Nickel (Ni) plays a key role in many industrially important catalytic applications owing to its unique inherent features and high catalytic activity. In recent years, nickel single-atom catalysts (Ni-SACs) with well-defined structures have received enormous research attention. Taking into consideration the fact that the catalytic reaction happens on the catalyst's surface, the atom utilization efficiency of SACs can ideally reach 100 %, leading to high catalytic efficiency. Due to the high catalytic activity and selectivity, Ni-SACs have been used in numerous significant electrocatalytic, photocatalytic, and thermocatalytic applications. This review provides a critical analysis of the relevant recent progress in Ni-SACs for catalytic applications, and the remaining challenges are discussed for researchers interested in this emerging research area, leading the way to logically design the advanced Ni-SACs for different catalytic processes in the field of energy conversion and storage, and chemical transformations.
