Nanozyme-Based Catalysts for Renewable Fuel Production

As demand for clean fuels increases, there is growing interest in catalytic technologies that combine the functional properties of enzymes with the robustness and flexibility of nanomaterials. Nevertheless, the term “nanozyme” is often used to describe nanoscale heterogeneous catalysts and electrocatalysts regardless of proof of enzyme-like activity, which complicates understanding of renewable-energy technology development. This review discusses the difference between nanozymes and conventional nanocatalysts using common criteria of structure, kinetics, and mechanisms, and provides the methodology for substituting enzymes with nanozymes for renewable fuels. The relevant catalytic systems are classified based on the natural enzymes they imitate, including hydrogenase-like nanozymes for production of hydrogen, laccase-like nanozymes used as cathodes of biofuel cells, hydrolase- and cellulase-like nanozymes for biomass saccharification, formate dehydrogenase-like nanozymes for the conversion of carbon dioxide to formate, and carbonic anhydrase-like nanozymes for hydration and capture of CO2. In contrast, only nanoscale materials with features such as defect-mediated activity, surface adsorption, or electron-transfer enhancement are relevant to conventional catalysts unless other evidence simulating enzymatic processes has been presented. Enzymatic features, including enzyme-inspired coordination sites, enzyme-substrate cavities, relay organizations of protons, and spatial layouts of catalytic active sites, are main methods of improving the performance and efficiency of the catalyst. However, non-standard categorization of catalytic products, insufficient mechanistic justification of nanozymatic nature, no standardized ways of testing, high toxicity of materials, and limitations of scale-up affect the transfer of the product to the processing industries significantly. Therefore, a consolidated understanding of natural activation, catalyst design, catalytic mechanisms, and quantitative energy efficiency results in the creation of valid frameworks for the design of validated nanozymes in the area of environmentally friendly energy processing. The increasing global demand for sustainable energy has intensified the search for efficient, robust catalytic systems for renewable fuel production. At the same time, conventional catalysts, including natural enzymes and noble metal-based materials, continue to suffer from limitations such as poor stability, high cost, and limited scalability under industrial conditions. In this context, nanozyme-based catalysts have emerged as a promising alternative by integrating enzyme-like catalytic activity with the structural tunability, durability, and cost-effectiveness of nanomaterials. This review provides a comprehensive overview of recent advances in nanozyme-based catalysts for renewable fuel applications, beginning with the fundamental definition and classification of nanozymes based on their enzyme-mimicking activities. The review discusses mechanistic insights, emphasizing electron-transfer processes, active-site engineering, and catalytic pathways governing key energy reactions, including the hydrogen evolution reaction (HER), oxygen evolution and reduction reactions (OER/ORR), CO2 reduction, and biomass conversion into biofuels. The role of diverse material platforms, including metal-based, carbon-based, and hybrid nanozymes, is critically analyzed in terms of catalytic efficiency, selectivity, and stability. In addition, recent developments in computational modeling, particularly density functional theory (DFT), are highlighted for their contribution to predictive catalyst design and atomic-level mechanistic understanding. Despite these advantages, challenges related to toxicity, scalability, and real-world applicability remain significant barriers. Overall, nanozymes represent a next-generation catalytic platform with strong potential for sustainable fuel production, and future research should focus on in situ and in operando characterization, rational material design, and integration with renewable energy systems to support their transition to industrial deployment.