Open Access
Review
16 July 2025Heterogeneous Catalyzed Electrochemical Conversion of CO2 through C-N Bond Formation
The electrocatalytic transformation of carbon dioxide into valuable chemical compounds has gained increasing significance, particularly in the production of nitrogen-containing species via C-N bond formation. This review is organized around the “nitrogen source as the main thread, the product as the branch, and the mechanism as the underlying logic”, summarizing and discussing the latest research work on the formation of C-N bonds involving CO2 under electrochemical conditions. Firstly, these works are classified by the N-containing substrates (oxynitrides, dinitrogen gas, and ammonia) and productions (urea, amines, amides, carbamates, and amino acids). Then, various types of electrocatalysts are demonstrated in depth, including experimental and theoretical results. Finally, the conclusion is presented as well as the future perspectives.
Open Access
Article
23 July 2025Harnessing Nature’s Colours: Experimental and Computational Insights into Bixa orellana Pigments for Next-Generation Dye-Sensitized Solar Cells
The potential of Bixa orellana (annatto) pigments, specifically bixin and norbixin, as sensitizers for dye-sensitized solar cells (DSSCs) was investigated. The pigments were extracted using various solvents (acetone, methanol, ethanol, and hexane), and their optical and photo-electrical properties were investigated using UV-Vis spectroscopy and photoelectrical analysis. Results indicate that acetone extract (a-AP) exhibited the highest power conversion efficiency (PCE) of 0.786%, attributed to its broad absorption spectrum and optimal electronic properties. Quantum chemical calculations revealed that both bixin and norbixin exhibit favourable frontier orbital energies and energy gaps, making them well-suited for efficient electron injection and light absorption. These findings position Bixa orellana pigments as promising, eco-friendly alternatives to conventional synthetic sensitizers, offering a pathway toward more sustainable, locally adaptable, and efficient solar energy harvesting.
Open Access
Article
01 August 2025Eastern Lubber Grasshopper Extract-Inspired Silver Nanoparticles Selectively Inhibit Methicillin-Resistant Staphylococcus aureus
Silver nanoparticles (AgNPs) were synthesized using a protein/polypeptide-rich aqueous extract from the Eastern lubber grasshopper (Romalea microptera), as a natural reducing and capping agent. The resulting AgNPs exhibited relatively uniform sizes (10–60 nm) and were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-visible (UV-Vis) spectroscopy, Transmission electron microscopy (TEM), and Scanning Electron Microscopy (SEM). Disk diffusion tests against five bacterial strains (Methicillin-resistant Staphylococcus aureus (MRSA), Burkholderia cenocepacia, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli) demonstrated that the insect-extract-induced AgNPs selectively and significantly inhibited MRSA growth, with an average value of zone of inhibition of 9.16 ± 1.11 mm (n = 4). Statistical analysis confirmed the superior antibacterial activity of the Eastern lubber grasshopper-derived AgNPs against MRSA compared to citrate-capped AgNPs and free silver ions. These findings reveal the potential of insect-derived AgNPs as selective, green-synthesized antibacterial agents with enhanced efficacy and reduced side effects, particularly against antibiotic-resistant pathogens.
Open Access
Review
07 August 2025Progress in the Study of Transition Metal-Based Carbon Nanotube Composites for Electrochemical Hydrogen Evolution
Hydrogen is an efficient, clean, and economical energy source, primarily due to its remarkably high energy density. Electrolytic water is considered an attractive and feasible method for hydrogen production. The high cost and scarcity of traditional Pt-based catalysts limit their large-scale application. Transition metals (TMs)-based composites, particularly those integrated with carbon nanotubes (CNTs), have emerged as promising alternatives due to their high conductivity, surface area, and ability to enhance the catalytic properties of TMs. Currently, there is no systematic summary of TMs-based CNTs composites for electrochemical hydrogen evolution reaction (HER). In this review, the main synthesis methods, including the wet chemical method, chemical vapor deposition, and electrochemical techniques, were first summarized. Then, the latest advancements of TMs/CNTs composites, focusing on their structure, electronic properties and superior HER catalytic performance, were systematically discussed. The catalytic mechanisms are meticulously examined, with particular emphasis on the pivotal role of CNTs in enhancing charge transfer and stabilizing metal nanoparticles. Finally, this review addresses the current challenges and future development directions for HER catalysts.
Open Access
Article
18 August 2025Ethanothermal Synthesis of Dual Emissive Supramolecular Carbon Dots from Naphthalenediol and Quinones with Aggregate Tuned Fluorescence
Carbon dots (CDs) have attracted considerable interest due to their unique photoluminescence and broad potential in sensing, bioimaging, and optoelectronics. However, precise control of their emission properties through molecular design and understanding of supramolecular aggregation remain challenging. Here, nitrogen-doped carbon dots (H-CDs) with green fluorescence are synthesized via an ethanol-mediated solvothermal method using 1,3-dihydroxynaphthalene as a rigid π-conjugated carbon source and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as both oxidant and nitrogen donor. The synthesis involves complex molecular transformations yielding amorphous supramolecular carbon dots stabilized mainly by noncovalent interactions. Characterization confirmed abundant oxygen- and nitrogen-containing functional groups and an amorphous structure devoid of crystalline residues. Hierarchical H-type aggregation driven by π-π stacking and hydrogen bonding governs the photophysical behavior of the H-CDs, inducing a concentration-dependent evolution from blue-emitting monomers to green-emitting supra-CDs, accompanied by particle growth, red-shifts in the emission spectrum, and a pronounced elongation of the fluorescence lifetime. Temperature- and salt-dependent studies reveal that emission intensity increases with rising temperature and low ionic strength, due to distorted H′-aggregates with weak excitonic coupling and electrostatic screening of surface charges. These insights deepen the understanding of structure-property relationships in carbon dots and offer guidance for tailoring their photophysical properties for advanced optoelectronic applications.
