Two-dimensional crystal lattice confining atoms for electrocatalysis

Electrocatalysis technology offers an avenue toward renewable energy conversion and chemical synthesis, in which the reaction efficiency strongly depends on the electronic and structural properties of catalysts. Two-dimensional (2D) crystal lattices confining single atoms integrate the advantages of anisotropy of 2D crystal lattices and the maximized atomic utilization of confined single atoms, sparking immense interests in various electrocatalytic applications. 2D crystal lattices and single atoms are interdependent and mutually beneficial to each other, i.e., 2D crystal lattices can confine single atoms in a metastable state via a strong interaction to trigger unique catalytic activity, while the confined atoms can also modulate the intrinsic activity of 2D structures. Here, three typical materials with 2D crystal lattices, including one-atomic-layer graphene, three-atomic-layer MoS2, and the emerging multi-atomic-layer metallene, are discussed as the matrix to confine single non-metal or metal atoms for electrocatalysis. We summarize the history and present status for the development of these catalysts and also provide insights in the remaining challenges and future possibilities in this research area to inspire more meaningful works.