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1. Ruddlesden–Popper Structured Sr ₃ Fe ₂ O _7−δ as Redox‐Activated CO ₂ Sorbents for Green Hydrogen Production

   https://doi.org/10.1002/aesr.202500213  

   Rukh, Mahe; Cai, Runxia; Razavi, Seyedamin; Portillo, Sam; Yao, Yuge; Neal, Luke; Li, Fanxing (January 2026, Advanced Energy and Sustainability Research)

   Conventional methods for hydrogen production, such as steam methane reforming, face increasing scrutiny due to their reliance on fossil fuels, high CO₂emissions, and significant capital costs. Sorption‐enhanced steam reforming using renewable feedstocks, where CO₂is captured in situ, presents a more sustainable alternative. This study investigates the suitability of A‐ and B‐site doped strontium ferrite‐type Ruddlesden–Popper oxides (RPO) as robust CO₂sorbents, with particular attention on their application in glycerol‐based hydrogen production. Packed bed reactor experiments, complemented by comprehensive characterizations, are systematically conducted to assess and compare the performance of RPO with a stoichiometry of (Sr_xCa_1−x)₂Fe_0.9Ni_0.1O_4−δ(RPOs) with that of traditional perovskite oxides, that is, Sr_xCa_1−xFe_0.9Ni_0.1O_4−δ(POs), and to unravel the underlying phase transition pathways. Specifically, RPO with a nominal stoichiometry of Sr_1.4Ca_0.6Fe_0.9Ni_0.1O_4−δforms an Sr₃Fe₂O_7‐type active phase, exhibiting high H₂purities (≈95 vol%) coupled with stable CO₂sorption capacity. Notably, its CO₂prebreakthrough time is more than six times longer than that of its perovskite counterpart in the sequential Ni‐bed configuration. Finally, the interplay between the reduction and carbonation reactions is examined, highlighting the synergistic benefits that enable the sorbent to fully realize its CO₂uptake potential. 

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2. Ce stabilized Ni–SrO as a catalytic phase transition sorbent for integrated CO ₂ capture and CH ₄ reforming

   https://doi.org/10.1039/D1TA09967A  

   Gu, Haiming; Gao, Yunfei; Iftikhar, Sherafghan; Li, Fanxing (February 2022, Journal of Materials Chemistry A)

   Integration of carbon dioxide capture from flue gas with dry reforming of CH 4 represents an attractive approach for CO 2 utilization. The selection of a suitable bifunctional material serving as a catalyst/sorbent is the key. This paper reports Ni decorated and CeO x -stabilized SrO (SrCe 0.5 Ni 0.5 ) as a multi-functional, phase transition catalytic sorbent material. The effect of CeO x on the morphology, structure, decarbonation reactivity, and cycling stability of the catalytic sorbent was determined with TEM-EDX, XRD, in situ XRD, CH 4 -TPR and TGA. Cyclic process tests were conducted in a packed bed reactor. The results indicate that large Ni clusters were present on the surface of the SrNi sorbent, and the addition of CeO 2 promoted even distribution of Ni on the surface. Moreover, the Ce–Sr interaction promoted a complex carbonation/decarbonation phase-transition, i.e. SrCO 3 + CeO 2 ↔ Sr 2 CeO 4 + CO 2 as opposed to the conventional, simple carbonation/decarbonation cycles ( e.g. SrCO 3 ↔ SrO + CO 2 ). This double replacement crystalline phase transition mechanism not only adjusts the carbonation/calcination thermodynamics to facilitate SrCO 3 decomposition at relatively low temperatures but also inhibits sorbent sintering. As a result, excellent activity and stability were observed with up to 91% CH 4 conversion, >72% CO 2 capture efficiency and ∼100% residual O 2 capture efficiency from flue gas by utilizing the CeO 2 ↔ Ce 2 O 3 redox transition. This renders an intensified process with zero coke deposition. Moreover, the SLDRM with SrCe 0.5 Ni 0.5 has the flexibility to produce concentrated CO via CO 2 -splitting while co-producing a syngas with tunable H 2 /CO ratios. 

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3. Advanced oxygen-electrode-supported solid oxide electrochemical cells with Sr(Ti,Fe)O _3−δ -based fuel electrodes for electricity generation and hydrogen production

   https://doi.org/10.1039/d0ta06678h  

   Zhang, Shan-Lin; Wang, Hongqian; Yang, Tianrang; Lu, Matthew Y.; Li, Cheng-Xin; Li, Chang-Jiu; Barnett, Scott A. (December 2020, Journal of Materials Chemistry A)

   null (Ed.)

