Search Results (2)

The transition to clean and renewable energy sources is critically dependent on efficient hydrogen production technologies. This review surveys recent advances in photocatalytic water splitting, focusing on MNb₂O₆ nanomaterials, which have emerged as promising photocatalysts due to their tunable band structures, chemical robustness, and tailored morphologies. The objectives of this work are to (i) encompass the current synthesis strategies for MNb₂O₆ compounds; (ii) assess their structural, electronic, and optical properties in relation to photocatalytic performance; and (iii) elucidate the mechanisms underpinning enhanced hydrogen evolution. Main data collection methods include a literature review of experimental studies reporting bandgap measurements, structural analyses, and hydrogen production metrics for various MNb₂O₆ compositions—especially those incorporating transition metals such as Mn, Cu, Ni, and Co. Novelty stems from systematically detailing the relationships between synthesis routes (hydrothermal, solvothermal, electrospinning, etc.), crystallographic features, conductivity type, and bandgap tuning in these materials, as well as by benchmarking their performance against more conventional photocatalyst systems. Key findings indicate that MnNb₂O₆, CuNb₂O₆, and certain engineered heterostructures (e.g., with g-C₃N₄ or TiO₂) display significant visible-light-driven hydrogen evolution, achieving hydrogen production rates up to 146 mmol h⁻¹ g⁻¹ in composite systems. The review spotlights trends in heterojunction design, defect engineering, co-catalyst integration, and the extension of light absorption into the visible range, all contributing to improved charge separation and catalytic longevity. However, significant challenges remain in realizing the full potential of the broader MNb₂O₆ family, particularly regarding efficiency, scalability, and long-term stability. The insights synthesized here serve as a guide for future experimental investigations and materials design, advancing the deployment of MNb₂O₆-based photocatalysts for large-scale, sustainable hydrogen production. Full article

This study combines experimental and density functional theory (DFT) to evaluate the influence of alkaline cation characteristics on the electronic structure and photodegradation efficacy of organic dyes in MNbO₃ (M = Na, K) perovskites. The X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Near Edge Spectroscopy (XANES) spectra at the Nb edge of the Perovskites were employed to characterize its chemical and structural properties. The DFT calculations were carried out to simulate XANES spectra as well as the structural and electrical properties of KNbO₃ and NaNbO₃. Our results show that the simulated and experimental XANES spectra are similar, indicating that the computational simulations were able to capture the local structure of the niobate samples. In addition, a photocatalytic experiment was conducted to benchmark the methylene blue consumption efficiency between different niobates. The findings demonstrated that KNbO₃ is more efficient than NaNbO₃ for methylene blue UV photocatalytic degradation, which is associated with their electronic properties. This arises as a direct result of the variably deformed NbO₆ octahedra resulting from the different alkali used. Our findings facilitate the advancement of stable and abundantly available photocatalysts, which may be employed for energy-intensive processes such as the mineralization of organic water pollutants and hydrogen production by water splitting. Full article