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1. Unprecedented Multifunctionality in 1D Nb _{1‐ x} Ta _x S ₃ Transition Metal Trichalcogenide Alloy

   https://doi.org/10.1002/adfm.202205214  

   Hemmat, Zahra; Ahmadiparidari, Alireza; Wang, Shuxi; Kumar, Khagesh; Zepeda, Michael; Zhang, Chengji; Dandu, Naveen; Rastegar, Sina; Majidi, Leily; Jaradat, Ahmad; et al (June 2022, Advanced Functional Materials)

   Abstract 1D materials, such as nanofibers or nanoribbons are considered as the future ultimate limit of downscaling for modern electrical and electrochemical devices. Here, for the first time, nanofibers of a solid solution transition metal trichalcogenide (TMTC), Nb_1‐xTa_xS₃, are successfully synthesized with outstanding electrical, thermal, and electrochemical characteristics rivaling the performance of the‐state‐of‐the art materials for each application. This material shows nearly unchanged sheet resistance (≈740 Ω sq⁻¹) versus bending cycles tested up to 90 cycles, stable sheet resistance in ambient conditions tested up to 60 days, remarkably high electrical breakdown current density of ≈30 MA cm⁻², strong evidence of successive charge density wave transitions, and outstanding thermal stability up to ≈800 K. Additionally, this material demonstrates excellent activity and selectivity for CO₂conversion to CO reaching ≈350 mA cm⁻²at −0.8 V versus RHE with a turnover frequency number of 25. It also exhibits an excellent performance in a high‐rate Li–air battery with the specific capacity of 3000 mAh g⁻¹at a current density of 0.3 mA cm⁻². This study uncovers the multifunctionality in 1D TMTC alloys for a wide range of applications and opens a new direction for the design of the next generation low‐dimensional materials. 

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2. Enhancing CO ₂ Reduction Efficiency on Cobalt Phthalocyanine via Axial Ligation

   https://doi.org/10.1002/cctc.202300576  

   Kang, Hongxing; Staples‐West, Aaliyah; Washington, Audrey; Turchiano, Chris; Cooksy, Andrew; Huang, Jier; Gu, Jing (June 2023, ChemCatChem)

   Abstract Electrochemical reduction of carbon dioxide (CO₂RR) to value‐added products is a promising strategy to alleviate the greenhouse gas effect. Molecular catalysts, such as cobalt (II) phthalocyanine (CoPc), are known to be efficient electrocatalysts that are capable of converting CO₂into carbon monoxide (CO). Herein, we report an axial modification strategy to enhance CoPc's CO₂RR performance. After coordinating with axial ligands, the electron density of Co was depleted via π‐backbonding. This π‐backbonding weakened the Co‐CO bond, resulting in rapid desorption of CO. Also, the presence axial ligands elevated the Co dz²orbital energy, resulting in a significantly enhanced CO selectivity, evidenced by an increased faradaic efficiency (FE) from 82 % (CoPc) to 91 % and 94 % with the presence of pyridine (CoPc‐py) and imidizal ligands (CoPc‐im), respectively, at −0.82 V vs. RHE. Density functional theory calculations reveal that axial ligation of CoPc can reduce the energy barrier for CO₂activation and facilitate the formation of^*COOH. 

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3. Non‐Aqueous Electrochemical CO ₂ Reduction to Multivariate C ₂ ‐Products Over Single Atom Catalyst at Current Density up to 100 mA cm ⁻²

   https://doi.org/10.1002/smll.202408010  

   Bhawnani, Rajan_R; Sartape, Rohan; Gande, Vamsi_V; Barsoum, Michael_L; Kallon, Elias_M; Reis, Roberto_dos; Dravid, Vinayak_P; Singh, Meenesh_R (December 2024, Small)