   Sr(Ti 0.3 Fe 0.7 )O 3−δ (STF) and the associated exsolution electrodes Sr 0.95 (Ti 0.3 Fe 0.63 Ru 0.07 )O 3−δ (STFR), or Sr 0.95 (Ti 0.3 Fe 0.63 Ni 0.07 )O 3−δ (STFN) are alternatives to Ni-based cermet fuel electrodes for solid oxide electrochemical cells (SOCs). They can provide improved tolerance to redox cycling and fuel impurities, and may allow direct operation with hydrocarbon fuels. However, such perovskite-oxide-based electrodes present processing challenges for co-sintering with thin electrolytes to make fuel electrode supported SOCs. Thus, they have been mostly limited to electrolyte-supported SOCs. Here, we report the first example of the application of perovskite oxide fuel electrodes in novel oxygen electrode supported SOCs (OESCs) with thin YSZ electrolytes, and demonstrate their excellent performance. The OESCs have La 0.8 Sr 0.2 MnO 3−δ –Zr 0.92 Y 0.16 O 2−δ (LSM–YSZ) oxygen electrode-supports that are enhanced via infiltration of SrTi 0.3 Fe 0.6 Co 0.1 O 3−δ , while the fuel electrodes are either Ni-YSZ, STF, STFN, or STFR. Fuel cell power density as high as 1.12 W cm −2 is obtained at 0.7 V and 800 °C in humidified hydrogen and air with the STFR electrode, 60% higher than the same cell made with a Ni-YSZ electrode. Electrolysis current density as high as −1.72 A cm −2 is obtained at 1.3 V and 800 °C in 50% H 2 O to 50% H 2 mode; the STFR cell yields a value 72% higher than the same cell made with a Ni-YSZ electrode, and competitive with the widely used conventional Ni-YSZ-supported cells. The high performance is due in part to the low resistance of the thin YSZ electrolyte, and also to the low fuel electrode polarization resistance, which decreases with fuel electrode in the order: Ni-YSZ > STF > STFN > STFR. The high performance of the latter two electrodes is due to exsolution of catalytic metal nanoparticles; the results are discussed in terms of the microstructure and properties of each electrode material, and surface oxygen exchange resistance values are obtained over a range of conditions for STF, STFN, and STFN. The STF fuel electrodes also provide good stability during redox cycling. 

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4. Robust redox-reversible perovskite type steam electrolyser electrode decorated with in situ exsolved metallic nanoparticles

   https://doi.org/10.1039/c9ta06309a  

   Liu, Tong; Zhao, Yiqian; Zhang, Xiaoyu; Zhang, Hong; Jiang, Guang; Zhao, Wen; Guo, Jiayi; Chen, Fanglin; Yan, Mufu; Zhang, Yanxiang; et al (January 2020, Journal of Materials Chemistry A)

   Redox stabilities of the hydrogen electrode with in situ exsolved Fe–Ni nanoparticles from Sr 2 Fe 1.4 Ni 0.1 Mo 0.5 O 6−δ (SFMNi) perovskite are studied by analyzing the evolution of the phase composition and morphology during the redox cycles. It is found that certain amount of the exsolved nanoparticles have been oxidized to the transition metal oxide (Ni,Fe)O instead of reincorporating into the parent perovskite lattice upon re-oxidizing at 800 °C in air. However, the (Ni,Fe)O secondary phases show no adverse effect on the subsequent reduction treatment. The redox reversibility mechanism is explained by the regular-solution model. The electrodes are almost fully recovered in the reducing atmosphere, and the symmetrical cells measured under 9.7% H 2 –3% H 2 O–87.3% N 2 conditions show a stable specific area polarization resistance of around 1.93 Ω cm 2 at 800 °C during 13 redox cycles. Single cells using the Ni–Fe nanoparticles structured electrode exhibit a stable electrode polarization resistance of about 0.598 Ω cm 2 at 800 °C under open circuit voltage conditions and a steady electrolysis current density of about −653 mA cm −2 at 1.5 V during the steam electrolysis process over 5 redox cycles. These results indicate that the SFMNi material is a very promising electrode candidate for steam electrolysis application with robust redox reversibility. 

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5. Power and carbon monoxide co-production by a proton-conducting solid oxide fuel cell with La _0.6 Sr _0.2 Cr _0.85 Ni _0.15 O _3−δ for on-cell dry reforming of CH ₄ by CO ₂

   https://doi.org/10.1039/D0TA03458D  

   Wei, Tong; Qiu, Peng; Jia, Lichao; Tan, Yuan; Yang, Xin; Sun, Shichen; Chen, Fanglin; Li, Jian (May 2020, Journal of Materials Chemistry A)

   null (Ed.)

   To directly use a CO 2 –CH 4 gas mixture for power and CO co-production by proton-conducting solid oxide fuel cells (H-SOFCs), a layer of in situ reduced La 0.6 Sr 0.2 Cr 0.85 Ni 0.15 O 3−δ (LSCrN@Ni) is fabricated on a Ni–BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) anode-supported H-SOFC (H-DASC) for on-cell CO 2 dry reforming of CH 4 (DRC). For demonstrating the effectiveness of LSCrN@Ni, a cell without adding the LSCrN@Ni catalyst (H-CASC) is also studied comparatively. Fueled with H 2 , both H-CASC and H-DASC show similar stable performance with a maximum power density ranging from 0.360 to 0.816 W cm −2 at temperatures between 550 and 700 °C. When CO 2 –CH 4 is used as the fuel, the performance and stability of H-CASC decreases considerably with a maximum power density of 0.287 W cm −2 at 700 °C and a sharp drop in cell voltage from the initial 0.49 to 0.10 V within 20 h at 0.6 A cm −2 . In contrast, H-DASC demonstrates a maximum power density of 0.605 W cm −2 and a stable cell voltage above 0.65 V for 65 h. This is attributed to highly efficient on-cell DRC by LSCrN@Ni. 

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