Dr. Valdés-Morales, Héctor

This study reports the synthesis of erbium (Er)-doped bismuth ferrite (BiFeO3/BFO) nanoparticles at varying molar concentrations (5, 10, and 15 %) using a sol-gel method. X-ray diffraction (XRD) analysis reveals a structural transformation from rhombohedral to orthorhombic upon Er3+ doping, confirming the successful incorporation of Er3+ ions into the BFO lattice. High-resolution transmission electron microscopy (HRTEM) images show that Er-doping leads to a reduction in particle size and a modification of the surface morphology. The bandgap of the Er-doped BFO samples decreases from 2.34 to 2.15 eV with increasing Er content, attributed to the formation of new Er 4f energy levels within the band structure. The magnetic properties of the samples also improve with increasing Er concentration. Photoluminescence (PL) spectra show reduced PL intensity for the 10 % Er-doped BFO sample, indicating a decrease in recombination rates, while electrochemical impedance spectroscopy (EIS) reveals a reduction in charge transfer resistance. Among the samples, the 10 % Er-doped BFO photocatalyst exhibits the highest photocatalytic efficiency. This enhanced activity is attributed to two key factors: efficient separation and migration of photogenerated charge carriers, and a reduced recombination rate of electron-hole pairs, both driven by the rare-earth doping in BFO. Radical trapping experiments further identify hydroxyl (OH•) radicals as the primary species responsible for photocatalytic degradation. This study provides valuable insights into the tunability of BFO's bandgap energy and photocatalytic properties through Er doping.

For renewable energy, it is crucial to create effective photocatalysts with enhanced photo charge separation and transfer to produce photocatalytic hydrogen (H2) efficiently utilizing light energy. Due to their distinct qualities and features, carbonaceous materials have so far been shown to be high-performance co-catalysts to substitute some conventionally costly metal materials in photocatalytic water splitting. Here, a novel ternary nanocomposite, simple hydrothermal process ball milling assisted and wet impregnation approach, a promising ternary nanocomposite is created as an efficient solar light driven photocatalyst. Utilizing a variety of analytical techniques, 3 % Cu3P/ZnS/g-C3N4 nanocomposites as catalysts were characterized in order to check the hydrogen production and investigate their structural properties. The hydrogen production capability of the catalyst is studied by irradiating Na2SO3 + Na2S solutes using a halogen bulb (250 W). The results demonstrated that in terms of photocatalytic activity towards H2 production, 3 % Cu3P/ZnS/g-C3N4 catalyst performed better than 3 % Cu3P/ZnS, Cu3P, ZnS, and g-C3N4. A composite containing 7.5 wt% g-C3N4 demonstrated exceptional durability during photocatalytic hydrogen production, resulting in a 23,086 mol h− 1 g− 1 rate. Higher stability in electron-hole pairs created a higher absorption level of solar light could be responsible for this remarkable performance.

Antibiotic overuse and indiscriminate disposal ultimately lead to overexploitation of the ecosystems expanding requirements, producing significant environmental and biological consequences. Advanced oxidation processes (AOPs) have kindled the interest of many researchers in targeting the destruction of antimicrobial and waterborne pollutants. As a result, an improvement of low-cost, high-efficiency photocatalysts for the successful decomposition of antibiotics is critical for the cleaning of harmful contaminants in rivers and lakes. In the current work, a simple hydrothermal approach was used to create the bismuth vanadate nanoballs (BiVO4) anchored to the exterior of the ultrathin g-C3N4.It was named g-C3N4/BiVO4(X) (X = 5, 10, 15, and 20%) nanocomposites, and the photocatalytic removal of ciprofloxacin (CPX) and amoxicillin (AMX) was investigated using synthesized composites. According to the advanced characterization techniques, the synthesized composites exhibit superior purity and crystalline nature. The electron transfer occurring within the g-C3N4, in conjunction with the extension of BiVO4 nanoballs, enhances the generation of photoexcited electron−hole (e−/h+) pairs. This phenomenon contributes significantly to the improved photocatalytic activity observed in the g-C3N4/BiVO4 system. Furthermore, the photocatalytic efficiency exhibited by g-C3N4/BiVO4(10%) nanocomposites in antibiotic removal surpasses that of both bare materials and other composite counterparts. The elimination of antibiotics was aided by reactive oxygen species (ROS)such as O2•−, h+, and OH. Finally, g-C3N4/BiVO4(10%), the intermediate byproduct of CPX and AMX decomposition, was discovered, and a probable CPX and AMX removal route was postulated. The g-C3N4/BiVO4(10%) composite exhibits long-term stability after five cycles. This study applies a green and ecologically responsive technique to the development of high-performance photocatalysts for wastewater remediation.

