The escalating demand and dwindling reserves of precious metals request efficient recycling techniques from electron waste. Addressing this need, we introduce a new method utilizing tannin-grafted mesoporous silica for the sunlight-boosted recovery of precious metals. Our strategy leverages the inherent photoreactivity of tannins, enabling metal–ligand complexation and plasmonic enhancement of chemical reduction. The result is a marked increase in the adsorption capacity and the high selectivity towards precious metal ions in electronic waste. Our robust covalent bonding approach concentrated tannic acids onto silica at a high density (500,000 per square micrometer), which significantly boosted the adsorption of gold ions up to an 11-fold increase, even amidst a mixture of nine other metal species. Impressively, we achieved a maximum adsorption capacity of 68.4 mmol per gram, equivalent to 13.4 g of gold per gram of adsorbent. Also, the adsorption rates for platinum and palladium ions were enhanced by 2.6 and 3.0 times, respectively. The underlying mechanism includes the visible-light-driven plasmonic hot electron transfer that affords nearly perfect selectivity for gold ions (approximately 99%). These findings not only advance the field of metal recovery from electronic waste but also offer an environmentally benign and cost-effective solution that harnesses renewable solar energy.
Sustainable Gas Storage: CO2 Activation of Edge-Functionalized Graphitic Nanoplatelets
Seok-Jin Kim, Min Hui Kim, Se Jung Lee, Cafer T. Yavuz, In-Yup Jeon
Graphitic nanoplatelets (GnPs), edge-selectively carboxylated graphitic nanoplatelets (ECGnPs), are functionalized with a carboxylic acid at the edge increasing their surface area, and are highly dispersible in various solvents. However, there is a limit in that the basal plane remains intact because it is functionalized only in the part where the radical is generated at the edge. Here, we activate ECGnPs to have porous structures by flowing CO2 at 900 °C. Etching of the ECGnPs structure was performed through the Boudouard reaction, and the surface area increased from 579 m2 g−1 to a maximum of 2462 m2 g−1. In addition, the pore structure was investigated with various adsorption gases (CH4, Ar, CO2, H2, and N2) according to the reaction time. This study provides the overall green chemistry in that it utilizes CO2 from manufacturing to activation compared to the process of activating with conventional chemical treatment.
Scalable Design of Ru-Embedded Carbon Fabric Using Conventional Carbon Fiber Processing for Robust Electrocatalysts
Seok-Jin Kim, Ga-Hyeun Lee, Jung-Eun Lee, Javeed Mahmood, Gao-Feng Han, Inkyung Baek, Changbeom Jeon, Minjung HanHwakyung Jeong, Cafer T. Yavuz*, Han Gi Chae*, Jong-Beom Baek*
Journal of the American Chemical Society, 146, 13142-13150
Metal–carbon composites are extensively utilized as electrochemical catalysts but face critical challenges in mass production and stability. We report a scalable manufacturing process for ruthenium surface-embedded fabric electrocatalysts (Ru-SFECs) via conventional fiber/fabric manufacturing. Ru-SFECs have excellent catalytic activity and stability toward the hydrogen evolution reaction, exhibiting a low overpotential of 11.9 mV at a current density of 10 mA cm–2 in an alkaline solution (1.0 M aq KOH solution) with only a slight overpotential increment (6.5%) after 10,000 cycles, whereas under identical conditions, that of commercial Pt/C increases 6-fold (from 1.3 to 7.8 mV). Using semipilot-scale equipment, a protocol is optimized for fabricating continuous self-supported electrocatalytic electrodes. Tailoring the fiber processing parameters (tension and temperature) can optimize the structural development, thereby achieving good catalytic performance and mechanical integrity. These findings underscore the significance of self-supporting catalysts, offering a general framework for stable, binder-free electrocatalytic electrode design.
Engineering Single-Atom Catalysts on Conjugated Porphyrin Polymer Photocatalysts via E-Waste for Sustainable Photocatalysis
Bolormaa Bayarkhuu, Hyekyung Cho, Gaeun Cho, Jeeho Hong, Yeongran Hong, Se-Woong Baek, Sungeun Yang, Cafer T. Yavuz, Han Seul Kim, Jeehye Byun
This study presents a surface engineering strategy utilizing electronic waste (e-waste) to incorporate single-atom catalysts on conjugated polymers. Employing a conjugated porphyrin polymeric photocatalyst, gold single-atom-site catalysts are successfully introduced using the acidic metal leachates from e-waste, where metal speciation and composition are regulated during the metal loading processes. The resulting photocatalyst with gold single atoms demonstrates a remarkable hydrogen peroxide (H2O2) selectivity of up to 97.56%, yielding a pure H2O2 solution at 73.3 µm h−1 under white LED illumination. The produced H2O2 is activated to •OH radicals on the same polymer with mixed gold and iron atoms, enabling a photo-Fenton reaction and the complete degradation of toxic microcystin-LR within 10 min under visible light. This study highlights the universal applicability of the metal mining strategy in various photoreactions. It is believed that this discovery pioneers sustainable photocatalysis, allowing the tuning of reactivity and selectivity on photocatalytic surfaces using metal waste.
