Novel continuous flow synthesis of Pt NPs with narrow size distribution for Pt@carbon catalysts

Singh, Ankit; Miyabayashi, Keiko

doi:10.1039/c9ra08762a

Cited by 20 publications

(12 citation statements)

References 32 publications

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“…Similar studies have also been carried out on Co–N–C/900 (Figure S32b), revealing the identical features. Contrary to that, Figure S32c,d represents the Pt 4f HRXPS spectra for commercial Pt/C, which confirms the structural changes observed during the ORR process as compared to that of the Co–N x -based system.…”

Section: Resultsmentioning

confidence: 99%

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Rational Designing of Co–N–C Electrocatalysts for Comprehensive Elucidation of Intrinsic and Extrinsic Activities in the Oxygen Reduction Reaction

Bisen

Nandan

Raj

et al. 2022

ACS Appl. Energy Mater.

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The catalytic efficacy of an electrocatalyst is mostly apprised by the intrinsic activity of individual active sites and/or by extrinsic activity, which is dependent on the active site density. In oxygen electrochemistry, extrinsic activity can influence the concomitant current density, while intrinsic activity can potentially influence the onset potential, exchange current density, and half-wave potential besides the current density. Modulation of intrinsic activity is mostly limited as it is mainly dependent on the electronic and chemical structure of active sites. The extrinsic activity can be improved by employing the post-synthesis modifications without disturbing the inherent catalytic nature (i.e., intrinsic activity) of individual active sites to ensure the utility of maximum instituted centers. In this work, we have made an attempt to elucidate the intrinsic and extrinsic activities of Co–N–C-based nanostructures to promote the oxygen reduction reaction (ORR) efficiency, which is further elucidated by X-ray absorption spectroscopic studies. The experimental finding suggests that an increase in the N content (∼9 at %) in the host medium, that is, carbon, decisively impacts the intrinsic nature of electrocatalysts with a positive shift in the ORR onset potential of ∼ 131 mV and a nearly 1.5-fold increase in the exchange current density, a matrix that gives a measure of the ability to support catalytic activity inherently. The targeted removal of electrochemically less effective Co nanoparticles (which block/obscure the active centers Co–N x in their vicinity) ensures the structural intactness as the C 1s full width at half maximum of the host matrix along with ORR onset potentials and Tafel slopes remains unchanged. The experimental finding further indicates that the current density can be improved by a factor of 2.6 (i.e., from 2.13 to 5.65 mA/cm2), ensuring the effective utilization of electrocatalysts. Overall, the rational combination of intrinsic and extrinsic activities can be valuable to design a variety of transition metal-carbon based electrocatalysts for diverse electrochemical energy devices.

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Section: Resultsmentioning

confidence: 99%

“…Similar studies have also been carried out on Co−N−C/900 (Figure S32b), revealing the identical features. Contrary to that, Figure S32c,d represents the Pt 4f HRXPS spectra for commercial Pt/C,78…”

mentioning

confidence: 98%

Rational Designing of Co–N–C Electrocatalysts for Comprehensive Elucidation of Intrinsic and Extrinsic Activities in the Oxygen Reduction Reaction

Bisen

Nandan

Raj

et al. 2022

ACS Appl. Energy Mater.

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“…Another major drawback to date in surfactant-free syntheses is the need for high-boiling-point and viscous solvents (e.g., DMC or polyols) requiring intensive washing steps and/or high temperature to perform the synthesis. In particular, flow systems are envisioned as a key component of the large-scale production of nanomaterials . Low-viscosity solvents such as monoalcohols are promising candidates in order to avoid high-pressure systems .…”

Section: Discussionmentioning

confidence: 99%

Surfactant-Free Colloidal Syntheses of Precious Metal Nanoparticles for Improved Catalysts

2023

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Colloidal syntheses of nanomaterials offer multiple benefits to study, understand, and optimize unsupported and supported catalysts. In particular, colloidal syntheses are relevant to the synthesis of (precious) metal nanoparticles. By separating the synthesis of the active phase, i.e., the nanoparticles, from supporting steps, a deeper knowledge and rational control of the properties of supported catalysts is gained. The effect(s) of the size, shape, and composition of the nanoparticle, the nature of the support, or the metal loading on a support can be studied in more systematic ways. The fundamental knowledge gained paves the way for catalyst optimization by tuning the catalyst activity, selectivity, and stability. However, most colloidal syntheses require the use of additives or surfactants, which are detrimental to most catalytic reactions because they typically block catalyst active sites. Surfactant removal is therefore often required, which adds complexity to the synthesis and the analysis of the obtained results. Developing surfactant-free strategies to obtain stable colloidal nanoparticles is therefore a rising field of research that is here reviewed. A focus is given to laser synthesis and processing of colloids-, solution plasma process-, N,N-dimethylformamide-, polyol-, and recently reported monoalcohol-based syntheses. The relevance of these synthetic approaches for catalysis is detailed with a focus on heterogeneous catalysis and electrocatalysis.

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“…In particular flow systems are envisioned as a key component of the production of large scale production of nanomaterials. 280 Low viscosity solvents such as mono-alcohols are promising candidate in order to avoid high pressure systems. 275 In light of these considerations, it is anticipated that surfactantfree mono-alcohols syntheses will play an increasing role not only for fundamental but also applied research.…”

Section: Comparisonmentioning

confidence: 99%

Surfactant-free colloidal syntheses of precious metal nanoparticles for improved catalysts

Quinson

Kunz²,

Arenz

2022

Preprint

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Colloidal syntheses of nanomaterials offer multiple benefits to study, understand and optimize un-supported and supported catalysts. In particular, colloidal syntheses are relevant to synthetize (precious) metal nanoparticles. By separating the synthesis of the active phase nanoparticles from supporting steps, a deeper knowledge and a rational control on supported catalyst properties is gained. The effect of nanoparticle size, shape, composition, nature of support or metal loading on a support can be studied in more systematic ways. The fundamental knowledge gained paves the way for catalyst optimization by tuning the catalyst activity, selectivity, and stability. However, a major drawback is that most colloidal syntheses require the use of additives or surfactants, which are detrimental to most catalytic reactions since they typically block catalyst active sites. Surfactant removal typically adds complexity, can introduce a lack of reproducibility, is energy consuming, generates waste, and prevents the full exploitation of the many benefits of colloidal syntheses for catalysis. Several surfactant-free strategies to obtain stable colloidal nanoparticles are here reviewed. A focus is given to laser synthesis and processing of colloids (LSPC), solution plasma process (SPP), N,N-dimethylformamide (DMF), polyols, and recently reported mono-alcohols based syntheses. The relevance of these synthetic approaches for catalysis is detailed with a focus on heterogeneous catalysis and electro-catalysis.

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Novel continuous flow synthesis of Pt NPs with narrow size distribution for Pt@carbon catalysts

Abstract: A novel continuous flow synthesis method was performed to achieve ultra-small Pt NPs (2.3 to 2.5 nm) with narrow size distribution. This method expedites the synthesis of Pt NPs without any harsh reducing agent or capping agent.

Cited by 20 publications

References 32 publications

Rational Designing of Co–N–C Electrocatalysts for Comprehensive Elucidation of Intrinsic and Extrinsic Activities in the Oxygen Reduction Reaction

Rational Designing of Co–N–C Electrocatalysts for Comprehensive Elucidation of Intrinsic and Extrinsic Activities in the Oxygen Reduction Reaction

Surfactant-Free Colloidal Syntheses of Precious Metal Nanoparticles for Improved Catalysts

Surfactant-free colloidal syntheses of precious metal nanoparticles for improved catalysts

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