Nanoscience has significantly impacted heterogeneous catalysis by enabling a molecular-level understanding of how nanoparticle properties influence catalytic performance. Catalysts, often nanoparticles dispersed on high-surface-area supports, are essential for producing many modern materials and reducing pollution. Advances in characterization and synthesis allow precise control over catalysts' size, shape, and composition, enhancing their activity and selectivity. Nanoparticles, typically 1-20 nm in size, play a critical role in catalytic reactions. For example, in automotive catalytic converters, nanoparticles like Pt, Rh, Ce, and lanthana are used to reduce emissions. The size and composition of nanoparticles affect their performance, as seen in the oxidation of CO and the oxidative dehydrogenation of alkanes. Gold nanoparticles on titania are active for CO oxidation, with optimal activity at 2-3 nm. Similarly, vanadia supported on oxides is effective for ODH, with activity increasing with particle size. Local composition and structure also influence catalytic performance. For instance, MoS₂ layers decorated with Co enhance desulfurization. TEM and EXAFS have provided insights into nanoparticle structures and compositions. Ru particles on titania show active sites for Fischer-Tropsch synthesis, with activity controlled by oxide coverage. Advances in characterization techniques like TEM, STM, and AFM allow detailed examination of nanoparticle structures under reaction conditions. Synchrotron radiation and EXAFS provide information on local composition and structure. These methods have shown that the oxidation state of catalysts affects product composition. Synthesis methods now enable precise control over nanoparticle size and shape, leading to single-site catalysts with uniform active sites. Single atoms on oxides are highly active for bond cleavage. Carbon nanotubes offer new support structures for metal particles, improving catalytic efficiency. Overall, nanoscience has advanced the understanding of catalyst performance, enabling the design of more efficient and selective catalysts. Advances in characterization and synthesis are crucial for achieving catalysis by design.Nanoscience has significantly impacted heterogeneous catalysis by enabling a molecular-level understanding of how nanoparticle properties influence catalytic performance. Catalysts, often nanoparticles dispersed on high-surface-area supports, are essential for producing many modern materials and reducing pollution. Advances in characterization and synthesis allow precise control over catalysts' size, shape, and composition, enhancing their activity and selectivity. Nanoparticles, typically 1-20 nm in size, play a critical role in catalytic reactions. For example, in automotive catalytic converters, nanoparticles like Pt, Rh, Ce, and lanthana are used to reduce emissions. The size and composition of nanoparticles affect their performance, as seen in the oxidation of CO and the oxidative dehydrogenation of alkanes. Gold nanoparticles on titania are active for CO oxidation, with optimal activity at 2-3 nm. Similarly, vanadia supported on oxides is effective for ODH, with activity increasing with particle size. Local composition and structure also influence catalytic performance. For instance, MoS₂ layers decorated with Co enhance desulfurization. TEM and EXAFS have provided insights into nanoparticle structures and compositions. Ru particles on titania show active sites for Fischer-Tropsch synthesis, with activity controlled by oxide coverage. Advances in characterization techniques like TEM, STM, and AFM allow detailed examination of nanoparticle structures under reaction conditions. Synchrotron radiation and EXAFS provide information on local composition and structure. These methods have shown that the oxidation state of catalysts affects product composition. Synthesis methods now enable precise control over nanoparticle size and shape, leading to single-site catalysts with uniform active sites. Single atoms on oxides are highly active for bond cleavage. Carbon nanotubes offer new support structures for metal particles, improving catalytic efficiency. Overall, nanoscience has advanced the understanding of catalyst performance, enabling the design of more efficient and selective catalysts. Advances in characterization and synthesis are crucial for achieving catalysis by design.