Solvent-Induced Reversible Guest Uptake and Release by Flexible Porous Organic Cages
Abdul Ghaffar, Muhammad Bilal Asif, Javeed Mahmood, Cafer T. Yavuz
Porous organic cages with intrinsic and extrinsic cavities offer excellent host–guest control, molecular uptake, and on-demand release without compromising the selectivity. However, dynamic control over the porosity in cage molecules remains challenging. Herein, we report a CC3 cage-based crystalline adsorbent with dynamic control over its porosity for stable adsorption and release of the probe organic molecules. Interestingly, the polymorphic forms of cages (α and β) differ in crystallographic packing with flexible orientation but retain their structure after solvation. Using this isomorphism, the CC3 adsorbent exhibited an uptake of 29.5 mg g–1 for neutral red, 39.5 mg g–1 for methyl blue, and 39 mg g–1 for both molecules. The solvent-induced phase transition selectively obstructs neutral red adsorption with 85.5% change in overall capacity. Adsorption affinity correlates strongly with surface area, while solvent choice governs selectivity, highlighting switchable porosity. These findings enable advanced adsorbents with switchable porosity and selective affinity for energy and environmental applications.
Scalable synthesis of Sb-doped Rb3InCl6 nanocrystals for high-resolution X-ray imaging screen
Azimet A. Karluk, Saidkhozha Nematulloev, Simil Thomas, Bashir E. Hasanov, Khursand Yorov, Rounak Naphade, Luis Gutie´rrez-Arzaluz, Bodiuzzaman Mohammad, Mutalifu Abulikemu, Javeed Mahmood, and Cafer T. Yavuz
Lead-free, all-inorganic halide nanocrystals hold promise for advanced devices, with chloride-based variants offering stability, tunable band gaps, and easy processing. However, these nanocrystals face synthesis challenges due to the low solubility and complex coordination of heavy metal chloride salts. The conventional ligand-assisted reprecipitation (LARP) method is incompatible with chloride-based crystals, while the hot-injection technique is slow and complex, hindering efficient synthesis and scalability. We present a modified LARP method using an acid-mediated strategy to synthesize undoped and Sb3+-doped Rb3InCl6 nanocrystals. These nanocrystals maintain colloidal stability for up to 6 months and exhibit a large Stokes shift (230 nm), a high photoluminescence quantum yield (PLQY) of 68.01%, low self-absorption, and a high light yield of 15,500 photons/MeV. The flexible nanocrystal composite film with polysulfone achieves an X-ray imaging resolution of 18.5 line pairs per millimeter (lp mm−1). The colloidal solution and film of Rb3InCl6:Sb nanocrystals exhibit strong radioluminescence and linear responses under X-ray irradiation, highlighting their potential for medical radiography.
Catalysts for dry reforming and methods of producing the same
US20240050933A1
Cafer Tayyar Yavuz, Seokjin Kim, Aadesh Harale, Bandar Al-Solami, Aqil Jamal
The disclosure relates to catalysts for dry reforming, methods of producing the catalysts, and methods of using the catalysts in dry reforming. The catalysts contain nickel, molybdenum and a metal oxide. The methods of producing the catalysts include adding a solvent to precipitate the catalyst, followed by removing the solvent. The solvent addition and removal steps can be repeated as desired.
Solvent-linked porous covalent organic polymers and method of preparing the same
US Patent 11,535,701,2022
Cafer T Yavuz, Vepa Rozyyev, Joo Sung Lee
Solvent-linked porous covalent organic polymers (COPs) and a method of preparing the same are described. The porous covalent organic polymers are linked by a solvent and are thus suitable for the transportation and storage of natural gas. A method of preparing the porous covalent organic polymers by conducting alkylation polymerization between an aromatic monomer and a chlorine-based solvent in the presence of a Lewis acid catalyst is described. Porous stretchable covalent organic polymers having pores with various sizes can be synthesized simply and quickly at room temperature and atmospheric pressure without a heating or purification step. The covalent organic polymers have very high natural gas storage capacity due to the flexible porous network structure thereof and thus are suitable for storage and transportation of natural gas and useful as a natural gas adsorbent.
