The chemical looping strategy offers a potentially viable option for efficient carbonaceous fuel conversion with a reduced carbon footprint. In the chemical looping process, an oxygen carrier is reduced and oxidized in a cyclic manner to convert a carbonaceous fuel into separate streams of concentrated carbon dioxide and carbon-free products such as electricity and/or hydrogen. The reactivity and chemical and physical stability of the oxygen carrier are of pivotal importance to chemical looping processes. A typical oxygen carrier is composed of a multi-valence transition metal oxide supported on an “inert” support. Although the support does not get reduced or oxidized at any significant extent, numerous studies have indicated that certain supports such as TiO2 and Al2O3 can improve oxygen carrier stability and/or reactivity. This study reports the use of mixed ionic–electronic conductive support in iron-based oxygen carriers. By incorporating a perovskite-based mixed conductive support such as lanthanum strontium ferrite (LSF), the reactivity of the oxygen carrier is enhanced by 5–70 times when compared to oxygen carriers with conventional TiO2-, Al2O3-, or yttria-stabilized zirconia (YSZ) support. The mixed conductivity enhanced oxygen carrier also shows good stability and coke resistance. Characterization studies indicate that the enhanced oxygen carrier is composed of intermixed nanoscale (<100 nm) crystallites of iron oxide and support. The mixed conductive support enables facile O2– transport to and from the iron oxide nanocrystallites to participate in the surface redox reactions. The support also allows counter-current or concurrent diffusion of electrons or holes to maintain charge balance within the oxygen carrier. With iron oxide as the nanoscale oxygen source and mixed conductive support as the oxygen/electron conductor, the mixed conductivity enhanced oxygen carrier particle can be considered as an ensemble of nanoscale mixed conductive membrane reactors that possess excellent redox activity.

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A crucial challenge for the commercialization of Ni-rich layered cathodes (LiNi0.88Co0.09Al0.03O2) is capacity decay during the cycling process, which originates from their interfacial instability and structural degradation. Herein, a one-step, dual-modified strategy is put forward to in situ synthesize the yttrium (Y)-doped and yttrium orthophosphate (YPO4)-modified LiNi0.88Co0.09Al0.03O2 cathode material. It is confirmed that the YPO4 coating layer as a good ion conductor can stabilize the solid–electrolyte interface, while the formative strong Y–O bond can bridle TM–O slabs to intensify the lattice structure in the state of deep delithium (>4.3 V). In particular, both the combined advantages effectively withstand the anisotropic strain generated upon the H2–H3 phase transition and further alleviate the crack generation in unit-cell dimensions, assuring a high-capacity delivery and fast Li+ diffusion kinetics. This dual-modified cathode shows advanced cycling stability (94.1% at 1C after 100 cycles in 2.7–4.3 V), even at a high cutoff voltage and high rate, and advanced rate capability (159.7 mAh g–1 at 10C). Therefore, it provides a novel solution to achieve both high capacity and highly stable cyclability in Ni-rich cathode materials.

Efficient and environmentally friendly conversion of methane into syngas is a topic of practical relevance for the production of hydrogen, chemicals, and synthetic fuels. At present, methane‐derived syngas is produced primarily through the steam methane reforming processes. The efficiencies of such processes are limited owing to the endothermic steam methane reforming reaction and the high steam to methane ratio required by the reforming catalysts. Chemical looping reforming represents an alternative approach for methane conversion. In the chemical looping reforming scheme, a solid oxygen carrier or “redox catalyst” is used to partially oxidize methane to syngas. The reduced redox catalyst is then regenerated with air. The cyclic redox operation reduces the steam usage while simplifying the heat integration scheme. Herein, a new Fe2O3@LaxSr1−xFeO3 (LSF) core–shell redox catalyst is synthesized and investigated. Compared with several other commonly investigated iron‐based redox catalysts, the newly developed core–shell redox catalyst is significantly more active and selective for syngas production from methane. It is also more resistant toward carbon formation and maintains high activity over cyclic redox operations.

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The Ni-rich layered oxides are considered as a candidate of next-generation cathode materials for high energy density lithium-ion batteries; however, the finite cyclic life and poor thermostability impede their practical applications. There is often a tradeoff between structure stability and high capacity because the intrinsical instability of oxygen framework will lead to the structural transformation of Ni-rich materials. Because of the strong binding energy between the Te atom and O atom, herein a new technology of surface tellurium (Te) doping in the Ni-rich layered oxide (LiNi0.88Co0.09Al0.03O2) is proposed to settle the above predicament. Based on density function theory calculations and experiment analysis, it has been confirmed that the doped Te6+ ions are positioned in the TM layer near the oxide surface, which can constrain the TM–O slabs by strong Te–O bonds and prevent oxygen release from the surface, thus enhancing the stability of the lattice framework in deep delithium (>4.3 V). Especially, 1 wt % Te doping (Te 1%-NCA) shows the superiority in performance improvement. Furthermore, the reversibility of H2–H3 phase transition is also improved to relieve effectively the capacity decline and the structural transformations at extended cycling, which can facilitate the fast Li+ diffusion kinetic. Consequently, Te 1%-NCA cathode exhibits the improved cycling stability even at high voltages (4.5 and 4.7 V), good rate capability (159.2 mA h g–1 at 10 C), and high thermal stability (the peak temperature of 258 °C). Therefore, the appropriate Te surface doping provides a significant exploration for industrial development of the high-performance Ni-rich cathode materials with high capacity and structural stability.

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