Dr. Valdés-Morales, Héctor

A facile photo-assisted strategy was developed for the in situ anchoring of Co²⁺ ions onto anatase TiO₂ nanoparticles through photoinduced electron transfer under UV irradiation, enabling the formation of stable Co–O–Ti interfacial bonds while preserving the anatase crystal structure. The Co²⁺-implanted TiO₂ nanoparticles were synthesized using the [Co(tn)₂(4-Mepy)Br]Br₂ complex as a precursor in an aqueous electrolyte under UV irradiation and subsequently characterized by XRD, TEM, EDS, FTIR, and XPS analyses, confirming the successful implantation of cobalt under mild reaction conditions. The resulting Co–TiO₂ nanoparticles exhibited pronounced room-temperature ferromagnetism, with saturation magnetizations (Mₛ) of 7.88 × 10⁻³ and 55.41 × 10⁻³ μ B per Co²⁺ and coercive fields (Hc) of 50.39 and 622.91 Oe for 0.37% and 0.68% Co doping, respectively, in contrast to the diamagnetic behaviour of pristine TiO₂. In addition to the enhanced magnetic properties, the Co–TiO₂ heterostructures exhibited bifunctional electrocatalytic activity toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, delivering overpotentials of 277.3 and 328.6 mV at 10 mA cm⁻² with corresponding Tafel slopes of 89.7 and 94.2 mV dec⁻¹ , respectively. The present facile room-temperature strategy simultaneously tailors the magnetic and electrocatalytic properties of TiO₂, highlighting the potential of Co–TiO₂ nanostructures for multifunctional magnetic and energy-conversion applications.

Effective management of polluted water from the textile industry remains a formidable challenge. This study introduces a novel approach to enhance photocatalytic capabilities for wastewater treatment. A Z-scheme heterojunction photocatalyst, comprising nitrogen-rich graphitic carbon nitride (g-C3N 5) and SnO2 , was synthesized via a simple thermal decomposition method. The pebble-like morphology of the SnO 2/10 wt% g-C3 N5 composite exhibited remarkable photodegradation efficiency under visible light. Specifically, it achieved 98.1% degradation of organic pollutants, surpassing bare g-C3 N5, SnO 2, and SnO 2/5 wt% g-C 3N5counterparts. The superior performance is attributed to enhanced charge separation facilitated by the Z-scheme mechanism, extending the photocatalyst’s activity into the visible spectrum. Stability tests revealed consistent high efficiency (degradation after five cycles), emphasizing the composite’s robustness. Mechanistic insights into the photocatalytic process highlight the piv-otal role of molecular oxygen (O 2) in pollutant degradation. This work advances understanding of photocatalytic mechanisms and underscores the composite’s potential for sustainable wastewater treatment in the textile industry.

In this work, a new approach for treating tannery wastewaters (TWWs) was applied, beginning with a coagulation-flocculation pretreatment. Under the optimal operating conditions obtained (5 g L−1 of ferric chloride at pH 7), this process was able to completely remove both turbidity and color present in the effluent, achieving a 73% of chemical organic oxygen (COD) removal. The sludge generated during the coagulation-flocculation (CF) process was valorized and characterized by XRD, FTIR, and SEM–EDX mapping and subsequently applied as a catalyst in an ultrasound-assisted photo-Fenton-like heterogeneous process (SPF). For this purpose, an experimental design based on Box-Behnken planning was employed to optimize the process operating parameters. Under the optimal conditions obtained (initial concentration of H2O2 of 2284 mg L−1, catalyst dosage of 2050 mg L−1 at pH = 3), complete CN removal and a 91% of COD reduction were achieved. Furthermore, phytotoxicity assessments based on germination percentage, germination rate index, and seedling vigor index showed a significant decrease in toxicity, with germination rates of 94% for both wheat and M. sativa seeds. With a total treatment cost of 4.8 $USD m−3 of treated TWW, the sequential treatment with CF followed by a heterogeneous SPF (CF-SPF) using a valorized sludge rich in Fe3+ as a catalyst, proved to be an efficient and viable alternative for the sustainable management of tannery wastewater.

A one-step synthesis approach was adopted to fabricate the rGO/SnO2 nanocomposite using reduced graphene oxide (rGO) along with tin chloride. The nanocomposite exhibited well-dispersed SnO2 particles anchored on rGO sheets owing to electrostatic interactions. The average particle size of SnO2 was around 8.0 ±0.2 nm, stabilized by π-electron interactions of the rGO. The synthesized rGO/SnO2 material served as a modifier for the glassy carbon electrode (GCE), forming an rGO/SnO2/GCE configuration. The modified electrode exhibited enhanced electrochemical activity and efficient electron transport in the Fe2+/Fe3+redox pair, enabling sensitive voltammetric detection of paracetamol under optimal conditions. The developed electrode offered excellent analytical performance, recording a sensitivity of 0.267 μA μM1 and detecting paracetamol concentrations as low as 0.04 μM across a broad linear range (0.1–130 μM). It also exhibited high selectivity, remaining unaffected by common interfering biomolecules. Finally, the fabricated rGO/SnO2/GCE sensor was applied to determine paracetamol levels in human urine and commercial tablet formulations, demonstrating excellent feasibility for real-sample and bioclinical analyses.

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.

The generation of hydrogen through the electrocatalytic water-splitting process is pivotal for the establishment of hydrogen economy. Yet, there remains a need to focus on abundant and non-toxic materials for this process to become more efficient and less polluting. In this study, we developed a low-cost, less toxic and bi-functional CeO2–V2O5–rGO (CVR) heterojunction nanocomposite electrocatalyst. Its performance is comparable to the benchmark Ni plate in a 1-M KOH solution, and it can be prepared via a straightforward solvothermal method at the lower temperatures. The newly synthesized electrocatalyst exhibits the remarkable performance in the overall water-splitting as a bi-functional electrocatalyst in the alkaline electrolyte medium. The onset potential of the CVR heterojunction nanocomposite for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is 1.75 and − 0.323 V versus reversible hydrogen electrode (RHE), respectively. A key significant finding of our research is that the reduced graphene oxide (rGO) considerably enhances the electronic conductivity of the bi-metallic oxides, leading to the efficient hydrogen production and moving us one step closer to an ideal platform for catalytic processes. Our work not only points toward the direction of efficient catalysts and improved the electrocatalytic performance of the two semiconductor nanomaterials with rGO but also offers an effective model for an in-depth mechanistic understanding of the electrochemical water-splitting.

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.

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.

Designing low-cost, effective and greener materials via a non-sophisticated strategy is most important for future research. Here, they made a new dual endeavor using carbon dots (CDs) as an environment protection probe for selective detection of environmental toxins, followed by the solid-state structural reformer to prepare NiMoO4 (NM) via mechanochemical-based solid grinding method. The prepared CDs, NM and NM-CDs combination is examined through various techniques. The prepared CDs selectively detect Cr6+, Ru3+, and Doxycycline independently. Also, in this work, a groundbreaking strategy is found to prepare morphology-tailored NM using CDs through a solid-state grinding method without adding any other toxic solvents or reagents. The CDs-induced NM-CDs (15) look like a 2D nano-sheet with enriched surface area compared to its bare NM. The fabricated electrode provides the highest capacitance value of 1947 F g−1, almost three times grander than the bare 1D rod-like electrode. Then, fabricated asymmetric supercapacitor NM-CDs (15)//AC system delivers a high energy density of 43.9 Wh Kg−1 at a power density of 684 W Kg−1. Overall, a single CDs serve multiple roles in the environment and energy applications with a greener structure tailoring agent and a better booster for re energy storage properties.

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.