Abstract
<jats:p>Biodiesel is a sustainable alternative to fossil diesel, but its large-scale production is limited by inefficient conventional catalysts and fuel quality issues. Nanoparticles have emerged as promising materials due to their high surface area, enhanced catalytic activity, tunable surface chemistry, and excellent physicochemical properties. This review highlights the role of nanoparticles as nanocatalysts in biodiesel production and as fuel additives for improving combustion performance. Nanocatalysts enhance transesterification by increasing active sites, reducing activation energy, improving mass transfer, and accelerating reaction kinetics, resulting in higher biodiesel yields, shorter reaction times, lower catalyst consumption, easier recovery, and improved reusability. The review discusses major nanocatalysts, including calcium oxide, magnesium oxide, zinc oxide, titanium dioxide, aluminum oxide, magnetic nanoparticles, and mixed metal oxide nanocomposites, across various feedstocks. Nanoparticles used as fuel additives further improve combustion efficiency, brake thermal efficiency, ignition characteristics, and fuel stability while reducing emissions of carbon monoxide, hydrocarbons, and particulate matter. Despite these advantages, challenges such as nanoparticle agglomeration, production costs, long-term stability, environmental concerns, and limited standardization remain barriers to industrial application. Future research should focus on cost-effective synthesis, enhanced catalyst recyclability, reduced environmental impacts, and scalable production methods. Overall, nanoparticles offer significant potential to improve biodiesel production, fuel quality, and environmental sustainability, supporting the development of cleaner and more efficient renewable energy technologies.</jats:p>