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1. The Dopamine Assisted Synthesis of MoO3/Carbon Electrodes With Enhanced Capacitance in Aqueous Electrolyte

   https://doi.org/10.3389/fchem.2022.873462  

   Norouzi, Nazgol ; Omo-Lamai, Darrell ; Alimohammadi, Farbod ; Averianov, Timofey ; Kuang, Jason ; Yan, Shan ; Wang, Lei ; Stavitski, Eli ; Leshchev, Denis ; Takeuchi, Kenneth J. ; et al ( April 2022 , Frontiers in Chemistry)

   A capacitance increase phenomenon is observed for MoO 3 electrodes synthesized via a sol-gel process in the presence of dopamine hydrochloride (Dopa HCl) as compared to α-MoO 3 electrodes in 5M ZnCl 2 aqueous electrolyte. The synthesis approach is based on a hydrogen peroxide-initiated sol-gel reaction to which the Dopa HCl is added. The powder precursor (Dopa) x MoO y , is isolated from the metastable gel using freeze-drying. Hydrothermal treatment (HT) of the precursor results in the formation of MoO 3 accompanied by carbonization of the organic molecules; designated as HT-MoO 3 /C. HT of the precipitate formed in the absence of dopamine in the reaction produced α-MoO 3 , which was used as a reference material in this study (α-MoO 3 -ref). Scanning electron microscopy (SEM) images show a nanobelt morphology for both HT-MoO 3 /C and α-MoO 3 -ref powders, but with distinct differences in the shape of the nanobelts. The presence of carbonaceous content in the structure of HT-MoO 3 /C is confirmed by FTIR and Raman spectroscopy measurements. X-ray diffraction (XRD) and Rietveld refinement analysis demonstrate the presence of α-MoO 3 and h-MoO 3 phases in the structure of HT-MoO 3 /C. The increased specificmore »capacitance delivered by the HT-MoO 3 /C electrode as compared to the α-MoO 3 -ref electrode in 5M ZnCl 2 electrolyte in a −0.25–0.70 V vs. Ag/AgCl potential window triggered a more detailed study in an expanded potential window. In the 5M ZnCl 2 electrolyte at a scan rate of 2 mV s −1 , the HT-MoO 3 /C electrode shows a second cycle capacitance of 347.6 F g −1 . The higher electrochemical performance of the HT-MoO 3 /C electrode can be attributed to the presence of carbon in its structure, which can facilitate electron transport. Our study provides a new route for further development of metal oxides for energy storage applications.« less
2. Remarkably improved electrochemical hydrogen storage by multi-walled carbon nanotubes decorated with nanoporous bimetallic Fe–Ag/TiO ₂ nanoparticles

   https://doi.org/10.1039/C8DT03897J  

   Akbarzadeh, Raziyeh ; Ghaedi, Mehrorang ; Nasiri Kokhdan, Syamak ; Vashaee, Daryoosh ( January 2019 , Dalton Transactions)

   Nanoporous bimetallic Fe–Ag nanoparticles (NPs) were synthesized using a facile chemical reduction method and used to decorate the surface of multi-walled carbon nanotubes (MWCNTs) for hydrogen sorption and storage. The effect of TiO 2 nanoparticles on the hydrogen storage properties of Fe–Ag/CNTs was further studied in detail. For this purpose, several nanocomposites of nanoporous bimetallic Fe–Ag/TiO 2 nanoparticles with different amounts of bimetallic Fe–Ag NPs were prepared via a hydrothermal method. The hydrogen storage capacity of the as-prepared nanocomposites was studied using electrochemical methods. The Fe–Ag/TiO 2 /CNT nanocomposite with 0.04 M bimetallic Fe–Ag NPs showed the highest capacity for hydrogen storage, which was ∼5× higher than that of pristine MWCNTs. The maximum discharge capacity was 2931 mA h g −1 , corresponding to a 10.94 wt% hydrogen storage capacity. Furthermore, a 379% increase in discharge capacity was measured after 20 cycles. These results show that Fe–Ag/TiO 2 /CNT electrodes display superior cycling stability and high reversible capacity, which is attractive for battery applications.
3. Electrospun TiO ₂ /carbon composite nanofibers as effective (photo)electrodes for removal and transformation of recalcitrant water contaminants

   https://doi.org/10.1039/D3VA00017F  

   Butzlaff, Ashley Hesterberg ; Jensen, Madeline ; Yan, Chenxu ; Ghanim, Abdulsattar ; Werth, Charles ; Cwiertny, David ; Mubeen, Syed ( July 2023 , Environmental Science: Advances)

