The selective oxidation of hydrocarbons on metal surfaces is a crucial process in heterogeneous catalysis, which is widely used in the chemical industry for the production of various chemicals and materials. The efficiency and selectivity of these reactions are highly dependent on the surface structure and composition of the metal catalysts. Here, we will discuss how changes in the surface structure and composition can affect the selective oxidation of hydrocarbons.1. Surface structure: The surface structure of a metal catalyst plays a significant role in determining the adsorption, activation, and reaction of hydrocarbon molecules. Different surface structures, such as terraces, steps, and kinks, can provide different active sites for the adsorption and activation of hydrocarbon molecules. For example, step sites are generally more reactive than terrace sites due to their lower coordination numbers and higher unsaturated bonds. Therefore, changes in the surface structure can lead to variations in the adsorption energies, reaction barriers, and transition states, which ultimately affect the selectivity and activity of the catalyst.2. Surface composition: The surface composition of a metal catalyst can be altered by adding or removing specific elements, creating alloys, or modifying the oxidation state of the metal. These changes can significantly influence the electronic properties, adsorption energies, and reaction pathways of the catalyst, leading to variations in the selective oxidation of hydrocarbons. For example, adding a second metal to form a bimetallic catalyst can modify the electronic structure of the surface, resulting in changes in the adsorption energies and activation barriers for hydrocarbon oxidation. Additionally, the presence of specific elements, such as alkali metals or transition metals, can promote or inhibit certain reaction pathways, leading to changes in the selectivity of the catalyst.3. Surface defects: Defects, such as vacancies, adatoms, and dislocations, can also significantly influence the selective oxidation of hydrocarbons on metal surfaces. These defects can act as additional active sites for the adsorption and activation of hydrocarbon molecules, leading to changes in the reaction pathways and selectivity. For example, vacancies can provide low-coordinated sites that can enhance the adsorption and activation of hydrocarbon molecules, while adatoms can modify the electronic structure of the surface and promote specific reaction pathways.4. Surface coverage: The surface coverage of adsorbed species, such as hydrocarbon molecules, oxygen, or reaction intermediates, can also affect the selective oxidation of hydrocarbons on metal surfaces. High surface coverage can lead to changes in the adsorption energies, reaction barriers, and transition states, which can influence the selectivity and activity of the catalyst. Additionally, high surface coverage can also promote or inhibit specific reaction pathways by altering the availability of active sites and the interactions between adsorbed species.In summary, the selective oxidation of hydrocarbons on metal surfaces is highly sensitive to changes in the surface structure and composition. By understanding and controlling these factors, researchers can design and develop more efficient and selective catalysts for various industrial applications.