Search Results (24)

Advanced oxidation processes (AOPs) utilizing peroxymonosulfate (PMS) have emerged as a promising technology for organic pollutant degradation due to their distinct environmental advantages. In this study, copper–iron bimetallic oxide catalysts with varying ratios were synthesized via a co-precipitation method to activate PMS for degrading simulated tetracycline hydrochloride wastewater. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The effects of key parameters—including the PMS concentration, catalyst dosage, initial pH, and tetracycline hydrochloride concentration—on the degradation efficiency were systematically investigated. The results demonstrated that the CuFe(2)/PMS system exhibited the highest degradation efficiency. Under optimal conditions (20 mg/L tetracycline hydrochloride, 0.4 mM PMS, 0.5 g/L CuFe(2) catalyst, and pH 3), this system achieved a 94.12% degradation rate of tetracycline hydrochloride within 120 min. The electron paramagnetic resonance (EPR) tests and radical quenching experiments identified sulfate radicals (SO₄·⁻) as the predominant reactive species. Furthermore, the XPS analysis elucidated the persulfate activation mechanism, while the liquid chromatography–mass spectrometry (LC-MS) identified the potential degradation pathways and intermediate products of tetracycline hydrochloride. Full article

Bimetals—materials composed of two metal components with dissimilar standard reduction–oxidation (redox) potentials—offer unique electronic, optical, and catalytic properties, surpassing monometallic systems. These materials exhibit not only the combined attributes of their constituent metals but also new and novel properties arising from their synergy. Although many reviews have explored the synthesis, properties, and applications of bimetallic systems, none have focused exclusively on iron (Fe)- and aluminum (Al)-based bimetals. This systematic review addresses this gap by providing a comprehensive overview of conventional and emerging techniques for Fe-based and Al-based bimetal synthesis. Specifically, this work systematically reviewed recent studies from 2014 to 2023 using the Scopus, Web of Science (WoS), and Google Scholar databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and was registered under INPLASY with the registration number INPLASY202540026. Articles were excluded if they were inaccessible, non-English, review articles, conference papers, book chapters, or not directly related to the synthesis of Fe- or Al-based bimetals. Additionally, a bibliometric analysis was performed to evaluate the research trends on the synthesis of Fe-based and Al-based bimetals. Based on the 122 articles analyzed, Fe-based and Al-based bimetal synthesis methods were classified into three types: (i) physical, (ii) chemical, and (iii) biological techniques. Physical methods include mechanical alloying, radiolysis, sonochemical methods, the electrical explosion of metal wires, and magnetic field-assisted laser ablation in liquid (MF-LAL). In comparison, chemical protocols covered reduction, dealloying, supported particle methods, thermogravimetric methods, seed-mediated growth, galvanic replacement, and electrochemical synthesis. Meanwhile, biological techniques utilized plant extracts, chitosan, alginate, and cellulose-based materials as reducing agents and stabilizers during bimetal synthesis. Research works on the synthesis of Fe-based and Al-based bimetals initially declined but increased in 2018, followed by a stable trend, with 50% of the total studies conducted in the last five years. China led in the number of publications (62.3%), followed by Russia, Australia, and India, while Saudi Arabia had the highest number of citations per document (95). RSC Advances was the most active journal, publishing eight papers from 2014 to 2023, while Applied Catalysis B: Environmental had the highest number of citations per document at 203. Among the three synthesis methods, chemical techniques dominated, particularly supported particles, galvanic replacement, and chemical reduction, while biological and physical methods have started gaining interest. Iron–copper (Fe/Cu), iron–aluminum (Fe/Al), and iron–nickel (Fe/Ni) were the most commonly synthesized bimetals in the last 10 years. Finally, this work was funded by DOST-PCIEERD and DOST-ERDT. Full article

