Unidirectional Hydrogen Migration Through Interfacial Engineering for Promoted Brønsted Acid Catalysis.

Abstract

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/TiO₂/Pt catalyst with spatially separated structure, where WO_x and Pt particles are dispersed on the outer and inner surfaces of porous TiO₂ nanotubes, respectively. This nanodevice permits forward H migration (Pt→TiO₂→WO_x) while suppresses the reverse path (WO_x→TiO₂), as directly evidenced by in situ x-ray absorption fine structure characterization under hydrogenation and H₂ generation reactions. This rectification behavior originates from the diode characteristics of the TiO₂-WO_x heterojunction, which hinders both proton and electron transfer from WO_x to TiO₂. Consequently, WO_x/TiO₂/Pt accumulates highly concentrated Brønsted acid sites in H₂ atmosphere and thus exhibits superior catalytic performance compared to the closely contacted WO_x-Pt/TiO₂ catalyst. Up to 5.3 times higher liquid alkane yield has been achieved over WO_x/TiO₂/Pt relative to WO_x-Pt/TiO₂ 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.