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Abstract Vapor‐based deposition techniques are emerging approaches for the design of carbon‐supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt‐pCVD) approach is employed to deposit different Pt entities on mesoporous N‐doped carbon (MPNC) nanospheres to design high‐performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50‐250) and deposition temperature (225–300 °C) are investigated. The Pt‐pCVD process results in highly dispersed ultrasmall Pt clusters (≈1 nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC‐Pt‐pCVD electrocatalyst prepared in this work (250 pulses, 250 °C) reveals a Pt HER mass activity of 22.2 ± 1.2 A mg−1Ptat ‐50 mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 ± 2 A mg−1Ptat ‐50 mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster‐based electrocatalysts reported so far.
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Characterization of paramagnetic states in an organometallic nickel hydrogen evolution electrocatalyst
Abstract Significant progress has been made in the bioinorganic modeling of the paramagnetic states believed to be involved in the hydrogen redox chemistry catalyzed by [NiFe] hydrogenase. However, the characterization and isolation of intermediates involved in mononuclear Ni electrocatalysts which are reported to operate through a NiI/IIIcycle have largely remained elusive. Herein, we report a NiIIcomplex (NCHS2)Ni(OTf)2, where NCHS2 is 3,7-dithia-1(2,6)-pyridina-5(1,3)-benzenacyclooctaphane, that is an efficient electrocatalyst for the hydrogen evolution reaction (HER) with turnover frequencies of ~3,000 s−1and a overpotential of 670 mV in the presence of trifluoroacetic acid. This electrocatalyst follows a hitherto unobserved HER mechanism involving C-H activation, which manifests as an inverse kinetic isotope effect for the overall hydrogen evolution reaction, and NiI/NiIIIintermediates, which have been characterized by EPR spectroscopy. We further validate the possibility of the involvement of NiIIIintermediates by the independent synthesis and characterization of organometallic NiIIIcomplexes.
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- Award ID(s):
- 2155160
- PAR ID:
- 10397613
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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