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1. A New Type of Li‐Rich Rock‐Salt Oxide Li 2 Ni 1/3 Ru 2/3 O 3 with Reversible Anionic Redox Chemistry

   https://doi.org/10.1002/adma.201807825  

   Li, Xiang ; Qiao, Yu ; Guo, Shaohua ; Jiang, Kezhu ; Ishida, Masayoshi ; Zhou, Haoshen ( January 2019 , Advanced Materials)

   Li‐rich oxide cathodes are of prime importance for the development of high‐energy lithium‐ion batteries (LIBs). Li‐rich layered oxides, however, always undergo irreversible structural evolution, leading to inevitable capacity and voltage decay during cycling. Meanwhile, Li‐rich cation‐disordered rock‐salt oxides usually exhibit sluggish kinetics and inferior cycling stability, despite their firm structure and stable voltage output. Herein, a new Li‐rich rock‐salt oxide Li₂Ni_1/3Ru_2/3O₃withFd‐3mspace group, where partial cation‐ordering arrangement exists in cationic sites, is reported. Results demonstrate that a cathode fabricated from Li₂Ni_1/3Ru_2/3O₃delivers a large capacity, outstanding rate capability as well as good cycling performance with negligible voltage decay, in contrast to the common cations disordered oxides with space groupFm‐3m. First principle calculations also indicate that rock‐salt oxide with space groupFd‐3mpossesses oxygen activity potential at the state of delithiation, and good kinetics with more 0‐TM (TM = transition metals) percolation networks. In situ Raman results confirm the reversible anionic redox chemistry, confirming O²⁻/O⁻evolution during cycles in Li‐rich rock‐salt cathode for the first time. These findings open up the opportunity to design high‐performance oxide cathodes and promote the development of high‐energy LIBs.

    

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2. Modified Ceria for “Low‐Temperature” CO 2 Utilization: A Chemical Looping Route to Exploit Industrial Waste Heat

   https://doi.org/10.1002/aenm.201901963  

   Haribal, Vasudev_Pralhad ; Wang, Xijun ; Dudek, Ryan ; Paulus, Courtney ; Turk, Brian ; Gupta, Raghubir ; Li, Fanxing ( September 2019 , Advanced Energy Materials)

   Efficient CO₂utilization is key to limit global climate change. Carbon monoxide, which is a crucial feedstock for chemical synthesis, can be produced by splitting CO₂. However, existing thermochemical routes are energy intensive requiring high operating temperatures. A hybrid redox process (HRP) involving CO₂‐to‐CO conversion using a lattice oxygen‐deprived redox catalyst at relatively low temperatures (<700 °C) is reported. The lattice oxygen of the redox catalyst, restored during CO₂‐splitting, is subsequently used to convert methane to syngas. Operated at temperatures significantly lower than a number of industrial waste heat sources, this cyclic redox process allows for efficient waste heat‐utilization to convert CO₂. To enable the low temperature operation, lanthanum modified ceria (1:1 Ce:La) promoted by rhodium (0.5 wt%) is reported as an effective redox catalyst. Near‐complete CO₂conversion with a syngas yield of up to 83% at low temperatures is achieved using Rh‐promoted LaCeO_4−x. While La improves low‐temperature bulk redox properties of ceria, Rh considerably enhances the surface catalytic properties for methane activation. Density functional theory calculations further illustrate the underlying functions of La‐substitution. The highly effective redox catalyst and HRP scheme provide a potentially attractive route for chemical production using CO₂, industrial waste heat, and methane, with appreciably lowered CO₂emissions.