   Abstract Electrochemical CO₂reduction reaction (CO₂‐RR) in non‐aqueous electrolytes offers significant advantages over aqueous systems, as it boosts CO₂solubility and limits the formation of HCO₃⁻and CO₃²⁻anions. Metal–organic frameworks (MOFs) in non‐aqueous CO₂‐RR makes an attractive system for CO₂capture and conversion. However, the predominantly organic composition of MOFs limits their electrical conductivity and stability in electrocatalysis, where they suffer from electrolytic decomposition. In this work, electrically conductive and stable Zirconium (Zr)‐based porphyrin MOF, specifically PCN‐222, metalated with a single‐atom Cu has been explored, which serves as an efficient single‐atom catalyst (SAC) for CO₂‐RR. PCN‐ 222(Cu) demonstrates a substantial enhancement in redox activity due to the synergistic effect of the Zr matrix and the single‐atom Cu site, facilitating complete reduction of C₂species under non‐aqueous electrolytic conditions. The current densities achieved (≈100 mA cm⁻²) are 4–5 times higher than previously reported values for MOFs, with a faradaic efficiency of up to 40% for acetate production, along with other multivariate C₂products, which have never been achieved previously in non‐aqueous systems. Characterization using X‐ray and various spectroscopic techniques, reveals critical insights into the role of the Zr matrix and Cu sites in CO₂reduction, benchmarking PCN‐222(Cu) for MOF‐based SAC electrocatalysis. 

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4. 2D Copper Tetrahydroxyquinone Conductive Metal–Organic Framework for Selective CO ₂ Electrocatalysis at Low Overpotentials

   https://doi.org/10.1002/adma.202004393  

   Majidi, Leily; Ahmadiparidari, Alireza; Shan, Nannan; Misal, Saurabh_N; Kumar, Khagesh; Huang, Zhehao; Rastegar, Sina; Hemmat, Zahra; Zou, Xiaodong; Zapol, Peter; et al (February 2021, Advanced Materials)

   Abstract Metal–organic frameworks (MOFs) are promising materials for electrocatalysis; however, lack of electrical conductivity in the majority of existing MOFs limits their effective utilization in the field. Herein, an excellent catalytic activity of a 2D copper (Cu)‐based conductive MOF, copper tetrahydroxyquinone (CuTHQ), is reported for aqueous CO₂reduction reaction (CO₂RR) at low overpotentials. It is revealed that CuTHQ nanoflakes (NFs) with an average lateral size of 140 nm exhibit a negligible overpotential of 16 mV for the activation of this reaction, a high current density of ≈173 mA cm⁻²at −0.45 V versus RHE, an average Faradaic efficiency (F.E.) of ≈91% toward CO production, and a remarkable turnover frequency as high as ≈20.82 s⁻¹. In the low overpotential range, the obtained CO formation current density is more than 35 and 25 times higher compared to state‐of‐the‐art MOF and MOF‐derived catalysts, respectively. The operando Cu K‐edge X‐ray absorption near edge spectroscopy and density functional theory calculations reveal the existence of reduced Cu (Cu⁺) during CO₂RR which reversibly returns to Cu²⁺after the reaction. The outstanding CO₂catalytic functionality of conductive MOFs (c‐MOFs) can open a way toward high‐energy‐density electrochemical systems. 

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5. Enhanced Electrochemical Performance of LiNi _0.8 Co _0.1 Mn _0.1 O ₂ with SiO ₂ Surface Coating Via Homogeneous Precipitation

   https://doi.org/10.1002/celc.202101230  

   Dou, Lintao; Hu, Pu; Shang, Chaoqun; Wang, Heng; Xiao, Dongdong; Ahuja, Utkarsh; Aifantis, Katerina; Zhang, Zhanhui; Huang, Zhiliang (November 2021, ChemElectroChem)

   Abstract Ni‐rich LiNi_0.8Co_0.1Mn_0.1O₂(NCM811) has been considered as a promising cathode material for high energy density lithium‐ion batteries. However, it experiences undesirable interfacial side‐reactions with the electrolyte, which lead to a rapid capacity decay. In this work, a homogeneous precipitation method is proposed for forming a uniform silicon dioxide (SiO₂) coating on the NCM811 surface. The strong Si−O network provided a stable protective layer between the NCM811 active material and electrolyte to improve the electrochemical stability. As a result, the NCM811@SiO₂cathode showed superior cycling stability (84.9 % after 100 cycles at 0.2 C) and rate capability (142.7 mA h g⁻¹at 5 C) compared to the pristine NCM811 cathode (56.6 % after 100 cycles, 127.9 mA h g⁻¹at 5 C). Moreover, the SiO₂coating effectively suppressed voltage decay and pulverization of the NCM811 particles during long term cycling. This uniform coating technique offers a viable approach for stabilizing Ni‐rich cathode materials for high‐energy density lithium‐ion batteries. 

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