Catalysts

19 pages, 3018 KB

Open AccessArticle

Polypyrrole-Integrated Lanthanum Ferrite Electrochemical Platform for Sensitive Detection of Tinidazole

by Shakoor Ahmed Solangi, Jameel Ahmed Baig, Imam Bakhsh Solangi, Hassan Imran Afridi, Faisal K. Algethami, Khalil Akhtar, Sajjad Hussain, Latif Ullah Khan, Şükrü Gökhan Elçi and Mohamed N. Goda

Catalysts 2026, 16(6), 490; https://doi.org/10.3390/catal16060490 (registering DOI) - 22 May 2026

Abstract

In the present research, lanthanum ferrite nanoparticles (LaFeO₃ NPs) and lanthanum ferrite polypyrrole (LaFeO₃/PPy) nanocomposites were synthesized and evaluated for electrochemical sensing of TNZ in biological and pharmaceutical samples. LaFeO₃ NPs were synthesized using the sol–gel auto-combustion method, whereas LaFeO₃/PPy nanocomposites were produced through an in situ chemical oxidative polymerization process. The obtained materials were subjected to comprehensive characterization by multiple analytical techniques, including XRD, which confirms an orthorhombic crystal structure; SEM micrographs of LaFeO₃ NPs and LaFeO₃/PPy nanocomposites exhibit a highly agglomerated structure with non-uniform particle distribution and a more homogeneous, smoother surface morphology, respectively, with an average size of <70 nm. The LaFeO₃/PPy nanocomposites exhibited an electron-transfer process governed by diffusion, as evidenced by cyclic voltammetry (CV) analysis. Using differential pulse voltammetry (DPV), the sensor achieved quantitative detection across a linear concertation range of 0.1–230 µM (R² = 0.997), with a detection limit (0.023 µM). The developed sensor demonstrated excellent stability, remarkable sensitivity, and high reproducibility, confirming reliability and suitability (RSD% < 4.0) for the quantitative determination of TNZ in both biological and pharmaceutical matrices. Full article

(This article belongs to the Section Electrocatalysis)

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15 pages, 5263 KB

Open AccessArticle

Fabrication of FeNi@PDA Nanozyme-Driven Dual-Mode Platform for Visual and On-Site Monitoring of Ampicillin

by Weipeng Teng, Guizhu Wu, Hongwu Wu, Zhaoying Liu, Haining Chen, Zhen Zhang and Ming Li

Catalysts 2026, 16(6), 489; https://doi.org/10.3390/catal16060489 (registering DOI) - 22 May 2026

Abstract

The widespread accumulation of ampicillin (AMP) poses significant ecological and health risks, demanding rapid and portable monitoring tools. Herein, a Fe-Ni bimetallic-doped polydopamine (FeNi@PDA) nanozyme with exceptional peroxidase-like activity was synthesized for the visual and on-site monitoring of AMP. Optimized through bimetallic electronic coupling, FeNi@PDA exhibited enhanced catalytic efficiency (K_M = 0.051 mmol/L for H₂O₂ and 0.049 mmol/L for 3,3′,5,5′-tetramethylbenzidine) and generated ¹O₂ and ·O₂⁻ via H₂O₂ activation. Leveraging the competitive consumption of reactive oxygen species (ROS) by electron-rich AMP, a colorimetry detection mode was developed where AMP concentration inversely correlated with oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB) formation. This strategy achieved a good linear relationship of between 0.05 to 100 μg/mL, with a limit of detection (LOD) of 10.38 ng/mL. Furthermore, a smartphone-integrated paper-based detection mode was fabricated by immobilizing FeNi@PDA on filter paper. The color gradient of test papers, analyzed via smartphone imaging, enabled on-site AMP quantification with a LOD of 340 ng/mL. This work not only developed a novel Fe-Ni bimetallic nanozyme with enhanced peroxidase-like activity and established a competitive ROS-consumption sensing mechanism but also pioneered a dual-mode detection platform for low-cost, user-friendly ampicillin monitoring in environmental samples. Full article

(This article belongs to the Special Issue Design, Engineering, and Application of Enzyme Cascade Systems)

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26 pages, 5494 KB

Open AccessArticle

Freezing Non-Equilibrium Structural Defects in Integrated Cu₄MgO₅/ZnO Nanocomposites for Extended Visible-Light-Driven Solar Fuel Production

by Abdelatif Aouadi, Nader Shehata, Okba Zemali, Hocine Sadam Nesrat, Salah Eddine Laouini, Hafidha Terea, Djamila Hamada Saoud and Tomasz Trzepieciński

Catalysts 2026, 16(6), 488; https://doi.org/10.3390/catal16060488 - 22 May 2026

Abstract

The rational configuration of electronic band structures through deep-seated structural disorder remains a formidable challenge in sustainable solar-to-fuel conversion. Herein, we report a transformative kinetic strategy to “freeze” an extraordinary density of non-equilibrium structural defects within an integrated Cu₄MgO₅/ZnO nanocomposite. Synthesized via a chitosan-assisted coordination-combustion route followed by rapid thermal quenching, the material preserves a record crystallographic dislocation density of 1.09 × 1015 m⁻² and significant lattice microstrain (1.04 × 10⁻³). This engineered structural disorder induces a profound reconfiguration of the electronic landscape, generating a continuous manifold of sub-bandgap “tail states” that narrow the optical bandgap to a remarkable 1.34 eV. Consequently, the defect-rich architecture facilitates unprecedented dual-channel photocatalytic performance under simulated solar irradiation in an aqueous solution containing 5 vol% triethanolamine (TEOA) as a sacrificial electron donor; the catalyst achieved a hydrogen evolution rate of 17,700.0 µmol g⁻¹ h⁻¹ and a methane production rate of 172.50 µmol g⁻¹ h⁻¹—representing a 36.3-fold and 43.1-fold enhancement over commercial ZnO, respectively. With an apparent quantum yield of 8.42% at 420 nm and robust photostability—maintaining 95.3% of its activity over five consecutive cycles (25 h total)—this noble-metal-free ternary system bypasses the limitations of traditional heterojunctions. Our findings establish a new benchmark for defect-engineered catalysts, providing a scalable blueprint for high-efficiency carbon neutrality and solar fuel production. Full article

(This article belongs to the Special Issue Nanostructured Materials for Solar and Visible Light Driven Photocatalysis, 2nd Edition)

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Catalysts, Volume 16, Issue 6 (June 2026) – 3 articles

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