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1. Bifunctional Ultrathin RhRu _0.5 ‐Alloy Nanowire Electrocatalysts for Hydrazine‐Assisted Water Splitting

   https://doi.org/10.1002/adma.202301533  

   Fu, Xiaoyang; Cheng, Dongfang; Wan, Chengzhang; Kumari, Simran; Zhang, Hongtu; Zhang, Ao; Huyan, Huaixun; Zhou, Jingxuan; Ren, Huaying; Wang, Sibo; et al (April 2023, Advanced Materials)

   Abstract Hydrazine‐assisted water electrolysis offers a feasible path for low‐voltage green hydrogen production. Herein, the design and synthesis of ultrathin RhRu_0.5‐alloy wavy nanowires as bifunctional electrocatalysts for both the anodic hydrazine oxidation reaction (HzOR) and the cathodic hydrogen evolution reaction (HER) is reported. It is shown that the RhRu_0.5‐alloy wavy nanowires can achieve complete electrooxidation of hydrazine with a low overpotential and high mass activity, as well as improved performance for the HER. The resulting RhRu_0.5bifunctional electrocatalysts enable, high performance hydrazine‐assisted water electrolysis delivering a current density of 100 mA cm⁻²at an ultralow cell voltage of 54 mV and a high current density of 853 mA cm⁻²at a cell voltage of 0.6 V. The RhRu_0.5 electrocatalysts further demonstrate a stable operation at a high current density of 100 mA cm⁻²for 80 hours of testing period with little irreversible degradation. The overall performance greatly exceeds that of the previously reported hydrazine‐assisted water electrolyzers, offering a pathway for efficiently converting hazardous hydrazine into molecular hydrogen. 

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2. Catalytic dinitrogen reduction to hydrazine and ammonia using Cr(N₂)₂(diphosphine)₂ complexes

   https://doi.org/10.1039/d4dt00702f  

   Beasley, Charles H; Duletski, Olivia L; Stankevich, Ksenia S; Arulsamy, Navamoney; Mock, Michael T (March 2024, Dalton Transactions)

   Cr(N₂)₂(diphosphine)₂ complexes catalyze the reduction of dinitrogen at room temperature using SmI₂ and ethylene glycol or H₂O to form hydrazine and ammonia. 

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3. Cell Microencapsulation Within Engineered Hyaluronan Elastin‐Like Protein (HELP) Hydrogels

   https://doi.org/10.1002/cpz1.917  

   Hefferon, Meghan E.; Huang, Michelle S.; Liu, Yueming; Navarro, Renato S.; de Paiva Narciso, Narelli; Zhang, Daiyao; Aviles‐Rodriguez, Giselle; Heilshorn, Sarah C. (November 2023, Current Protocols)

   Abstract Three‐dimensional cell encapsulation has rendered itself a staple in the tissue engineering field. Using recombinantly engineered, biopolymer‐based hydrogels to encapsulate cells is especially promising due to the enhanced control and tunability it affords. Here, we describe in detail the synthesis of our hyaluronan (i.e., hyaluronic acid) and elastin‐like protein (HELP) hydrogel system. In addition to validating the efficacy of our synthetic process, we also demonstrate the modularity of the HELP system. Finally, we show that cells can be encapsulated within HELP gels over a range of stiffnesses, exhibit strong viability, and respond to stiffness cues. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Elastin‐like protein modification with hydrazine Basic Protocol 2: Nuclear magnetic resonance quantification of elastin‐like protein modification with hydrazine Basic Protocol 3: Hyaluronic acid–benzaldehyde synthesis Basic Protocol 4: Nuclear magnetic resonance quantification of hyaluronic acid–benzaldehyde Basic Protocol 5: 3D cell encapsulation in hyaluronan elastin‐like protein gels 

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4. Catalytic Ammonia Oxidation to Dinitrogen by a Nickel Complex

   https://doi.org/10.1002/anie.202213462  

   Stephens, David N.; Szilagyi, Robert K.; Roehling, Paige N.; Arulsamy, Navamoney; Mock, Michael T. (November 2022, Angewandte Chemie International Edition)

   Abstract We report a nickel complex for catalytic oxidation of ammonia to dinitrogen under ambient conditions. Using the aryloxyl radical 2,4,6‐tri‐tert‐butylphenoxyl (^tBu₃ArO⋅) as a H atom acceptor to cleave the N−H bond of a coordinated NH₃ligand up to 56 equiv of N₂per Ni center can be generated. Employing theN‐oxyl radical 2,2,6,6‐(tetramethylpiperidin‐1‐yl)oxyl (TEMPO⋅) as the H‐atom acceptor, up to 15 equiv of N₂per Ni center are formed. A bridging Ni‐hydrazine product identified by isotopic nitrogen (¹⁵N) studies and supported by computational models indicates the N−N bond forming step occurs by bimetallic homocoupling of two paramagnetic [Ni]−NH₂fragments. Ni‐mediated hydrazine disproportionation to N₂and NH₃completes the catalytic cycle. 

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5. On the formation of superoxide radicals on colloidal ATiO ₃ (A = Sr and Ba) nanocrystal surfaces

   https://doi.org/10.1039/d0na00106f  

   Abdullah, Muhammad; Nelson, Ruby J.; Kittilstved, Kevin R. (May 2020, Nanoscale Advances)

   Controlling the surface chemistry of colloidal semiconductor nanocrystals is critical to exploiting their rich electronic structures for various technologies. We recently demonstrated that the hydrothermal synthesis of colloidal nanocrystals of SrTiO 3 , a technologically-relevant electronic material, provided a strong negative correlation between the presence of an O 2 -related surface defect and hydrazine hydrate [W. L. Harrigan, S. E. Michaud, K. A. Lehuta, and K. R. Kittilstved, Chem. Mater. , 2016, 28 (2), 430]. When hydrazine hydrate is omitted during the aerobic hydrothermal synthesis, the surface defect is observed. However, it can be removed by either the addition of hydrazine hydrate or by purging the reaction solution with argon gas before the hydrothermal synthesis. We also propose that the formation of the O 2 -related defect is mediated by the reduction of dissolved O 2 by lactate anions that are present from the titanium precursor. This work helps elucidate the nature of the O 2 -related defect as a superoxide anion and presents a mechanism to explain its formation during the hydrothermal synthesis of SrTiO 3 and related BaTiO 3 nanocrystals. 

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