gas sensor based on YSZ solid electrolyte and LaNiTiO3 sensing electrode was produced. The perovskite-type oxide LaNiTiO3 was synthesized by the sol-gel method as a sensitive electrode, which was intended to detect the low-level concentration of SO2 in the environment. After the aging process and continuous testing, it was found that the LaNiTiO3-SE sensor had the best response value of −27.5 mV to 5 ppm SO2 at 510 °C, at this temperature, as low as 50 ppb SO2 still had a response of -1mV. Meanwhile, when the sensor was tested at 510 °C, it was found that the response value of the sensor showed a piecewise linear relationship with the logarithm of SO2 concentration, with a sensitivity of -4 mV/decade for 0.05–1 ppm SO2 and -40mV/decade for 1–100 ppm SO2. In addition, the sensor also showed good selectivity, and the response to interference gases could be ignored such as NO2, CO, CH4, NH3, H2, ethanol, and formaldehyde. At the same time, the sensor also shows good repeatability and stability, being still relatively stable after two weeks of continuous operation at high-temperature.

Urea Biosensor Based on a CO2 Microsensor.

Urea sensors based on electrodes in direct contact with the medium have limited long-term stability when exposed to complex media. Here, we present a urea biosensor based on urease immobilized in an alginate polymer, buffered at pH 6, and placed in front of a newly developed fast and sensitive CO2 microsensor, where the electrodes are shielded by a gas-permeable membrane. The CO2 produced by the urease in the presence of urea diffuses into the microsensor and is reduced at a Ag cathode. Oxygen interference is prevented by a Cr2+ trap. The 95% response time to changes in urea concentration was 120 s with a linear calibration curve in the range 0–1000 μM and a detection limit of 1 μM. The Ni2+ cofactor to improve sensor performance was continuously supplied from a reservoir behind the sensor tip. The stability of the urea sensor was optimized by the addition of bovine serum albumin as a stabilizer to the urease/alginate mixture that was cross-linked with glutaraldehyde and Ca2+ ions. This immobilization strategy resulted in about 70% of the initial urea sensor sensitivity after two weeks of continuous operation. The sensor was successfully tested in blood serum.

Printed, cost-effective and stable poly(3-hexylthiophene) electrolyte-gated field-effect transistors

A large-area processable ink-jet-printed poly(3-hexylthiophene) electrolyte-gated field-effect transistor, designed for bioelectronic applications, is proven to be stable for one week of continuous operation.

Étude de la performance du milieu filtrant constitué d’une couche de chènevotte sur une couche de grignons d'olives dans le traitement des eaux usées domestiques : du pilote à l’échelle industrielle

Deux matériaux, sous-produits agro-industriels, ont été étudiés en biofiltration à l'échelle pilote : la chènevotte en tant que « couche active », sur des grignons d'olives en tant que « couche de support ». L'objectif était d'étudier la capacité de ces deux matériaux travaillant ensemble comme un seul milieu filtrant poreux. L'impact de la hauteur de la couche active sur la performance du biofiltre a été étudié expérimentalement grâce à deux biofiltres, un premier présentant une répartition des matériaux en deux hauteurs égales, l’autre avec 80 % de couche active sur 20 % de hauteur de couche support. Les deux pilotes ont été alimentés à raison de 75 L·j‑1·EH‑1 (EH : équivalent-habitant) avec des eaux usées domestiques synthétiques. Les résultats ont montré une réduction de la demande biochimique en oxygène en cinq jours (DBO5) et des matières en suspension (MES) de plus de 90 % après dix semaines de fonctionnement. Cette performance s'est maintenue après plus de 30 semaines de fonctionnement continu. Par ailleurs, six prototypes de biofiltres ont été installés pour traiter les eaux usées domestiques de résidences unifamiliales dans des conditions réelles. Les objectifs de cette étude sont de caractériser l'efficacité du traitement de ces prototypes sur plusieurs années dans des conditions réelles, de déterminer l'entretien requis par une telle technologie et d'étudier l'influence de paramètres tels que la hauteur du biofiltre, l'aération et le nombre d'habitants. L'efficacité de traitement à long terme de l'un des biofiltres, qui fonctionne depuis près de quatre ans, est remarquable. Les pourcentages moyens de réduction de la demande chimique en oxygène (DCO), de la DBO5 et de MES sont respectivement de plus de 83 %, 97 % et 96 %, laissant espérer des résultats prometteurs pour les cinq autres.

