Research Outputs

Now showing 1 - 4 of 4
No Thumbnail Available
Publication

Carbon Dots: A multifunctional nano-sized giant tool forthe detection probe and physical reformation of NiMoO 4 inSolid-State for enriched energy storage application

2024, Dr. Valdes-Morales, Hector, Annamalai, Arun, Annamalai, Kumaresan, Ayyanduarai, Nagarajan, Ravichandran, Ramya, Annamalai, Padmanaban, Elumalai, Sundaravadivel

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.

No Thumbnail Available
Publication

Simple devising of N-doped carbon dots (N-CDs) as a low-cost probe for selective environmental toxin detection and security applications

2023, Dr. Valdes-Morales, Hector, Annamalai, Kumaresan, Annamalai, Arun, Ravichandran, Ramya, Jeevarathinam, Anandhavalli, Annamalai, Padmanaban, Elumalai, Sundaravadivel

Nitrogen-doped carbon dots (N-CDs) possess outstanding photostability and interesting physicochemical and photochemical properties. Herein, we present cyan-emitting N-CDs that were fabricated through the treatment of salicylic acid with ethylene diamine using a simple microwave-assisted method. It was observed that the reaction produced N-CDs that strongly emitted cyan light with a quantum yield (QY) of 33%. The N-CDs were examined with the assistance of HR-TEM, XPS, XRD, FTIR, PL, and UV measurements. Due to the fluorescence enrichment effect caused by the N atoms in carbon dots, these N-CDs can be used as a fluorescent material for the detection of nitro-explosives and toxic metal cations. The addition of picric acid resulted in splendid quenching of the N-CDs, with a limit of detection (LOD) value of approximately 82.9 nM that was ascribed to the Fo ¨rster resonance energy transfer between the N-CDs and the nitro-aromatics. Furthermore, the powerful coordination between oxygen-rich moieties and N-CDs for the detection of Fe3+ and Hg2+ cations induced fluorescence quenching through photo-induced electron transfer and the inner-filter effect pathway, leading to the effective recognition of metal ions. The sensor probe exhibited a wide-ranging linear response with an LOD of approximately 30 nM for Fe3+ and 160 nM for Hg2+ ions. Thus, the as-prepared N-CDs can function as a fluorescence sensor, a secure portable information device, and a paper-based probe for detection in biological systems.

No Thumbnail Available
Publication

Sustainable synthesis, superior performance: Nanoflower-like α-Bi2O3 from solvent-free solid state for photocatalytic crystal violet degradation

2024, Dr. Valdes-Morales, Hector, Ravi, Aswini, Annamalai, Padmanaban, Sankar, Vigneshwaran, Achutharaman, K., SaravanaVadivu, Arunachalam, MuthaiahPillai, VelayuthamPillai, Alharbi, Sulaiman

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.

Thumbnail Image
Publication

Electrochemical sensing of tyrosine and removal of toxic dye using self-assembled three-dimensional CuBi2O4/rGO microsphere composite

2021, Dr. Valdes-Morales, Hector, Annamalai, Padmanaban, Thangavelu, Dhanasekaran, Ramadoss, Manigandan, Subramani, SriNandhini, Muthu, Senthil, Perumalsamy, Ramasamy, Ranganathan, Suresh

In this work, a novel low-cost electrochemical sensor involving copper bismuthate (CuBi2O4) microspheres embedded in reduced graphene oxide (rGO) is described for electrochemical determination of L-Tyrosine (L-Tyr) and photocatalytic degradation of methylene blue (MB) in Parkinson’s disease treatment and industrial waste treatment, respectively. The rGO improves the electrocatalytic behaviours of CuBi2O4 and enhances the sensing performance of L-Tyr. At the optimized conditions, the nanocomposites show good long-term stability, reproducibility, and fast response with nanomolar detection (6.9 nM) at wide linear ranges of 83–1234 Ă— 10− 9 M (R2 = 0.9964) towards L-Tyr. Further, the photocatalytic dye degradation within 30 min was studied in the presence of CuBi2O4/rGO catalysts. The synthesized CuBi2O4/rGO composite enhances the dye degradation rate and shows good sensitivity to detect the L-Tyrosine compared to CuBi2O4. The results suggest that the self-assembled three-dimensional CuBi2O4/rGO microsphere is an excellent material for the detection of biomolecules and the removal of organic dyes.