Photocatalytic H₂ production is one of the most promising approaches for sustainable energy. The literature presents a plethora of carefully designed systems aimed at harnessing solar energy and converting it into chemical energy. However, the main drawback of the reported photocatalysts is their stability. Thus, the development of a cost-effective and stable photocatalyst, suitable for real-world applications remains a challenge. An ideal photocatalyst for H₂ production must possess appropriate band-edge energy positions, an effective sacrificial agent, and a suitable cocatalyst. Among the various photocatalysts studied, TiO₂ stands out due to its stability, abundance, and non-toxicity. However, its efficiency in the visible spectrum is limited by its wide bandgap. Metal doping is an effective strategy to enhance electron–hole separation and improve light absorption efficiency, thereby boosting H₂ synthesis. Common metal cocatalysts used as TiO₂ dopants include platinum (Pt), gold (Au), copper (Cu), nickel (Ni), cobalt (Co), ruthenium (Ru), iron (Fe), and silver (Ag), as well as bimetallic combinations such as Ni-Fe, Ni-Cu, Nb-Ta, and Ni-Pt. In all cases, doped TiO₂ exhibits higher H₂ production performance compared to undoped TiO₂, as metals provide additional reaction sites and enhance charge separation. The use of bimetallic dopants further optimizes the hydrogen evolution reaction. Additionally, porphyrins, with their strong visible light absorption and efficient electron transfer properties, have demonstrated potential in TiO₂ photocatalysis. Their incorporation expands the photocatalyst’s light absorption range into the visible spectrum, enhancing H₂ production efficiency. This review paper explores the principles and advancements in metal- and porphyrin-doped TiO₂ photocatalysts, highlighting their potential for sustainable hydrogen production. Full article

During the cold metal transfer (CMT) arc additive manufacturing process of steel/copper bimetallic materials, interfacial penetration cracks have been observed due to the significant differences in thermal and physical properties between steel and copper. To mitigate the occurrence of these penetration cracks and enhance the interfacial elemental diffusion at the steel/copper junction, this study aims to fabricate high-performance steel/copper bimetallic materials with a uniform microstructure using CMT arc additive manufacturing techniques. A reciprocating additive sequence was adopted, with steel deposited first, followed by copper. Four different interlayer compositions, Cu-Ni, Fe-Ni, Cu-Cr, and Ni-Cr, were applied to the steel surface before the deposition of aluminum bronze. These interlayers served as a transition between the steel and copper materials. The manufacturing process then continued with the deposition of aluminum bronze to achieve the desired bimetallic structure. After the addition of interlayers, all four sets of samples exhibited excellent macroscopic formability, with clear and smooth interlayer contours and no visible cracks or collapse defects at the junction interfaces. The mechanical properties of the composite walls were enhanced following the addition of the interlayers, with an increase in tensile strength observed across the samples. The sample with the Fe-Ni interlayer showed the most significant improvement, with a 52% increase in impact energy absorption. Furthermore, the sample with the Fe-Ni interlayer demonstrated a higher average hardness level than the other groups, which was associated with the distribution and content of the iron-rich phase and the β′ phase. Full article

Much progress has been made in the determination of As (III), while numerous electrochemical sensors based on metal nanomaterials with significant sensitivity and precision have been developed. However, further research is still required to achieve rapid detection and avoid interference from other metal ions (especially copper ions). In this study, bimetallic AuPt nanoparticles are electrochemically modified with screen printing electrodes. What’s more, L-cysteine also self-assembles with AuNPs through Au-S bond to enhance the electrochemical performance. To overcome the interference of Cu (II) in the sensing process, the reduced iron powder was chosen to remove Cu (II) and other oxidizing organics in aqueous solutions. The lowest detectable amount is 0.139 ppb, a linear range of 1~50 ppb with superlative stability by differential pulse anodic stripping voltammetry. Fortunately, the reduced iron powder could eliminate the Cu (II) with no effect on the As (III) signal. Full article

Remediation of organic dyes in natural waters is a significant environmental need under active study. This review analyzes bimetallic catalytic degradation systems that are based on the Fenton chemistry concept and that generate reactive oxygen species (ROS) as the agent of dye breakdown. Recently developed advanced oxidation processes (AOPs) take advantage of bimetallic heterogeneous catalysts to facilitate rapid rates and full degradation. Catalysts based on two metals including iron, copper, molybdenum, cobalt and magnesium are discussed mechanistically as examples of effective radical ROS producers. The reactive oxygen species hydroxyl radical, superoxide radical, sulfate radical and singlet oxygen are discussed. System conditions for the best degradation are compared, with implementation techniques mentioned. The outlook for further studies of dye degradation is presented. Full article