An Evaluation of Carbon and Mixed Metal Oxide Electrodes for High Voltage Redox Flow Batteries

Aqueous redox flow battery (RFB) technology is limited by relatively low energy and power densities; thus positive redox couples with higher thermodynamic potentials are of interest. However, higher voltage couples introduce additional complications related to electrode corrosion and the possibility of oxygen evolution as an un-wanted side reaction. In this effort, the stability and catalytic activity for typical carbon felt electrodes were determined for the positive reaction in common (Br-/Br2, V4+/5+) and higher voltage (Mn2+/3+, Ce3+/4+) RFB chemistries. Weight loss measurements were performed as a test of carbon oxidation and/or loss of material due to mechanical breakdown. In addition to baselining existing carbon electrodes, mixed metal oxide (MMO) electrodes provided by De Nora Tech were evaluated in similar tests to provide a comparison of performance. Carbon felt electrodes were tested in each electrolyte. The felt was Morgan Advanced Materials’ VDG grade, 1/8” (3.2 mm) nominal thickness. This is a ‘graphitic’ felt, which is produced by pyrolysis of a rayon precursor at 1900°C. The felts were heat treated before use to improve their wettability; the heat treatment consisted of being held at 400°C in air for 6 hours. For each redox couple the following electrochemical measurements were made: Polarization curves (initial, final and at intermediate times)AC impedance (initial, final and intermediate)Polarization at a fixed current density for at least one week of continuous operation (typically at 100 mA/cm2) in a symmetric cell arrangement where one electrode was continually performing the oxidation reaction, and one electrode was continually performing the reduction reaction) Each felt electrode was weighed prior to, and after, being tested. Oxygen evolution rates were estimated from the difference between polarization curves obtained with and without the redox couple in solution. Similar measurements were made with six different MMO formulations which were deposited on titanium foam substrates. All six formulations are commercially available from De Nora Tech. With each of the four redox couples (which are all at +1V vs NHE or higher) noticeable decay in the electrochemical performance of the felt electrodes was observed over one week on test. With the bromine and manganese electrolytes, significant weight loss of both the felt electrode and the graphite current collector was found, particularly for the positive (oxidizing) electrode in each cell. In the vanadium electrolyte, a distinct performance loss was observed; this is likely due to oxidation of the carbon surface as reported by Bourke et al [1,2]. The positive electrodes in the Vanadium cells lost between 2-10% of their weight. Several trials were conducted in this system as the weight loss results were less consistent than with the other chemistries. With the Ce couple, which has the highest potential, significant amounts of oxygen evolution (>50% of the total current) were observed with carbon felt, as well as the desired Ce3+ to Ce4+ reaction. All of the MMO formulations were highly active for each of the positive electrode chemistries, although there were differences in activity observed between the different electrodes as shown in Figure 1 below. For the vanadium and bromine electrolytes, the redox potential is sufficiently low such that oxygen evolution was minimal. For the manganese electrolyte, two of the MMO formulations yielded greater than 90% selectivity for manganese oxidation. For all of the MMO electrodes tested with the cerium couple, oxygen evolution is pre-dominate (>90% of the total current).

Transparent heaters made by ultrasonic spray pyrolysis of SnO2 on soda-lime glass substrates

Transparent heaters have become important owing to the increasing demand in automotive and display device manufacturing industries. Indium tin oxide (ITO) is the most commonly used material for production of transparent heaters, but the fabrication cost is high as the indium resources are diminishing fast. This has been the driving force behind the intense research for discovering more durable and cost-effective alternatives. Tin oxide, with its high temperature stability and coexisting high levels of conductivity and transparency, can replace expensive ITO in the fabrication of transparent heaters. Here, we propose tin oxide films deposited using ultrasonic spray pyrolysis as the raw material for the fabrication of transparent heaters. Silver contacts are paste printed on the deposited SnO2 layers, which provide the necessary connections to the external circuitry. Deposition of films having sheet resistance in the 150 Ω/□ range takes only ∼5 minutes and the utilized methods are fully scalable to mass production level. Durability tests, carried out for weeks of continuous operation at different elevated temperatures, demonstrated the long load life of the produced heaters.