   Electrochemical (EC) and photoelectrochemical (PEC) water treatment systems are gaining popularity, necessitating new electrode materials that offer reliable performance across diverse application platforms. For applications specifically targeting dilute chemical pollutants ( i.e. , parts-per-million concentrations or less), beneficial electrode properties include high surface area to overcome kinetic overpotential losses, low electrode areal electrical resistance, and high water permeability with sufficient mechanical strength for use in electroactive membrane-based treatment systems. Here, we used electrospinning to fabricate (photo)electrodes from carbon nanofibers (CNFs) containing titanium dioxide (TiO 2 ) nanoparticles. Optimal CNF/TiO 2 composites were electrochemically and photochemically active with a surface area of ∼50 m 2 g −1 and electrode areal resistance of 2.66 Ω cm 2 , values comparable to commercial carbon-based electrode materials ( e.g. , Kynol Activated Carbon Cloth). Transformation experiments with carbamazepine (CBZ), a recalcitrant organic contaminant, suggest CNF/TiO 2 electrodes function dually as sorbents, first binding CBZ prior to oxidation at positive applied potentials. Complete CBZ transformation was observed in both EC (dark) and PEC (UV light; 280 mW cm −2 ) systems over 90 minutes, with PEC systems exhibiting 1.5-fold higher transformation rates ( k obs ∼ 0.18 min −1 ) at +1.00 V ( vs.more »Ag/AgCl). Composite electrodes also exhibited stability across repeated use, yielding consistent current densities over five experimental cycles (120 min each) of CBZ transformation (0.25 ± 0.03 mA cm −2 ). Because of their high surface area, electrical conductivity, photoactivity, and electrochemical stability, these electrospun CNF/TiO 2 composites represent promising (photo)electrode alternatives for diverse EC and PEC applications.« less
4. Performance of activated carbons synthesized from fruit dehydration biowastes for supercapacitor applications

   https://doi.org/10.1002/ep.13030  

   Ciftyurek, Engin ; Bragg, Dustin ; Oginni, Oluwatosin ; Levelle, Ross ; Singh, Kaushlendra ; Sivanandan, Litha ; Sabolsky, Edward M. ( October 2018 , Environmental Progress & Sustainable Energy)

   This research documents variability in electrode performance of activated carbons (ACs) produced from two different commercial fruit dehydration wastes through hydrothermal carbonization and chemical activation pathway. Commercial spent osmotic solutions (SOSs) from blueberry dehydration (BSOS) and glycerated cherry dehydration (CSOS) waste materials were subjected to hydrothermal carbonization at 250°C under nitrogen conditions for 30 min to extract hydrochars. BSOS‐ and CSOS‐derived hydrochar powders were further activated using phosphoric acid at 900°C to produce ACs. Results showed that the two commercial fruit dehydration wastes resulted in ACs with different pore characteristics, where the AC‐CSOS showed a higher level diversity in mesoporosity in addition higher surface area once compared to AC‐BSOS. The produced ACs were utilized in a symmetrical electrical double layer supercapacitor (EDLCs) to measure their performance as an electrode. The EDLCs fabricated from AC‐CSOS delivered a higher level of performance, where these materials showed up to 48 F/g specific capacity. Overall, the AC electrodes derived from the SOSs were comparable to many bio‐derived electrodes used for EDLCs, but subsequent enhancement to surface chemistry and surface area is required to outperform some of the best ACs and engineered carbon materials in this application. © 2018 American Institute of Chemical Engineers Environmore »Prog, 38:e13030, 2019

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5. Degradable sugar-based magnetic hybrid nanoparticles for recovery of crude oil from aqueous environments

   https://doi.org/10.1039/D0PY00029A  

   Dong, Mei ; Song, Yue ; Wang, Hai ; Su, Lu ; Shen, Yidan ; Tran, David K. ; Letteri, Rachel A. ; Flores, Jeniree A. ; Lin, Yen-Nan ; Li, Jialuo ; et al ( January 2020 , Polymer Chemistry)

   In this work, we designed and fabricated a nanoscopic sugar-based magnetic hybrid material that is capable of tackling environmental pollution posed by marine oil spills, while minimizing potential secondary problems that may occur from microplastic contamination. These readily-defined magnetic nanocomposites were constructed through co-assembly of magnetic iron oxide nanoparticles (MIONs) and a degradable amphiphilic polymer, poly(ethylene glycol)- b -dopamine-functionalized poly(ethyl propargyl glucose carbonate)- b -poly(ethyl glucose carbonate), PEG- b -PGC[(EPC-MPA)- co -(EPC-DOPA)]- b -PGC(EC), driven by supramolecular co-assembly in water with enhanced interactions provided via complexation between dopamine and MIONs. The composite nanoscopic assemblies possessed a pseudo -micellar structure, with MIONs trapped within the polymer framework. The triblock terpolymer was synthesized by sequential ring-opening polymerizations (ROPs) of two glucose-derived carbonate monomers, initiated by a PEG macroinitiator. Dopamine anchoring groups were subsequently installed by first introducing carboxylic acid groups using a thiol–yne click reaction, followed by amidation with dopamine. The resulting amphiphilic triblock terpolymers and MIONs were co-assembled to afford hybrid nanocomposites using solvent exchange processes from organic solvent to water. In combination with hydrophobic interactions, the linkage between dopamine and iron oxide stabilized the overall nanoscopic structure to allow for the establishment of a uniform globular morphology, whereas attempts atmore »co-assembly with the triblock terpolymer precursor, lacking dopamine side chains, failed to afford well-defined nanostructures. The magnetic hybrid nanoparticles demonstrated high oil sorption capacities, ca. 8 times their initial dry weight, attributed, in part, to large surface areas leading to effective contact between the nanomaterials and hydrocarbon pollutants. Moreover, the naturally-derived polymer framework undergoes hydrolytic degradation to break down into byproducts that include glucose, ethanol and dopamine if not recovered after deployment, alleviating concerns of potential microplastic generation and persistence.« less