Copper and iron-based bimetallic nickel catalysts supported on Mesostructured Silica Nanoparticles (MSNs) with compositions of 50% Ni–5% Cu/MSN and 50% Ni–5% Fe/MSN were prepared using an impregnation method, and they were compared with a monometallic 50% Ni–MSN catalyst for their activity and stability in methane decomposition reaction. The influence of promoters, such as Cu and Fe, at different reaction temperatures (700 °C, 800 °C and 900 °C) was investigated. The results revealed that the Cu and Fe-promoted catalysts significantly increased the hydrogen yield in methane decomposition compared with the unpromoted catalyst. This could be attributed to the formation of Ni–Cu and Ni–Fe bimetallic alloys in the catalysts, respectively, and this favored the stability of the catalysts. With increasing reaction temperature, the hydrogen yield also increased. However, the hydrogen yield and the lifetime of the nickel catalyst were enhanced upon the addition of iron compared to copper at all the reaction temperatures. The analysis conducted over the spent catalysts validated the formation of multi-walled carbon nanotubes with a bamboo-like internal channel over the catalysts along with a high crystallinity and graphitization degree of the carbon produced. Full article

In this study, multi-walled carbon nanotubes (MWCNTs) were prepared by chemical vapour deposition (CVD) using acetylene as a carbon source over an iron catalyst. As-prepared MWCNTs were used to support modern mono-copper, palladium, and bimetallic palladium-copper catalysts, and their feasibility for hydrogen production was tested during steam reforming of methanol (SRM) and methanol decomposition (DM). The structural characteristics of the MWCNTs were evaluated using the SEM and XRD methods. The physicochemical properties of the monometallic and bimetallic catalysts were analysed using the TPR and XRD methods. The promotion effect of palladium on methanol conversion rate and H₂ productivity in the case of the copper catalysts was demonstrated. The enhanced activity of the Cu/MWCNTs after palladium promotion was due to the formation of Pd-Cu alloy compound. Full article

A comprehensive study of the catalytic properties of the copper-iron binary system supported on mordenite, depending on the iron valence—CuFe2MOR and CuFe3MOR—was carried out, and redox ability has been considered as a decisive factor in determining catalytic efficiency. Acidity was studied by TPD-NH₃, DRIFT-OH, and DRT methods. The total acidity of both samples was high. The Brönsted acidity is similar for both bimetallic samples and is explained by the acidity of zeolite; Lewis acidity varies greatly and depends on the exchange cations. A screening DRIFT study of CO and NO has shown redox capacity and demonstrated a potential for using these materials as catalysts for ambient protection. CuFe2MOR demonstrated stable Cu and Fe species, while CuFe3MOR showed redox dynamic species. As expected, CuFe3MOR displayed higher catalytic performance in NO reduction via CO oxidation, because of the easily reduced intermediate NO-complex adsorbed on the metallic Cu and Fe sites, which were observed through in situ DRIFT study. Full article

Advanced oxidation processes (AOPs) have been postulated as viable, innovative, and efficient technologies for the removal of pollutants from water bodies. Among AOPs, photo-Fenton processes have been shown to be effective for the degradation of various types of organic compounds in industrial wastewater. Monometallic iron catalysts are limited in practical applications due to their low catalytic activity, poor stability, and recyclability. On the other hand, the development of catalysts based on copper oxides has become a current research topic due to their advantages such as strong light absorption, high mobility of charge carriers, low environmental toxicity, long-term stability, and low production cost. For these reasons, great efforts have been made to improve the practical applications of heterogeneous catalysts, and the bimetallic iron–copper materials have become a focus of research. In this context, this review focuses on the compilation of the most relevant studies on the recent progress in the application of bimetallic iron–copper materials in heterogeneous photo–Fenton-like reactions for the degradation of pollutants in wastewater. Special attention is paid to the removal efficiencies obtained and the reaction mechanisms involved in the photo–Fenton treatments with the different catalysts. Full article

In this study, chalcopyrite (CuFeS₂), a natural mineral with a bimetallic structure, was used as the activator to generate radicals for removing organic pollutants from aqueous solutions via the activation of peroxymonosulfate (PMS). Sulfisoxazole (SIX), a sulfonamide antibiotic, was selected as the model pollutant. The results showed that chalcopyrite was highly reactive toward the activation of PMS; under the conditions of 50 µM PMS and 1 g/L chalcopyrite, approximately 95.7% of the SIX was degraded after reaction for only 5 min. An increase in the loading of chalcopyrite (0.25–2 g/L) promoted the degradation of SIX, while elevated levels of PMS (0.05–0.5 mM) slightly retarded the degradation kinetics. Although the best performance was observed under acidic conditions (pHs 3 and 4), near complete degradation of SIX was also achieved at pH 5.5. Identification of reactive species revealed that both a hydroxyl radical and a sulfate radical were formed in chalcopyrite–PMS oxidation, and they were responsible for the degradation of SIX. Trace amounts of copper and iron were leached out from chalcopyrite during the activation, and both the heterogeneous and homogeneous activation of PMS contributed to the generation of oxidizing radicals. Common water constituents including Cl⁻, ${{\mathrm{HCO}}_3}^{-}$, and natural organic matter at their environmentally relevant levels showed a limited effect on the degradation of SIX, which suggests that chalcopyrite–PMS oxidation has high reactivity and stability in the degradation of organic pollutants and shows great practical application potential. Full article