This study sheds light on how the properties of titanium dioxide (TiO2) are influenced when it is modified with iron (Fe), leading to the formation of Fe-doped-TiO2, Fe2O3-TiO2 composite, and single-phase FeTiO3 systems. The structural formation of the materials, oxidation state, and chemical environments of the elements are analyzed using XRD and XPS techniques. Band structures with UV–visible light driven properties and suitable redox potentials with improved recombination resistance along with an active inter- and intra-charge transfers were observed for Fe2O3-TiO2 and FeTiO3 systems. The photocatalytic efficiency was found to be superior for FeTiO3 system, degrading ~97 and 100 % of phenol, malachite green and rhodamine B dyes in 150 min, respectively along with enhanced recyclability. Interestingly, a competitive S- and Z-scheme was predicted for Fe2O3-TiO2 composite, explaining its photocatalytic mechanism. The scavenger and total organic carbon analyses revealed the radicals driving the photocatalytic reactions and the nature of degradation products, respectively.

Background: The main goal of this work is to demonstrate the improvement of visible light absorption for water pollution applications while simultaneously ensuring efficient disintegration of the industrial crystal violet dye (CV) through photocatalytic degradation. This strategy aims to minimize the impact on the local ecosystem. Methods: This study utilized a simple solvent-free and novel solid-state mixing technique to synthesize α-Bi2O3 with surfactant-containing urea (U) and citric acid (CA) at 600 ◦C. The physicochemical properties were utilized to investigate morphological, structural, textural properties, optical, and photostability, the long lifespan of photogenerated charge carriers of hole-electron pairs, and the visible light energy that caused them to disintegrate. Findings: Significantly, the surfactant based on urea was successful in maturing a nanoflower-like α-Bi2O3 (U) with extremely high stability and a versatile application of photocatalysis crystal violet degradation at 83.9% within 60 min. The α-Bi2O3 (U) shows good long-term stability with a 94.8(%) relative standard deviation after the fifth cycle, and the mechanistic analyses were evaluated by trapping experiments. Furthermore, this work provides a strategy to design low-cost and high-efficiency novel methods for sustainable photocatalysts and further investigates environmental applications.

Hydrogen energy possesses immense potential in developing a green renewable energy system. However, a significant problem still exists in improving the photocatalytic H2 production activity of metal-free graphitic carbon nitride (g-C3N4) based photocatalysts. Here is a novel Cu3P/CdS/g-C3N4 ternary nanocomposite for increasing photocatalytic H2 evolution activity. In this study, systematic characterizations have been carried out using techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectra, UV–Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), surface area analysis (BET), electrochemical impedance (EIS), and transient photocurrent response measurements. Surprisingly, the improved 3CP/Cd-6.25CN photocatalyst displays a high H2 evolution rate of 125721 μmol h− 1 g− 1. The value obtained exceeds pristine g-C3N4 and Cu3P/CdS by 339.8 and 7.6 times, respectively. This could be the maximum rate of hydrogen generation for a g–C3N4–based ternary nanocomposite ever seen when exposed to whole solar spectrum and visible light (λ > 420 nm). This research provides fresh perspectives on the rational manufacture of metal-free g-C3N4 based photocatalysts that will increase the conversion of solar energy. By reusing the used 3CP/Cd/g-C3N4 photocatalyst in five consecutive runs, the stability of the catalyst was investigated, and their individual activity in the H2 production activity was assessed. To comprehend the reaction mechanisms and emphasise the value of synergy between the three components, several comparison systems are built.

A nanocomposite composed of α-Fe2O3/g-C3N4 is synthesized using a modified ultrasonication approach, which engineered a robust interfacial contact in the system. Phase formation and morphological features are confirmed via XRD and electron-microscopy techniques. XPS revealed the native oxidation states of the elements and chemisorption-mediated interactions in the system. This developed composite produced hydrogen at a rate of 1494 μmolg− 1 h− 1, which is around 6.6 times higher than the g-C3N4 system. The observed enhancement is attributed to the Z-scheme configuration, leading to the suitable band edge alignments, charge separation and extended lifetime of the carriers in the composite.

