Stabilization of a Highly Concentrated Colloidal Suspension of Pristine Metallic Nanoparticles

Katiyar, Nirmal Kumar; Biswas, Krishanu; Tiwary, Chandra Sekhar; Machado, Leonardo D.; Gupta, Raju Kumar

doi:10.1021/acs.langmuir.8b03401

“…Thus the more positively charged NiO‐NPs in the presence of a small number of negatively charged hydroxide groups are likely to be stabilized by repulsive electrostatic double‐layer force, in spite of the absence of OLA in the mixture solvent. [ 32 ]…”

Section: Resultsmentioning

confidence: 99%

Tailoring of Ligand‐Off Nanoparticles Inks for Thin p‐Type Oxide Overlayers Formation with Maintaining Intact Halide Perovskite

Park

¹

,

Kim

²

,

Lee

³

et al. 2021

Adv Funct Materials

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In n‐i‐p halide perovskite solar cells (HPSCs), the development of p‐type oxides is one of the most noteworthy approaches as hole transport materials (HTMs) for long‐term stability and mass production. However, the deposition of oxide HTMs through a solution process over the perovskite layer without damage to the perovskite layer remains a major challenge. Here, the colloidal dispersion of ligand‐off NiO nanoparticles (NPs) to form the HTM overlayer on perovskite using appropriate solvents that do not damage the underlying perovskite layer is reported. Monodispersed NiO NPs are synthesized using oleylamine (OLA) ligands via the solvothermal method, and the OLA ligands are then removed to form ligand‐off NiO NPs. Based on the Hansen solubility theory, appropriate mixed solvents are found for both the dispersion of NiO NPs without ligands and coating without perovskite damage. The colloidal dispersion form a compact and uniform NiO NPs layer of 30 nm thickness on the perovskite layer, allowing n‐SnO2/Halide/p‐NiO HPSCs to be successfully fabricated. The HPSC shows a record power conversion efficiency under one sun illumination for an n‐i‐p oxide/halide/oxide structure and excellent thermal stability maintaining 98% of the initial efficiency for 580 h under 85 °C and 10% relative humidity condition.

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“…The high entropy alloy materials are mostly prepared by vacuum arc melting, which is an easy and scalable process for retaining the purity or decided stoichiometric proportion of metallic elements. Further, the preparation of nanocrystalline HEA utilizing mechanical milling at extremely low temperatures makes it an easy, cost-effective technique because extremely low temperature accelerates the fracture process, and also the nanoparticles are in the form of pure virgin surface, which is highly desirable for catalytic activity [29][30][31] . The nanocrystalline FeCoNiZnGa crystallographic phase has been estimated using an X-ray diffraction pattern, and it is face-centered cubic (FCC), as shown in Figure 1a X-ray photoelectron spectroscopy (XPS) is an important tool used for surface analysis to obtain the chemical states of the elements 32 .…”

Section: Resultsmentioning

confidence: 99%

Low Cost, Easy Scalable High Entropy Alloy (HEA) FeCoNiZnGa for High-Efficiency Oxygen Evolution Reaction (OER)

Sharma¹,

Kumar²,

R³

et al. 2020

Preprint

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2

0

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Oxygen evolution reaction (OER) is the key step involved both in water splitting devices as well as in rechargeable metal-air batteries and there is an urgent requirement for a highly stable and low-cost material for efficient OER. In this article, for the first time, electrocatalyst based on high entropy alloy (HEA) of FeCoNiZnGa has been reported for OER. Nano-crystalline high entropy alloys materials withdrew the attention of the research academia due to their emerging unique properties due to the cocktail effect and synergetic effect between the constituent elements. The existing materials (IrO2, RuO2, etc.) being utilized in the OER reaction contain precious metals. Thus, high entropy alloy made up of low-cost elements has been formulated and tested for the OER, which is found to be highly stable and more efficient. The formulation of nanocrystalline HEA (FeCoNiZnGa) utilized a unique recipe casting-cum-comminution (CCC). After electrochemical CV activation, transition metal oxides formation at the HEA surface helps in OER activities. HEA exhibits a low overpotential of 370 mV to achieve a current density of 10 mA cm-2 with a very small Tafel slope of 71 mV dec-1 and exceptional long term stability of electrolysis for over 10 h in 1 M KOH alkaline solution, which is extremely stable in comparison to the state-of-the-art OER electrocatalyst RuO2. Transmission electron microscopic (TEM) studies after 10 h of long term chronoamperometry testing confirmed high stability of HEA as no change in the crystal structure observed. Our work highlights the great potential of HEA towards oxygen evolution reaction which is primary reaction involved in water splitting.

