Effect of Temperature and Pressure on the Kinetics of the Oxygen Reduction Reaction

Earth-abundant and inexpensive catalysts with low overpotential and high durability are central to the development of efficient water splitting electrolyzers. However, improvements in catalyst design and preparation are currently hampered by the lack of detailed understanding of the reaction mechanisms of the oxygen evolution reaction (OER) facilitated by non-precious metal (NPM) catalysts. In this manuscript, we conducted a kinetic isotope effect (KIE) study in an effort to identify the rate-determining step (RDS) of these intricate electrocatalytic reactions involving multiple proton-coupled electron transfer (PCET) processes. We observed an inverse KIE for OER catalyzed by Ni and Co electrodes. These results contribute to a more complete understanding of the OER mechanism and allow for the future development of improved NPM catalysts.

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“…3 Ω, and iR correction was 5 done following published procedures. [69][70][71] Unless otherwise stated, the scan rate was 10 mV s -1 .…”

Section: Methodsmentioning

confidence: 99%

Observation of an Inverse Kinetic Isotope Effect in Oxygen Evolution Electrochemistry

et al. 2016

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“…The mechanism of ORR has been extensively investigated in the past. 15,16,25,[17][18][19][20][21][22][23][24] It is known that platinum nanoparticles can catalyze ORR. [26][27][28] Although nanoparticles with smaller size, around 1 nm, cannot efficiently catalyze ORR due to poisoning, 29 it has been shown that Pt subnano clusters catalyze ORR at even higher rate than nanoparticles.…”

Section: Table Of Content Graphicsmentioning

confidence: 99%

Dynamics of Subnanometer Pt Clusters Can Break the Scaling Relationships in Catalysis

Zandkarimi

Alexandrova

2019

J. Phys. Chem. Lett.

112

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Scaling relationships in catalysis impose fundamental limitations on the catalyst maximal performance, and so there is a continuous hunt for ways of circumventing them. We show that, at the subnano-scale, scaling relationships can be broken through catalyst dynamics.Oxygen reduction reaction (ORR), which can be catalyzed by Pt nanoparticles, is used as our study case. Subnanometer gas phase and graphene-deposited Pt n cluster catalysts are shown to exhibit poor correlation between binding energies of intermediates, O, OH, and OOH, involved in the scaling relationships for ORR. The effect is due to the highly fluxional behavior of subnanometer clusters, which easily adapt their structures to the bound adsorbates and varying coverage, and in some cases even reshaping the structure upon changing environment. This fluxional behavior is also commonplace for clusters, and contrasts them to extended surfaces, suggesting that breaking scaling relationships is likely a rule more than an exception in nanocluster catalysis.

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“…The formation of nanoparticles and the reduction of blue silver ion using the extract of the plant was determined by the color change of the mixture to a yellow-brown (Figure 1). 19,20…”

Section: Synthesis Of Silver Nanoparticles Using T Brevifolia Extractmentioning

confidence: 99%

<p>A Potent and Safer Anticancer and Antibacterial <em>Taxus</em>-Based Green Synthesized Silver Nanoparticle</p>

Sarli¹,

Kalani²,

Moradi³

2020

IJN

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Paclitaxel is a generic drug produced based on Taxol which is an extract of Taxus tree, well known for its anticancer and antibacterial effects. This study was aimed at building up an agent with the antibacterial and anticancer benefits of both the silver ions and Taxol, together with less cytotoxic effects. Materials and Methods: Colloidal silver nanoparticles (AgNPs) were synthesized by reducing aqueous AgNO 3 with aqueous Taxus leaf extract at nonphotomediated conditions, without any catalyst, template or surfactant. The AgNP production was confirmed by ultraviolet-visible (UV-VIS) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTI) spectroscopy. The MTT assay for human breast cancer cells as well as the DAPI fluorescent staining microscopy tested the biocompatibility and anticancer effects of AgNPs, silver nitrate, and Taxol. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques were performed to determine the shape and size of the nanoparticles. MTT assay showed the best inhibitory concentration of AgNPs on cancer cells. The antibacterial activity of the three case study materials was tested for gram-positive (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) using well diffusion test. Results: This work proposes more anticancer effects for AgNP made by Taxus brevifolia extract, comparing Taxol solution. IC50 was observed as 3.1 mM for Taxol while 1.5 mM for new AgNP. Moreover, Taxus showed no antibacterial effects while the new AgNP showed a dose-dependent biocompatibility along with slightly more antibacterial effects (MIC: 1.6 and 6.6mM for gram-positive and -negative bacteria, respectively) comparing with silver nitrate solution (MIC: 1.5 and 6.2 mM for gram-positive and -negative bacteria, respectively). Conclusion:The production of herbal-mediated silver nanoparticles may be an efficient substitution for the silver nitrate-based medicines with less side effects.

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Effect of Temperature and Pressure on the Kinetics of the Oxygen Reduction Reaction

Cited by 41 publications

References 110 publications

Observation of an Inverse Kinetic Isotope Effect in Oxygen Evolution Electrochemistry

Observation of an Inverse Kinetic Isotope Effect in Oxygen Evolution Electrochemistry

Dynamics of Subnanometer Pt Clusters Can Break the Scaling Relationships in Catalysis

<p>A Potent and Safer Anticancer and Antibacterial <em>Taxus</em>-Based Green Synthesized Silver Nanoparticle</p>

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