    

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3. Lithium carbonate-promoted mixed rare earth oxides as a generalized strategy for oxidative coupling of methane with exceptional yields

   https://doi.org/10.1038/s41467-023-43682-5  

   Zhao, Kun ; Gao, Yunfei ; Wang, Xijun ; Lis, Bar Mosevitzky ; Liu, Junchen ; Jin, Baitang ; Smith, Jacob ; Huang, Chuande ; Gao, Wenpei ; Wang, Xiaodong ; et al ( November 2023 , Nature Communications)

   The oxidative coupling of methane to higher hydrocarbons offers a promising autothermal approach for direct methane conversion, but its progress has been hindered by yield limitations, high temperature requirements, and performance penalties at practical methane partial pressures (~1 atm). In this study, we report a class of Li₂CO₃-coated mixed rare earth oxides as highly effective redox catalysts for oxidative coupling of methane under a chemical looping scheme. This catalyst achieves a single-pass C₂₊yield up to 30.6%, demonstrating stable performance at 700 °C and methane partial pressures up to 1.4 atm. In-situ characterizations and quantum chemistry calculations provide insights into the distinct roles of the mixed oxide core and Li₂CO₃shell, as well as the interplay between the Pr oxidation state and active peroxide formation upon Li₂CO₃coating. Furthermore, we establish a generalized correlation between Pr⁴⁺content in the mixed lanthanide oxide and hydrocarbons yield, offering a valuable optimization strategy for this class of oxidative coupling of methane redox catalysts.

    

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4. Enhanced CO 2 electrolysis with a SrTiO 3 cathode through a dual doping strategy

   https://doi.org/10.1039/c8ta10188d  

   Ye, Lingting ; Hu, Xiuli ; Wang, Xin ; Chen, Fanglin ; Tang, Dian ; Dong, Dehua ; Xie, Kui ( February 2019 , Journal of Materials Chemistry A)

   The significant role of perovskite defect chemistry through A-site doping of strontium titanate with lanthanum for CO 2 electrolysis properties is demonstrated. Here we present a dual strategy of A-site deficiency and promoting adsorption/activation by making use of redox active dopants such as Mn/Cr linked to oxygen vacancies to facilitate CO 2 reduction at perovskite titanate cathode surfaces. Solid oxide electrolysers based on oxygen-excess La 0.2 Sr 0.8 Ti 0.9 Mn(Cr) 0.1 O 3+δ , A-site deficient (La 0.2 Sr 0.8 ) 0.9 Ti 0.9 Mn(Cr) 0.1 O 3−δ and undoped La 0.2 Sr 0.8 Ti 1.0 O 3+δ cathodes are evaluated. In situ infrared spectroscopy reveals that the adsorbed and activated CO 2 adopts an intermediate chemical state between a carbon dioxide molecule and a carbonate ion. The double strategy leads to optimal performance being observed after 100 h of high-temperature operation and 3 redox cycles, suggesting a promising cathode material for CO 2 electrolysis. 

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5. A tailored multi-functional catalyst for ultra-efficient styrene production under a cyclic redox scheme

   https://doi.org/10.1038/s41467-021-21374-2  

   Zhu, Xing ; Gao, Yunfei ; Wang, Xijun ; Haribal, Vasudev ; Liu, Junchen ; Neal, Luke M. ; Bao, Zhenghong ; Wu, Zili ; Wang, Hua ; Li, Fanxing ( February 2021 , Nature Communications)

   Styrene is an important commodity chemical that is highly energy and CO₂intensive to produce. We report a redox oxidative dehydrogenation (redox-ODH) strategy to efficiently produce styrene. Facilitated by a multifunctional (Ca/Mn)_1−xO@KFeO₂core-shell redox catalyst which acts as (i) a heterogeneous catalyst, (ii) an oxygen separation agent, and (iii) a selective hydrogen combustion material, redox-ODH auto-thermally converts ethylbenzene to styrene with up to 97% single-pass conversion and >94% selectivity. This represents a 72% yield increase compared to commercial dehydrogenation on a relative basis, leading to 82% energy savings and 79% CO₂emission reduction. The redox catalyst is composed of a catalytically active KFeO₂shell and a (Ca/Mn)_1−xO core for reversible lattice oxygen storage and donation. The lattice oxygen donation from (Ca/Mn)_1−xO sacrificially stabilizes Fe³⁺in the shell to maintain high catalytic activity and coke resistance. From a practical standpoint, the redox catalyst exhibits excellent long-term performance under industrially compatible conditions.

    

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