Unravelling the fundamental insights underlying “confinement effects” in enhanced electrocatalysis

Designing confined catalysis by harnessing “confinement effects”, defined as the modulated microenvironments and physical properties that alter reaction kinetics and selectivity induced by placing active sites into confined regions, is becoming increasingly important as a complement to traditional catalyst design strategies. This comprehensive review aims to provide an in-depth understanding of how and why “confinement effects” impact the process of energy conversion electrochemical reactions. Firstly, fundamental principles underlying the catalytic performance enhanced by “confinement effects”, including electronic structure perturbation, charge transfer acceleration, active sites stabilization, solvent properties modulation, and mass transport regulation will be introduced. Subsequently, a systematic analysis of advanced strategies for constructing confined catalysts will be conducted. We scrutinize advances in the design and implementation of confined catalysts for electrochemical reactions from three different dimensionalities, namely activity optimization, durability enhancement, and selectivity modulation. Finally, future research opportunities that merit heightened consideration to foster the proliferation of confined catalysis are also proposed. This review offers profound insights into the further exploitation of “confinement effects” for pursuing catalysts with exceptional performance, which is of pivotal importance in stimulating more innovations regarding on the energy conversion reactions.