An in vivo biosensing, biomimetic electrochemical transistor with applications in plant science and precision farming

The in vivo monitoring of key plant physiology parameters will be a key enabler of precision farming. Here, a biomimetic textile-based biosensor, which can be inserted directly into plant tissue is presented: the device is able to monitor, in vivo and in real time, variations in the solute content of the plant sap. The biosensor has no detectable effect on the plant’s morphology even after six weeks of continuous operation. The continuous monitoring of the sap electrolyte concentration in a growing tomato plant revealed a circadian pattern of variation. The biosensor has the potential to detect the signs of abiotic stress, and therefore might be exploited as a powerful tool to study plant physiology and to increase tomato growth sustainability. Also, it can continuously communicate the plant health status, thus potentially driving the whole farm management in the frame of smart agriculture.

Transparent heaters made by ultrasonic spray pyrolysis of nanograined SnO2 layers on soda-lime glass substrates

Transparent heaters have become important owing to the increasing demand in automotive and display device manufacturing industries. Indium tin oxide (ITO) is the most commonly used material for the production of transparent heaters, but the fabrication cost is high as the indium resources are diminishing fast. This has been the driving force behind the intense research for discovering more durable and cost-effective alternatives. Tin oxide, with its high temperature stability and coexisting high levels of conductivity and transparency, can replace expensive ITO in the fabrication of transparent heaters. Here, we propose nanograined tin oxide films deposited using ultrasonic spray pyrolysis as the raw material for the fabrication of transparent heaters. Silver contacts are paste printed on the deposited SnO2 layers, which provide the necessary connections to the external circuitry. Deposition of films having sheet resistance in the 120 Ω □−1 range takes only ~5 min and the utilized methods are fully scalable to the mass production level. Durability tests, carried out for weeks of continuous operation at different elevated temperatures, demonstrated the long load life of the produced heaters.

Rubidium-traced white-light etalon calibrator for radial velocity measurements at the cm s−1 level

We report on the construction and testing of a vacuum-gap Fabry-P\'erot etalon calibrator for high precision radial velocity spectrographs. Our etalon is traced against a rubidium frequency standard to provide a cost effective, yet ultra-precise wavelength reference. We describe here a turn-key system working at 500 nm to 900 nm, ready to be installed at any current and next generation radial velocity spectrograph that requires calibration over a wide spectral bandpass. Where appropriate, we have used off-the-shelf, commercial components with demonstrated long-term performance to accelerate the development timescale of this instrument. Our system combines for the first time the advantages of passively stabilized etalons for optical and near-infrared wavelengths with the laser-locking technique demonstrated for single-mode fiber etalons. We realize uncertainties in the position of one etalon line at the 10 cm/s level in individual measurements taken at 4 Hz. When binning the data over 10 s, we are able to trace the etalon line with a precision of better than 3 cm/s . We present data obtained during a week of continuous operation where we detect (and correct for) the predicted, but previously unobserved shrinking of the etalon Zerodur spacer corresponding to a shift of 13 cm/s per day.

Packaging of implantable accelerometers to monitor epicardial and endocardial wall motion.

Acceleration signals, collected from the inner and the outer heart wall, offer a mean of assessing cardiac function during surgery. Accelerometric measurements can also provide detailed insights into myocardial motion during exploratory investigations. Two different implantable accelerometers to respectively record endocardial and epicardial vibrations, have been developed by packaging a commercially available capacitive transducer. The same coating materials have been deposited on the two devices to ensure biocompatibility of the implants: Parylene-C, medical epoxy and Polydimethylsiloxane (PDMS). The different position-specific requirements resulted in two very dissimilar sensor assemblies. The endocardial accelerometer, that measures accelerations from the inner surface of the heart during acute animal tests, is a 2 mm-radius hemisphere fixed on a polymethyl methacrylate (PMMA) rod to be inserted through the heart wall. The epicardial accelerometer, that monitors the motion of the outer surface of the heart, is a three-legged structure with a stretchable polytetrafluoroethylene (PTFE) reinforcement. This device can follow the continuous motion of the myocardium (the muscular tissue of the heart) during the cardiac cycle, without hindering its natural movement. Leakage currents lower than 1 μA have been measured during two weeks of continuous operation in saline. Both transducers have been used, during animal tests, to simultaneously record and compare acceleration signals from corresponding locations on the inner and the outer heart wall of a female sheep.

