Surface-level mechanistic studies of adsorbate–adsorbate interactions in heterogeneous catalysis by metals

Despite being considered a mature field, recent developments in experimental and theoretical techniques have greatly increased the fundamental understanding of complex surface processes in catalysis. One area of particular interest is the effect of co-adsorbed species on reactivity in heterogeneous systems. Experiments have demonstrated that co-adsorbed species, both organic and inorganic, can improve surface activity and selectivity. We begin by classifying adsorbate–adsorbate interactions that have been shown to alter the reactivity of a metal surface. We then review numerous systems where such effects have been observed using experiment or theory. Systems such as the hydrogenation of olefins with other carbonaceous adsorbates present, the chiral templating of surfaces, and the co-adsorption of alkalis, halides, and other inorganic “poisons” to improve selectivity are discussed in detail. Finally, future directions of study and outstanding questions are addressed.