In the present work, chemically modified graphene oxide (GO) was incorporated as a crosslinking agent into thin-film composite (TFC) nanofiltration (NF) membranes for water desalination applications, which were prepared by the interfacial polymerization (IP) method, where the monomers were piperazine (PIP) and trimesoyl chloride (TMC). GO was functionalized with monomer-containing groups to promote covalent interactions with the polymeric film. The composite GO/polyamide (PA) was prepared by incorporating amine and acyl chloride groups into the structure of GO and then adding these chemical modified nanomaterial during IP. The effect of functionalized GO on membrane properties and performance was investigated. Chemical composition and surface morphology of the prepared GO and membranes were analyzed by thermogravimetric analysis (TGA), Raman spectroscopy, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The fabricated composite membranes exhibited a significant increase in permeance (from 1.12 to 1.93 L m⁻² h⁻¹ bar⁻¹) and salt rejection for Na₂SO₄ (from 95.9 to 98.9%) and NaCl (from 46.2 to 61.7%) at 2000 ppm, when compared to non-modified membranes. The amine- and acyl chloride-functionalized GO showed improved dispersibility in the respective phase.

The effect of the nature of the catalyst on the performance and mechanism of the hydrogen oxidation reaction (HOR) is discussed for the first time in this work. HOR is an anodic reaction that takes place in anionic exchange membrane fuel cells (AEMFCs) and hydrogen pumps (HPs). Among the investigated catalysts, Pt exhibited the best performance in the HOR. However, the cost and the availability limit the usage. Co is incorporated as a co-catalyst due to its oxophylic nature. Five different PtCo catalysts with different Pt loading values were synthesized in order to decrease Pt loading. The catalytic activities and the reaction mechanism were studied via electrochemical techniques, and it was found that both features are a function of Pt loading; low-Pt-loading catalysts (Pt loading < 2.7%) led to a high half-wave potential in the hydrogen oxidation reaction, which is related to higher activation energy and an intermediate Tafel slope value, related to a mixed HOR mechanism. However, catalysts with moderate Pt loading (Pt loading > 3.1%) exhibited lower E_1/2 than the other catalysts and exhibited a mechanism similar to that of commercial Pt catalysts. Our results demonstrate that Co plays an active role in the HOR, facilitating H_ads desorption, which is the rate-determining step (RDS) in the mechanism of the HOR.

We evaluate the effectiveness of chelating resins (CR) derived from Merrifield resin (MR) and 1,2-phenylenediamine (PDA), 2,2’-dipyridylamine (DPA), and 2-(aminomethyl)pyridine (AMP) as adsorbent dosimeters for Ag⁺, Cu²⁺, Fe³⁺, and Pb²⁺ cations from water under competitive and noncompetitive conditions. MR-PDA, MR-DPA, and MR-AMP were obtained in a 95–97% yield and characterized by IR, fluorescence, and SEM. The ability of CRs as adsorbents was determined by batch and flow procedures. MR-PDA showed a batch adsorption capacity order of Fe³⁺ (29.8 mg/g) > Ag⁺ (2.7 mg/g) > Pb²⁺ (2.6 mg/g) at pH 3.4. The flow adsorption showed affinity towards the Ag⁺ cation at pH 7 (18.4 mg/g) and a reusability of 10 cycles. In MR-DPA, the batch adsorption capacity order was Ag⁺ (9.1 mg/g) > Pb²⁺ (8.2 mg/g) > Cu²⁺ (3.5 mg/g) at pH 5. The flow adsorption showed affinity to the Cu²⁺ cation at pH 5 (2.2 mg/g) and a reuse of five cycles. In MR-AMP, the batch adsorption capacity was Ag⁺ (17.1 mg/g) at pH 3.4. The flow adsorption showed affinity to the Fe³⁺ cation at pH 2 (4.3 mg/g) and a reuse of three cycles. The three synthesized and reusable CRs have potential as adsorbents for Ag⁺, Cu²⁺, Fe³⁺, and Pb²⁺ cations and showed versatility in metal removal for water treatment.

In this work, the synthesis of bimetallic Ag and Cu particles on carbon vulcan (AgCu/C) is reported, synthesized by a simple galvanic displacement method using citrate tribasic hydrate as a co-reducing agent and a commercial material based on Cu/C as a template. The materials were characterized by several physicochemical techniques, including TGA, ICP-OES, XRD, SEM, and BET. The catalysts were evaluated as cathodic catalysts for the oxygen reduction reaction (ORR) and were used for the preparation of membrane electrode assemblies for evaluation in an Anion Exchange Membrane Fuel Cell (AEMFC). The results were compared with the commercial Ag/C and Cu/C catalysts; the bimetallic catalyst obtained a higher power density, which was attributed to a synergistic effect between Ag and Cu particles.

This work reports the synthesis of PdNi bimetallic particles and Pd on Carbon black (Vulcan XC-72) by reverse microemulsion and the chemical reduction of metallic complexes. The physicochemical characterization techniques used for the bimetallic and metallic materials were TGA, STEM, ICP-OES, and XRD. Also, the electrocatalysts were studied by electrochemical techniques such as anodic CO stripping and β-NiOOH reduction to elucidate the Pd and Ni surface sites participation in the reactions. The electrocatalysts were evaluated in the anodic reaction in anion-exchange membrane fuel cells (AEMFC) and the hydrogen oxidation reaction (HOR) in alkaline media. The results indicate that PdNi/C electrocatalysts exhibited higher electrocatalytic activity than Pd/C electrocatalysts in both the half-cell test and in the AEMFC, even with the same Pd loading, which is attributed to the bifunctional mechanism that provides OH^- groups in oxophilic sites associated to Ni, that can facilitate the desorption of Hads in the Pd sites for the bimetallic material.

In this work, the preparation of dense blended membranes, from blends of poly(vinylidene fluoride) (PVDF), poly(ether sulfone) (PES) and polyethyleneimine (PEI) or Fumion^®, with possible applications in alkaline fuel cell (AEMFC) is reported. The blended PEI/Fumion^® membranes were prepared under a controlled air atmosphere by a solvent evaporation method, and were characterized regarding water uptake, swelling ratio, thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), ion exchange capacity (IEC), OH⁻ conductivity and novel hydroxide ion exchange rate (HIER), which is related to the mass transport capacity of the OH⁻ ions through the membrane. The effect of the chemical composition on its morphological and anion exchange properties was evaluated. It was expected that the usage of a commercial ionomer Fumion^®, in the blended membranes would result in better features in the electrical/ionic conductivity behaviour. However, two of the membranes containing PEI exhibited a higher HIER and OH⁻ conductivity than Fumion^® membranes, and were excellent option for potential applications in AEMFC, considering their performance and the cost of Fumion^®-based membranes.