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Overpotential

About: Overpotential is a research topic. Over the lifetime, 16474 publications have been published within this topic receiving 616632 citations.


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TL;DR: The results reveal that the pyridinic-N tends to be the most active N functional group to facilitate ORR at low overpotential via a four-electron pathway.
Abstract: The nitrogen-doped graphene (NG) with dominance of the pyridinic-N configuration is synthesized via a straightforward process including chemical vapor deposition (CVD) growth of graphene and postdoping with a solid nitrogen precursor of graphitic C3N4 at elevated temperature. The NG fabricated from CVD-grown graphene contains a high N content up to 6.5 at. % when postdoped at 800 °C but maintains high crystalline quality of graphene. The obtained NG exhibits high activity, long-standing stability, and outstanding crossover resistance for electrocatalysis of oxygen reduction reaction (ORR) in alkaline medium. The NG treated at 800 °C shows the best ORR performance. Further study of the dependence of ORR activity on different N functional groups in these metal-free NG electrodes provides deeper insights into the origin of ORR activity. Our results reveal that the pyridinic-N tends to be the most active N functional group to facilitate ORR at low overpotential via a four-electron pathway.

230 citations

Journal ArticleDOI
Hongxiu Zhang1, Bin Yang1, Xiaolin Wu1, Zhongjian Li1, Lecheng Lei1, Xingwang Zhang1 
TL;DR: In this article, a polymorphic CoSe2 (p-CoSe2) with mixed orthorhombic and cubic phases was obtained by calcining CoSex via electrodeposition at 300 °C.
Abstract: We report polymorphic CoSe2 (p-CoSe2) with mixed orthorhombic and cubic phases as a highly active electrocatalyst toward hydrogen evolution reaction (HER). The p-CoSe2 is obtained by calcining CoSex via electrodeposition at 300 °C. The results of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) demonstrated the crystal structure of p-CoSe2. The p-CoSe2 exhibits excellent electrocatalytic activity for HER with a low onset overpotential of −70 mV and a small Tafel slope of ∼30 mV/decade, which are basically state-of-the-art performance of earth-abundant electrocatalysts. The HER performance of p-CoSe2 was much higher than that of amorphous CoSex, cubic CoSe2, and CoSe. This study offers a competitive electrocatalyst for HER and opens up a new strategy to the synthesis of catalysts for energy conversion.

229 citations

Journal ArticleDOI
TL;DR: The synthesis of NiSe2 /CoSe2 heterostructures with different interfacial densities via an innovative strategy of successive ion injection exhibits superior electrocatalytic properties in an alkaline electrolyte, superior to other benchmarks and precious metal catalysts.
Abstract: Constructing heterostructures with abundant interfaces is essential for integrating the multiple functionalities in single entities. Herein, the synthesis of NiSe2 /CoSe2 heterostructures with different interfacial densities via an innovative strategy of successive ion injection is reported. The resulting hybrid electrocatalyst with dense heterointerfaces exhibits superior electrocatalytic properties in an alkaline electrolyte, superior to other benchmarks and precious metal catalysts. Advanced synchrotron techniques, post structural characterizations, and density functional theory (DFT) simulations reveal that the introduction of atomic-level interfaces can lower the oxidation overpotential of bimetallic Ni and Co active sites (whereas Ni2+ can be more easily activated than Co2+ ) and induce the electronic interaction between the core selenides and surface in situ generated oxides/hydroxides, which play a critical role in synergistically reducing energetic barriers and accelerating reaction kinetics for catalyzing the oxygen evolution. Hence, the heterointerface structure facilitates the catalytic performance enhancement via increasing the intrinsic reactivity of metallic atoms and enhancing the synergistic effect between the inner selenides and surface oxidation species. This work not only complements the understanding on the origins of the activity of electrocatalysts based on metal selenides, but also sheds light on further surface and interfacial engineering of advanced hybrid materials.

229 citations

Journal ArticleDOI
TL;DR: The hierarchical structure of this Co(OH)F material combines the merits of all material dimensions in heterogeneous catalysis and results in sufficient active sites per the projected electrode surface area and is favorable for efficient mass diffusion during catalysis.
Abstract: The development of new materials/structures for efficient electrocatalytic water oxidation, which is a key reaction in realizing artificial photosynthesis, is an ongoing challenge. Herein, a Co(OH)F material as a new electrocatalyst for the oxygen evolution reaction (OER) is reported. The as-prepared 3D Co(OH)F microspheres are built by 2D nanoflake building blocks, which are further woven by 1D nanorod foundations. Weaving and building the substructures (1D nanorods and 2D nanoflakes) provides high structural void porosity with sufficient interior space in the resulting 3D material. The hierarchical structure of this Co(OH)F material combines the merits of all material dimensions in heterogeneous catalysis. The anisotropic low-dimensional (1D and 2D) substructures possess the advantages of a high surface-to-volume ratio and fast charge transport. The interconnectivity of the nanorods is also beneficial for charge transport. The high-dimensional (3D) architecture results in sufficient active sites per the projected electrode surface area and is favorable for efficient mass diffusion during catalysis. A low overpotential of 313 mV is required to drive an OER current density of 10 mA cm−2 on a simple glassy carbon (GC) working electrode in a 1.0 m KOH aqueous solution.

229 citations

Journal ArticleDOI
TL;DR: A novel method for the deposition of an optically transparent amorphous iron nickel oxide oxygen evolution electrocatalyst that enables the preparation of a stable hematite/perovskite solar cell tandem device, which performs unassisted water splitting.
Abstract: Sunlight-driven water splitting to produce hydrogen fuel is an attractive method for renewable energy conversion. Tandem photoelectrochemical water splitting devices utilize two photoabsorbers to harvest the sunlight and drive the water splitting reaction. The absorption of sunlight by electrocatalysts is a severe problem for tandem water splitting devices where light needs to be transmitted through the larger bandgap component to illuminate the smaller bandgap component. Herein, we describe a novel method for the deposition of an optically transparent amorphous iron nickel oxide oxygen evolution electrocatalyst. The catalyst was deposited on both thin film and high-aspect ratio nanostructured hematite photoanodes. The low catalyst loading combined with its high activity at low overpotential results in significant improvement on the onset potential for photoelectrochemical water oxidation. This transparent catalyst further enables the preparation of a stable hematite/perovskite solar cell tandem device, which performs unassisted water splitting.

229 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20232,316
20224,268
20212,838
20202,411
20192,174
20181,740