Redox polymer with N,N‐dichlorosulfonamide functional groups as arsenite oxidant in aqueous solutions

ABSTRACTA macroporous, styrene‐divinylbenzene polymer with N,N‐dichlorosulfonamide functional groups (SO2NCl2), containing two chlorine atoms with oxidation number +1, have been prepared through the chemical modification of a commercial sulfonic cation exchanger (Amberlyst 15, Rohm and Haas). Obtained product was used as the heterogeneous oxidant of As(III) in aqueous solutions. The polymer's oxidizing capacity, determined as part of the batch studies, amounted to 193.29 mg As(III) g−1 (pH = 7.7) and 206.03 mg As(III) g−1 (pH = 2.0). The suitability of the redox polymer for long‐lasting operation in the aqueous environment was confirmed in the column study conducted using a solution with a concentration of 10 mg As(III) dm−3 at a flow rate of 6 bed volumes (BV) h−1. The concentration of As(III) in the effluent reached the value of 0.01 mg As(III) dm−3 only after 8 weeks of continuous operation when 7930 BV of the solution had passed through the bed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41552.

Commercial activated carbon for the catalytic production of hydrogen via the sulfur–Iodine thermochemical water splitting cycle

Eight commercial activated carbon catalysts were examined for their catalytic activity to decompose hydroiodic acid (HI) to produce hydrogen; a key reaction in the sulfur–iodine (S–I) thermochemical water splitting cycle. Activity was examined under a temperature ramp from 473 to 773 K. No statistically significant correlation was found between the measured catalyst sample properties and catalytic activity. Four of the eight samples were examined for one week of continuous operation at 723 K. All samples appeared to be stable over the period of examination.

HYDROISOMERIZATION OF 1-PENTENE TO ISO-PENTANE IN A SINGLE REACTOR

It has been shown that hydroisomerization of an olefinic feed to an iso-paraffinic product can be performed in a single reactor using a platinum on mordenite (Pt-MOR) zeolite catalyst. This conversion finds application in a Fischer-Tropsch refinery where the syncrude is rich in olefins and conventional hydroisomerization would require hydrogenation of the feed as a feed pretreatment step. In order to demonstrate that the proposed process configuration is viable from a catalysis point of view, the hydroisomerization of 1-pentene over Pt-MOR has been investigated experimentally in the range 200°–270°C, 2 MPa, WHSV 1–3 h−1, and H2:1-pentene molar ratio of 3:1–5:1. The catalyst was stable during one week of continuous operation. The highest iso-pentane yield (69%) was obtained at 250°C. Side reactions (dimerization and cracking) increased with increasing temperature, decreasing H2:1-pentene ratio, and increasing space velocity.

High-temperature sulfuric acid decomposition over complex metal oxide catalysts

Abstract Activity and stability of FeTiO 3 , MnTiO 3 , NiFe 2 O 4 , CuFe 2 O 4 , NiCr 2 O 4 , 2CuO·Cr 2 O 3 , CuO and Fe 2 O 3 for the atmospheric decomposition of concentrated sulfuric acid in sulfur-based thermochemical water splitting cycles are presented. Catalyst activity was determined at temperatures from 725 to 900 °C. Catalytic stability was examined at 850 °C for up to 1 week of continuous operation. The results were compared to a 1.0 wt% Pt/TiO 2 catalyst. Surface area by nitrogen physisorption, X-ray diffraction analyses, and temperature programmed desorption and oxidation were used to characterize fresh and spent catalyst samples. Over the temperature range, the catalyst activity of the complex oxides followed the general trend: 2CuO·Cr 2 O 3 > CuFe 2 O 4 > NiCr 2 O 4 ≈ NiFe 2 O 4 > MnTiO 3 ≈ FeTiO 3 . At temperatures less than 800 °C, the 1.0 wt% Pt/TiO 2 catalyst had higher activity than the complex oxides, but at temperatures above 850 °C, the 2CuO·Cr 2 O 3 and CuFe 2 O 4 samples had the highest activity. Surface area was found to decrease for all of the metal oxides after exposure to reaction conditions. In addition, the two complex metal oxides that contained chromium were not stable in the reaction environment; both leached chromium into the acid stream and decomposed into their individual oxides. The FeTiO 3 sample also produced a discoloration of the reactor due to minor leaching and converted to Fe 2 TiO 5 . Fe 2 O 3 , MnTiO 3 and NiFe 2 O 4 were relatively stable in the reaction environment. In addition, CuFe 2 O 4 catalyst appeared relatively promising due to its high activity and lack of any leaching issues; however it deactivated in week-long stability experiments. Complex metal oxides may provide an attractive alternative to platinum-based catalyst for the decomposition of sulfuric acid; however, the materials examined in this study all displayed shortcomings including material sintering, phase changes, low activity at moderated temperatures due to sulfate formation, and decomposition to their individual oxides. More effort is needed in this area to discover metal oxide materials that are less expensive, more active and more stable than platinum catalysts.