Micrometer-sized polycrystalline anatase particles are widely used in materials and life sciences, serving as essential components in photocatalytic materials. The ability to tailor their composition, shape, morphology, and functionality holds significant importance. In this study, we identified and examined the non-destructive route of Copper(II) implantation at the surface of polycrystalline TiO2. The [Cu(en)(Im)2]2+ complex ion demonstrated a remarkable affinity to concentrate and bind with the semiconductor’s surface, such as anatase, forming a surface-bound adduct: ≡TiO2 + [Cu(en)(Im)2]2+ → ≡TiO2//[Cu(en)(Im)2]2+. The misalignment of Fermi levels in TiO2//[Cu(en)(Im)2]2+ triggered electron transfer, leading to the reduction of the metal center, releasing Copper(I) in the process. Although less efficient, the released Copper(I) encountered a highly favorable environment, resulting in the formation of the surface complex TiO2:CuIIsc. The implanted Cu(I) was converted back into Cu(II) due to re-oxidation by dissolved oxygen. The penetration of the metal ion into the surface level of the polycrystalline TiO2 lattice was influenced by surface residual forces, making surface grafting of the Cu(II) ion inevitable due to surface chemistry. FTIR, UV–vis, Raman, XRD, EPR, and surface morphological (SEM, EDAX, and HRTEM) analyses identified the typical surface grafting of the Cu(II) cluster complex on the anatase surface matrix. Moreover, the XRD results also showed the formation of an impure phase. The TiO2 polycrystalline materials, modified by the incorporation of copper complexes, demonstrated an enhanced visible-light photocatalytic capability in the degradation of Rhodamine B dye in aqueous solutions. This modification significantly improved the efficiency of the photocatalytic process, expanding the applicability of TiO2 to visible light wavelengths. These studies open up the possibility of using copper complexes grafted on metal oxide surfaces for visible-light active photocatalytic applications. Moreover, this investigation not only showcases the improved visible-light photocatalytic behavior of copper-modified TiO2 polycrystalline materials, but also underscores the broader implications of this improvement in the advancement of sustainable and efficient water treatment technologies.

In this study, perovskite-structured lanthanum cobalt oxide(LaCoO3/LCO) systems with particle and flake morphologies were developed using sol−gel and hydrothermal methods, respectively, in order to investigate their morphological structure-dependent properties for potential supercapacitor applications. The structural analysis confirms that both methods yield LaCoO3with improved crystalline properties. The energy storage performance of the developed materials is studied in a three-electrode configuration using a 1 MKOH electrolyte. The results indicated superior electrochemical performance for the LCO nanoflakes, exhibiting specific capacitances of ∼215 F g−1 at a scan rate of 5 mV s−1 and ∼136 F g−1 at a current density of 1 A g−1. In comparison, the LCO nanoparticles showed ∼119 F g−1 at a scan rate of 5 mV s−1 and ∼99F g−1 at a current density of 1 A g−1. This difference can be largely attributed to their respective morphologies, porous structures, and surface defects. Further, the nanoflakes demonstrated an exceptional capacitance retention of ∼97% even after 5000 charge−discharge cycles. The findings of this study suggest that the properties of perovskite LaCoO3 can be tuned by adjusting its morphology through various synthesis methods, making LaCoO3 a viable and robust system for energy storage applications.

Ethylene is a plant hormone regulator that stimulates chlorophyll loss and promotes softening and aging, resulting in a deterioration and reduction in the post-harvest life of fruit. Commercial activated carbons have been used as ethylene scavengers during the storage and transportation of a great variety of agricultural commodities. In this work, the effect of the incorporation of copper oxide over activated carbons obtained from baru waste was assessed. Samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption at −196 °C, field-emission scanning electron microscopy (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDS), and infrared (IR) spectroscopy. The results showed that the amount of ethylene removed using activated carbon obtained from baru waste and impregnated with copper oxide (1667 μg g−1) was significantly increased in comparison to the raw activated carbon (1111 μg g−1). In addition, carbon impregnated with copper oxide exhibited better adsorption performance at a low ethylene concentration. Activated carbons produced from baru waste are promising candidates to be used as adsorbents in the elimination of ethylene during the storage and transportation of agricultural commodities at a lower cost.