Unidirectional Hydrogen Migration Through Interfacial Engineering for Promoted Brønsted Acid Catalysis

Though playing a critical role, the controllable and directional migration of reactive species in chemical reactions is still hard to achieve. Here, we propose an interfacial engineering strategy for constructing a hydrogen spillover nanodiode that channels hydrogen unidirectionally. Such a nanodiode design is materialized in a composite WO x /TiO 2 /Pt catalyst with spatially separated structure, where WO x and Pt particles are dispersed on the outer and inner surfaces of porous TiO 2 nanotubes, respectively. This nanodevice permits forward H migration (Pt→TiO 2 →WO x ) while suppresses the reverse path (WO x →TiO 2 ), as directly evidenced by in situ x‐ray absorption fine structure characterization under hydrogenation and H 2 generation reactions. This rectification behavior originates from the diode characteristics of the TiO 2 –WO x heterojunction, which hinders both proton and electron transfer from WO x to TiO 2 . Consequently, WO x /TiO 2 /Pt accumulates highly concentrated Brønsted acid sites in H 2 atmosphere and thus exhibits superior catalytic performance compared to the closely contacted WO x –Pt/TiO 2 catalyst. Up to 5.3 times higher liquid alkane yield has been achieved over WO x /TiO 2 /Pt relative to WO x –Pt/TiO 2 in the polyethylene hydrocracking reaction. This nanodiode design strategy is general and can be extended to other catalysts/species, offering mechanistic insight and boosting catalytic performance in diverse reactions.