The production of electricity in a greener and more sustainable way by employing renewable sources is a great challenge in modern times. Photovoltaic systems represent an important possibility because sunlight is the most abundant renewable source. In this review article, recent studies (from 2018 to the present) involving novel iron and copper complexes employed as dyes in Dye-Sensitized Solar Cells (DSSCs) are reported; mono- and bimetallic Fe complexes, Cu-based dyes, and devices presenting both metals are discussed, together with the performances of the DSSCs reported in the papers and the corresponding values of the main parameters employed to characterize such solar cells. The feasibility of DSSCs employing copper and iron dyes, alone or in combination with other earth-abundant metals, is demonstrated. The proper optimization of the sensitizers, together with that of the electrolyte and of the semiconducting layer, will likely lead to the development of highly performing and cheap photovoltaic devices for future applications on a much larger scale. Full article

Mesoporous silica of MCM-41 type with spherical morphology was modified with copper, iron, or manganese as well as pairs of these metals by template ion-exchange (TIE) method. The obtained samples were characterized with respect to their structure (XRD), morphology (SEM-EDS), textural parameters (low-temperature N₂ sorption), surface acidity (NH₃-TPD), transition metal loadings (ICP-OES), their deposited forms (UV-vis DRS) and reducibility (H₂-TPR). The catalytic performance of monometallic and bimetallic samples in the selective catalytic reduction of NO with ammonia (NH₃-SCR) was tested. The best catalytic results presented a bimetallic copper-manganese sample, which was significantly more active than the mechanical mixture of monometallic copper and manganese catalysts. The synergistic cooperation of manganese and copper species is possibly related to charge relocation between them, resulting in activation of the catalyst in oxidation of NO to NO₂, which is necessary for the fast NH₃-SCR reaction. Full article

In this study, zero-valent iron-copper (Fe-Cu) and iron-nickel (Fe-Ni) bimetals were prepared by disc milling for the dehalogenation of trichloroethylene vapors. For both Fe-Ni and Fe-Cu, three combinations in terms of percentage of secondary metal added were produced (1%, 5%, 20% by weight) and the formation of the bimetallic phase by milling was evaluated by X-ray diffraction (XRD) analysis. The disc milled bimetals were characterized by a homogenous distribution of Ni or Cu in the Fe phase and micrometric size visible from scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) analysis and by a relatively low specific surface area (0.2–0.7 m²/g) quantified by the Brunauer–Emmett–Teller (BET) method. The reactivity of the produced bimetals was evaluated by batch degradation tests of TCE in the gas phase with 1 day of reaction time. Fe-Ni bimetals have shown better performance in terms of TCE removal (57–75%) than Fe-Cu bimetals (41–55%). The similar specific surface area values found for the produced bimetals indicated that the enhancement in the dehalogenation achieved using bimetals is closely related to the induced catalysis. The obtained results suggest that ZVI-based bimetals produced by disc milling are effective in the dehalogenation of TCE vapors in partially saturated conditions. Full article

A series of mono- and bi-metallic copper and iron samples were prepared by impregnation method on micro-spherical silica and used for the synthesis of methanol via CO₂ hydrogenation. Compared with conventional carrier oxides, micro-spherical silica has obvious advantages in terms of absorption capacity and optimal distribution of active phases on its surface, also exhibiting excellent heat resistance properties and chemical stability. The prepared catalysts were characterized by various techniques including XRF, XRD, SEM, TEM, H₂-TPR and CO₂-TPD techniques, while catalytic measurements in CO₂ hydrogenation reaction to methanol were performed in a fixed bed reactor at a reaction pressure of 30 bar and temperature ranging from 200 to 260 °C. The obtained results revealed that the mutual interaction of copper–iron induces promotional effects on the formation of methanol, especially on systems where Fe enrichment on the silica support favours the presence of a larger concentration of oxygen vacancies, consequently responsible for higher CO₂ adsorption and selective methanol production. Surface reconstruction phenomena rather than coke or metal sintering were responsible for the slight loss of activity recorded on the catalyst samples during the initial phase of reaction; however, with no appreciable change on the product selectivity. Full article