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In ferrite-based thermochemical looping, the maximum oxygen exchange capacity usually occurs at iron-poor compositions, even when iron is the redox active element. The underlying causes are uncovered by thermodynamic and phase diagram analyses.

Dissociation of CO2 to form CO can play a key role in decarbonizing our energy system. We report here a two-step thermochemical cycle using a variety of iron-poor (Fe-poor) ferrites (FeyM1−yOx where y < 2/3) that produce CO with unusually high yield using Fe as the redox active species. Conventional wisdom suggests that increasing the Fe fraction would increase the capacity for CO2 dissociation. Here, we report the opposite result: at partial pressure ratio CO : CO2 = 1 : 100, we demonstrated CO yields of 8.0 ± 1.0 mL-CO per gram from Fe0.35Ni0.65Ox, and 3.7 ± 1.0 mL-CO per gram from Fe0.45Co0.55Ox, at a thermal reduction temperature of 1300 °C; remarkably, these CO2 dissociation capacities are significantly higher than those of state-of-the-art materials such as spinel ferrites (Fe2MO4), (substituted) ceria, and Mn-based perovskite oxides. Optimization of the kinetics of Fe-poor ferrites with a ZrO2 support resulted in higher CO yields per gram of ferrite. The unexpected CO yield vs. Fe ratio trend is consistent with the prediction of calculated ternary phase diagrams, which suggest a swing between spinel and rocksalt phases. These Fe-poor ferrites open new opportunities for tuning the redox properties of oxygen exchange materials.

We report the discovery of a new class of oxides – poly-cation oxides (PCOs) – that consist of multiple cations and can thermochemically split water in a two-step cycle to produce hydrogen (H2) and oxygen (O2). Specifically, we demonstrate H2 yields of 10.1 ± 0.5 mL-H2 per g and 1.4 ± 0.5 mL-H2 per g from (FeMgCoNi)Ox (x ≈ 1.2) with thermal reduction temperatures of 1300 °C and 1100 °C, respectively, and also with background H2 during the water splitting step. Remarkably, these capacities are mostly higher than those from measurements and thermodynamic analysis of state-of-the-art materials such as (substituted) ceria and spinel ferrites. Such high-performance two-step cycles ≤1100 °C are practically relevant for today's chemical infrastructure at large scale, which relies almost exclusively on thermochemical transformations in this temperature regime. It is likely that PCOs with complex cation compositions will offer new opportunities for both fundamental investigations of redox thermochemistry as well as scalable H2 production using infrastructure-compatible chemical systems.

Dual-mode textiles made of nanoPE provide both cooling and heating, which helps humans adapt to larger temperature changes., Maintaining human body temperature is one of the most basic needs for living, which often consumes a huge amount of energy to keep the ambient temperature constant. To expand the ambient temperature range while maintaining human thermal comfort, the concept of personal thermal management has been recently demonstrated in heating and cooling textiles separately through human body infrared radiation control. Realizing these two opposite functions within the same textile would represent an exciting scientific challenge and a significant technological advancement. We demonstrate a dual-mode textile that can perform both passive radiative heating and cooling using the same piece of textile without any energy input. The dual-mode textile is composed of a bilayer emitter embedded inside an infrared-transparent nanoporous polyethylene (nanoPE) layer. We demonstrate that the asymmetrical characteristics of both emissivity and nanoPE thickness can result in two different heat transfer coefficients and achieve heating when the low-emissivity layer is facing outside and cooling by wearing the textile inside out when the high-emissivity layer is facing outside. This can expand the thermal comfort zone by 6.5°C. Numerical fitting of the data further predicts 14.7°C of comfort zone expansion for dual-mode textiles with large emissivity contrast.

Epidemiological studies have shown that exposure to airborne particles is strongly associated with human health. Air quality concerns in aircraft cabins increase as air travel is becoming more common. Analyzing factors that influence the concentrations of airborne particles and taking mitigating measures will protect human health during air travel. In this study, concentrations of particles larger than 0.3 μm were measured in aircrafts' supply air in 9 flights. Air change rates were evaluated by the concentration of CO 2 in supply air and recirculation air. Human emission, deposition and resuspension of particles were analyzed with our previously published results. The state-space method was used to calculate time-dependent particle concentration in different particle diameter intervals. Afterwards, with variation ranges of the 5 factors above, deviation rates of particle concentration were defined to evaluate the importance of those factors. This study determined: 1) resuspension is not an important factor, especially as time elapses; 2) varied deposition rate slightly influences particles smaller than 5.0 μm; 3) air change rate and human emission rate strongly impact the concentration of particles smaller than 2.0 μm; 4) supply air concentration generally affects the concentration of larger particles.

The solubilities of La and Ni on LaNiO3 in Li/K carbonate eutectic with La2O3 have been investigated. The solubilities of La and Ni were 1.9 × 10−2 (mole fraction) and 1.2 × 10−5 (mole fraction) un...