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1. Self‐Regenerative Ni‐Doped CaTiO ₃ /CaO for Integrated CO ₂ Capture and Dry Reforming of Methane

   https://doi.org/10.1002/smll.202401156  

   Jo, Seongbin; Gilliard‐AbdulAziz, Kandis Leslie (April 2024, Small)

   Abstract In this work, a new type of multifunctional materials (MFMs) called self‐regenerative Ni‐doped CaTiO₃/CaO is introduced for the integrated CO₂capture and dry reforming of methane (ICCDRM). These materials consist of a catalytically active Ni‐doped CaTiO₃and a CO₂sorbent, CaO. The article proposes a concept where the Ni catalyst can be regenerated in situ, which is crucial for ICCDRM. Exsolved Ni nanoparticles are evenly distributed on the surface of CaTiO₃under H₂or CH₄, and are re‐dispersed back into the CaTiO₃lattice under CO₂. The Ni‐doped CaTiO₃/CaO MFMs show stable CO₂capture capacity and syngas productivity for 30 cycles of ICCDRM. The presence of CaTiO₃between CaO grains prevents CaO/CaCO₃thermal sintering during carbonation and decarbonation. Moreover, the strong interaction of CaTiO₃with exsolved Ni mitigates severe accumulation of coke deposition. This concept can be useful for developing MFMs with improved properties that can advance integrated carbon capture and conversion. 

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2. Co/Co ₂ P Nanoparticles Encapsulated within Hierarchically Porous Nitrogen, Phosphorus, Sulfur Co‐doped Carbon as Bifunctional Electrocatalysts for Rechargeable Zinc‐Air Batteries

   https://doi.org/10.1002/celc.202101246  

   Wang, Likai; Sun, Yinggang; Zhang, Shenzhi; Di, Hexiang; Liu, Qiming; Du, Xin; Li, Zhongfang; Yang, Kai; Chen, Shaowei (November 2021, ChemElectroChem)

   Abstract Developing high performance nonprecious metal‐based electrocatalysts has become a critical first step towards commercial applications of metal‐air batteries. Herein, nanocomposites based on Co/Co₂P nanoparticles encapsulated within hierarchically porous N, P, S co‐doped carbon are prepared by controlled pyrolysis of zeolitic imidazolate frameworks (ZIF‐67) and poly(cyclotriphosphazene‐co‐4,4’‐sulfonyldiphenol) (PZS). The resulting Co/Co₂P@NPSC nanocomposites exhibit apparent oxygen reduction reaction (ORR) and evolution reaction (OER) catalytic performance, and are used as the reversible oxygen catalyst for zinc‐air batteries (ZABs). Density functional theory (DFT) calculations exhibit that Co₂P could provide active sites for the ORR and promote the conversion between the adsorbed intermediates, and porous N,P,S co‐doped carbon with Co₂P nanoparticles also improves the exposure of actives sites and endows charge transport. Liquid‐state ZABs with Co/Co₂P@NPSC as the cathode catalysts demonstrate the greater power density of 198.1 mW cm⁻²and a long cycling life of 50 h at 10 mA cm⁻², likely due to the encapsulation of Co/Co₂P nanoparticles by the carbon shell. Solid‐state ZABs also display a remarkable performance with a high peak power density of 74.3 mW cm⁻². Therefore, this study indicates the meaning of the design and engineering of hierarchical porous carbon nanomaterial as electrocatalyst for rechargeable metal‐air batteries. 

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3. Chemical Stability of BaMg _0.33 Nb _0.67-X Fe _x O _3-δ in High Temperature Methane Conversion Environments

   https://doi.org/10.1149/11106.0587ecst  

   Denoyer, Luke H; Benavidez, Angelica; Brearley, Adrian; Ramaiyan, Kannan; Garzon, Fernando H. (May 2023, ECS Transactions)

   Doped perovskite metal oxide catalysts of the form A(B_xM_1-x)O_3-δhave been instrumental in the development of solid oxide electrolyzers/fuel cells. In addition, this material class has also been demonstrated to be effective as a heterogeneous catalyst. Co-doped barium niobate perovskites have shown remarkable stability in highly acidic CO₂sensing measurements/environments (1). However, the reason for their chemical stability is not well understood. Doping with transition metal cations for B site cations often leads to exsolution under reducing conditions. Many perovskites used for the oxidative coupling of methane (OCM) or the electrochemical oxidative coupling of methane (E-OCM) either lack long term stability, or catalytic activity within these highly reducing methane environments. The Mg and Fe co-doped barium niobate BaMg_0.33Nb_0.67-xFe_xO_3-δshown activity in E-OCM reactors over long periods (2) (>100 hrs) with no iron metal exsolution observed by diffraction or STEM EDX measurements. In contrast, iron decorated BaMg_0.33Nb_0.67O₃showed little C2 conversion activity. 

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4. Propane oxidative dehydrogenation using CO ₂ over CrO _x /Fe–CeO ₂ catalysts

   https://doi.org/10.1039/D2CY01563C  

   Wang, Hedun; Nguyen, Thu D.; Tsilomelekis, George (April 2023, Catalysis Science & Technology)

   The kinetic behavior of CrO_xsites supported on Fe doped CeO₂was studied for CO₂-assisted propane oxidative dehydrogenation. 

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5. Recent progress in electrochemical reduction of carbon dioxide on metal single‐atom catalysts

   https://doi.org/10.1002/ese3.1036  

   Huo, Siming; Lu, Jessie; Wang, Xianqin (December 2021, Energy Science & Engineering)

   Abstract Electrochemical reduction reaction of CO₂(CO₂RR) is a promising technology for alleviating the global warming caused by the emission of CO₂. This technology, however, is still in the stage of finding efficient catalysts. The catalysts must be able to convert CO₂to other carbon‐based products with high activity and selectivity to valuable chemicals. In this review, previous development of heteroatom‐doped metal‐free carbon materials (H‐CMs) is briefly summarized. Recent progress of CO₂RR promoted by metal single‐atom catalysts (M‐SACs) is then discussed with emphasis on the synthesis of M‐SACs, the catalytic performance, and reaction mechanisms. The high temperature pyrolysis method and electrodeposition are attracting attentions recently to prepare M‐SACs with high metal loading on N‐doped carbon materials, a very active M‐SACs system for the CO₂RR. Theoretical calculations of free energy change on active sites, the Operando X‐ray absorption near edge structure (XANES), and Bader charge analysis reveal a significant role of metal oxidation state and charge transfer between metal atoms and absorbed CO. The challenges and perspectives for the extensive applications of M‐SACs in CO₂RR are also discussed in this review. 

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