The future of affordable fuel cells strongly relies on the design of earth-abundant (non-platinum) catalysts for the electrochemical oxygen reduction reaction (ORR). However, the bottleneck in the overall process occurs therein. We have examined herein trivalent Mn, Fe, Co, Ni, and Cu complexes of β-pyrrole-brominated corrole as ORR catalysts. The adsorption of these complexes on a high-surface-area carbon powder (BP2000) created a unique composite material, used for electrochemical measurements in acidic aqueous solutions. These experiments disclosed a clear dependence of the catalytic activity on the metal center of the complexes, in the order of Co>Fe>Ni>Mn>Cu. The best catalytic performance was obtained for the Co(III) corrole, whose onset potential was as positive as 0.81 V versus the reversible hydrogen electrode (RHE). Insight into the properties of these systems was gained by spectroscopic and computational characterization of the reduced and oxidized forms of the metallocorroles.
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Sci Rep
December 2024
School of Environmental Science, The University of Shiga Prefecture, Hassakacho, Hikone, 2500, 522-8533, Japan.
Mangrove forests are increasingly recognized as vital blue carbon ecosystems due to their high carbon sequestration capacity, primarily through the accumulation of soil organic carbon (SOC). Recent research highlights that, in addition to SOC, dissolved inorganic carbon (DIC), particularly in the form of bicarbonate (HCO₃⁻), plays a crucial role in carbon sequestration by being exported from these ecosystems to adjacent coastal waters. This study aims to investigate the previously unexamined mechanisms behind bicarbonate production in mangrove soils.
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December 2024
Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
Polymer electrolyte membrane water electrolyzers (PEMWEs) are a critical technology for efficient hydrogen production to decarbonize fuels and industrial feedstocks. To make hydrogen cost-effective, the overpotentials across the cell need to be decreased and platinum-group metal loading reduced. One overpotential that needs to be better understood is due to mass transport limitations from bubble formation within the porous transport layer (PTL) and anode catalyst layer (ACL), which can lead to a reduction in performance at typical operating current densities.
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December 2024
Key Laboratory of Molecular Nanostructure and Nanotechnology, Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
Zn-air batteries (ZABs) present high energy density and high safety but suffer from low oxygen reaction reversibility and dendrite growth at Zn electrode in alkaline electrolytes. Non-alkaline electrolytes have been considered recently for improving the interfacial processes in ZABs. However, the dynamic evolution and reaction mechanisms regulated by electrolytes at both the positive and Zn negative electrodes remain elusive.
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December 2024
Department of Chemistry, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea.
Oxidative modifications can disrupt protein folds and functions, and are strongly associated with human aging and diseases. Conventional oxidation pathways typically involve the free diffusion of reactive oxygen species (ROS), which primarily attack the protein surface. Yet, it remains unclear whether and how internal protein folds capable of trapping oxygen (O) contribute to oxidative damage.
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December 2024
Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou, China.
Natural enzymes feature distinctive second spheres near their active sites, leading to exquisite catalytic reactivity. However, incumbent synthetic strategies offer limited versatility in functionalizing the second spheres of heterogeneous catalysts. Here, we prepare an enzyme-mimetic single Co-N atom catalyst with an elaborately configured pendant amine group in the second sphere via 1,3-dipolar cycloaddition, which switches the oxygen reduction reaction selectivity from the 4e to the 2e pathway under acidic conditions.
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