Electron Tunneling: The Key to Unlocking Schottky Heterojunctions in Photo/Electrocatalysis

The nature of enhancing photo/electrocatalytic performance lies in the effective transfer of electrons and generation of active sites. Single-component catalysts, however, exist in irreconcilable contradictions between light harvesting ability and redox ability in photocatalysis, as well as extreme ability for absorption/desorption behaviors at active sites in electrocatalysis. To overcome these limitations, the elaborate design of the Schottky junction facilitates the formation of regions with uneven electron density and internal electric fields arising from the discrepancy of work function-induced electron flow, boosting the separation of photoinduced charges and modulating the properties of active sites. Nevertheless, electron transfer across the heterointerfaces typically requires additional energy to surmount interfacial energy barriers due to the misalignment of energy levels, which is detrimental for photoinduced electrons lacking an external driving force. The electron tunneling effect, a quantum phenomenon in which electrons traverse energy barriers greater than their kinetic energy based on electrons’ wave nature rather than overcoming energy barriers, offers a compelling solution. By enabling more electrons to participate in redox reactions, electron tunneling significantly boosts the catalytic efficiency, providing a viable pathway to overcome the limitations of conventional heterojunction systems. This Perspective elucidates the fundamental principles of the electron tunneling effect in Schottky junctions and applications in photo/electrocatalysis while outlining the crucial strategies to enhance the electron tunneling effect.