Magic of hydrogen spillover: Understanding and application

The hydrogen spillover effect (HSPE) plays an important role in heterogeneous catalysis and hydrogen storage as an interfacial phenomenon, which facilitates the improvement of hydrogen storage properties of porous nanomaterials and indirectly or directly affects the reaction performance of multiphase catalytic reactions. The setting-up of the word “hydrogen spillover” opened up a new area to gain insight into the dynamic behavior of migrating hydrogen atoms on a catalyst surface. However, a comprehensive understanding of the HSPE is still lacking. Today, the development of advanced characterization techniques provides increasingly valuable information to further our understanding of the HSPE. Based on these considerations, in this review, we hope to provide some answers to the question “What is hydrogen spillover and how do we recognize it?”. To do this, we will rely on advanced characterization techniques as well as experimental and theoretical studies. Then, we discuss in detail the influences of the HSPE on hydrogen storage performance and the important catalytic effects of the HSPE in catalysis. These effects will be reviewed by looking through the catalytic results obtained in many reactions in thermal catalysis, electrocatalysis, and photocatalysis. Furthermore, based on the application potential of hydrogen spillover, we present some preliminary research proposals and discuss the opportunities and challenges that remain to be faced in this research area.