Biodiesel presents a sustainable alternative to fossil fuels, yet traditional homogeneous catalysts like sodium and potassium hydroxide face challenges with separation and reuse. Calcium oxide (CaO) is an effective heterogeneous catalyst for biodiesel production, but its chemical instability under reaction conditions restricts its long-term performance. This study introduces MOF-mediated synthesis (MOFMS) of heterogeneous catalysts, specifically CaO@ZnO and ZnO@CaO nanocomposites, from inexpensive and non-toxic metal salts and linkers in water. Comprehensive characterization techniques, including XRD, FT-IR, BET, FE-SEM, ICP, and CO2-TPD, were employed to analyze these catalysts. When applied to biodiesel production from soybean oil at ambient temperature and pressure, CaO@ZnO and ZnO@CaO achieved impressive biodiesel conversion rates of 99% and 92%, respectively, within 25 min. Both catalysts maintained their activity over six utilization cycles, with Ca²⁺ leaching remaining below 4% (2% for CaO@ZnO and 4% for ZnO@CaO) after the sixth run. These results provide valuable insights into catalyst preparation and leaching control, enhancing reusability in biodiesel production. Future research should aim to improve the long-term stability and reusability of these catalysts, investigate their performance with various feedstocks, and evaluate the feasibility for industrial applications. © The Author(s) 2025.
This chapter offers a novel perspective on the current challenges and opportunities in hydrogen production and its applications. It opens with an introduction that underscores the significance of shifting towards cleaner energy sources, highlighting hydrogen as a promising alternative fuel due to its ecological advantages. The discussion focuses on photocatalysis as a sustainable and efficient method for utilizing solar energy to generate hydrogen. It further explores photoelectrochemical techniques, which effectively convert solar energy into hydrogen through innovative approaches. In addition, the chapter addresses the concept of plasmonic excitation, which enhances light absorption and boosts the efficiency of photocatalytic processes. The section on Z-scheme photocatalysts illustrates their potential to improve energy conversion by emulating natural photosynthesis. © 2025 Elsevier Inc. All rights reserved.