Electroless plating solution and electroless plating method for recovering precious metal adsorbed on porous porphyrin polymer
US Patent App. 17/413,559, 2022
Jong-In Han, SON JiEun, Cafer Yavuz, HONG Youngran
The present invention relates to a method for recovering a precious metal selectively adsorbed on a porous porphyrin polymer, and to an electroless plating method capable of recovering a precious metal in a film form by desorbing and leaching the precious metal without an additional oxidizing agent and using same as a plating solution to reduce the precious metal on the surface of a substrate without an additional reducing agent.
The electrochemical plating apparatus for recovering a noble metal adsorbed to the porous polymeric porphyrin
App # 10-2018-0162180, 2018.
C. T. Yavuz, Y. Hong
The present invention relates to an apparatus and a method of electrochemical plating for recovering precious metals adsorbed on a porous porphyrin polymer, wherein precious metals selectively adsorbed on a porous porphyrin polymer is leached into an electrolyte to be collected in a film shape on a surface of a reducing electrode through electrochemical reduction reaction.COPYRIGHT KIPO 2020
Natural gas storage utilizing the elastic organic polymer covalent bond which is connected to the solvent
App # 10-2019-0058296, 2019.
C. T. Yavuz, V. Rozyyev
The present invention relates to solvent linked porous covalent organic polymers and a method for preparing the same. More particularly, the present invention relates to porous covalent organic polymers linked by a solvent, thereby being suitable for transport and storage of natural gas, and to a method for preparing the porous covalent organic polymers by adding an aromatic monomer and a chlorine-based solvent in the presence of a Lewis acid catalyst, followed by alkylation. Under the conditions of room temperature and room pressure, it is possible to synthesize porous, elastic and covalent organic polymers having pores of various sizes simply and quickly without a heating step or a purification step. Also, the covalent organic polymers can be used in various ways as an adsorbent for natural gas because the storage capacity of natural gas is very high due to a flexible porous network structure of the covalent organic polymers, thereby being suitable for transport and storage of natural gas.COPYRIGHT KIPO 2021
Methods for separating magnetic nanoparticles are provided. In certain embodiments, a method is provided for separating magnetic nanoparticles comprising: providing a sample comprising a plurality of magnetic nanoparticles; passing the sample through a first magnetic field; at least partially isolating nanoparticles of the first nanoparticle size desired; altering the strength of the first magnetic field to produce a second magnetic field; and at least partially isolating nanoparticles of the second nanoparticle size desired.
Engineered nanoparticles for water treatment application
J. Byun, C. T. Yavuz
2016
Chapter 2 in Engineered Nanoparticles and the Environment: Biophysicochemical Processes and Toxicity, Edited by B. Xing, C. D. Vecitis, N. Senesi.
WILEY-IUPAC Series in Biophysico-Chemical Processes in Environmental Systems
Published by John Wiley & Sons, Inc.
In this chapter, water treatment processes using nanoparticles and studies related to the removal of waterborne contaminants, such as anionic, cationic, and organic pollutants, will be reviewed.
Nano Rust
Cafer T. Yavuz
2008
My first book was recently published via VDM Verlag. Thanks to Gabriel Caruntu for hooking me up with them. If you're interested in buying please click here, it's only $116(!).
Here's the blurb from the back:
This work describes the first size dependent magneticseparation in nanoscale by using rust like iron oxide. Magnetite (Fe3O4) nanocrystals of high quality and uniform size (4 nm to 33 nm) were synthesized. Batch synthesis was shown to go up to 20 grams which is more than 10 times of a standard nanocrystal synthesis, without loosing the quality and monodispersity. Reactor design for mass (1 gram per hour) production of magnetite nanocrystals isreported for the first time. A green synthesis thatutilizes rust and edible oils was developed.
The cost of a kg of magnetite nanocrystals was brought down from $2600 to $22. Size dependency of magnetism was shown in nanoscale for the first time. Reversible aggregation theory was developed to explain the low field magnetic separation and solution behavior of magnetite nanocrystals. Arsenic was removed from drinking water with magnetite nanocrystals 200 times better than commercial adsorbents. Silica coating was successfully applied and magnetite - silica nanoshells were functionalized with amino groups. For the first time, silver was coated on the magnetite -silica nanoshells to produce triple multishells.
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