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“…The high entropy alloy materials are mostly prepared by vacuum arc melting, which is an easy and scalable process for retaining the purity or decided stoichiometric proportion of metallic elements. Further, the preparation of nanocrystalline HEA utilizing mechanical milling at extremely low temperatures makes it an easy, cost-effective technique because extremely low temperature accelerates the fracture process, and also the nanoparticles are in the form of pure virgin surface, which is highly desirable for catalytic activity [29][30][31] . The nanocrystalline FeCoNiZnGa crystallographic phase has been estimated using an X-ray diffraction pattern, and it is face-centered cubic (FCC), as shown in Figure 1a.…”

Section: Resultsmentioning

confidence: 99%

Low Cost, Easy Scalable High Entropy Alloy (HEA) FeCoNiZnGa for High-Efficiency Oxygen Evolution Reaction (OER)

Sharma¹,

Kumar²,

Das³

et al. 2020

Preprint

Self Cite

1

0

View full text Add to dashboard Cite

Oxygen evolution reaction (OER) is the key step involved both in water splitting devices as well as in rechargeable metal-air batteries and there is an urgent requirement for a highly stable and low-cost material for efficient OER. In this article, for the first time, electrocatalyst based on high entropy alloy (HEA) of FeCoNiZnGa has been reported for OER. Nano-crystalline high entropy alloys materials withdrew the attention of the research academia due to their emerging unique properties due to the cocktail effect and synergetic effect between the constituent elements. The existing materials (IrO2, RuO2, etc.) being utilized in the OER reaction contain precious metals. Thus, high entropy alloy made up of low-cost elements has been formulated and tested for the OER, which is found to be highly stable and more efficient. The formulation of nanocrystalline HEA (FeCoNiZnGa) utilized a unique recipe casting-cum-comminution (CCC). After electrochemical CV activation, transition metal oxides formation at the HEA surface helps in OER activities. HEA exhibits a low overpotential of 370 mV to achieve a current density of 10 mA cm-2 with a very small Tafel slope of 71 mV dec-1 and exceptional long term stability of electrolysis for over 10 h in 1 M KOH alkaline solution, which is extremely stable in comparison to the state-of-the-art OER electrocatalyst RuO2. Transmission electron microscopic (TEM) studies after 10 h of long term chronoamperometry testing confirmed high stability of HEA as no change in the crystal structure observed. Our work highlights the great potential of HEA towards oxygen evolution reaction which is primary reaction involved in water splitting.

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Stabilization of a Highly Concentrated Colloidal Suspension of Pristine Metallic Nanoparticles

Cited by 25 publications

References 38 publications

Tailoring of Ligand‐Off Nanoparticles Inks for Thin p‐Type Oxide Overlayers Formation with Maintaining Intact Halide Perovskite

Tailoring of Ligand‐Off Nanoparticles Inks for Thin p‐Type Oxide Overlayers Formation with Maintaining Intact Halide Perovskite

Low Cost, Easy Scalable High Entropy Alloy (HEA) FeCoNiZnGa for High-Efficiency Oxygen Evolution Reaction (OER)

Low Cost, Easy Scalable High Entropy Alloy (HEA) FeCoNiZnGa for High-Efficiency Oxygen Evolution Reaction (OER)

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