Ohmic/Schottky dual-junction in ReO2/TiO2−x/Re heterostructure enables suitable active sites for selective photoredox catalysis

Abstract

Semiconductor-based photocatalysis has garnered significant interdisciplinary attention owing to its considerable potential in addressing critical environment and energy sustainability challenges. However, it is a long-standing for semiconductor-based photocatalysts to synchronously realize high charge separation efficiency and construct suitable active sites, primarily due to uncontrollable charge transport and mismatched thermodynamic energy levels. Herein, we designed and constructed a novel ReO₂/TiO_2−x/Re Ohmic/Schottky dual-junction photocatalyst to achieve efficient coproduction of propyl propanoate and hydrogen (H₂). This unique heterostructure significantly enhances the charge separation efficiency by establishing two unimpeded charge transport pathways, while simultaneously improving charge utilization efficiency through the formation of specific dual active sites. Notably, the spatially separated active sites, endowed with appropriate redox abilities, facilitate the simultaneous activation of C_αH and OH in propan-1-ol. The resulting α-hydroxypropyl radical and propoxy radical intermediates play vital roles in enabling the selective production of propyl propanoate. Compared to pristine TiO₂, the ReO₂/TiO_2−x/Re heterostructure demonstrates a significantly enhanced H₂ production rate and superior selectivity for propyl propanoate. This work highlights the significance of meticulous structural design in creating Ohmic/Schottky dual-junction with optimized charge separation efficiency and tailored redox active sites, thereby enabling efficient photocatalytic H₂ evolution alongside value-added organic transformations.