Gradient hole engineering enables direct photocatalytic ammoxidation of toluene to benzonitrile

Abstract

Nitriles are indispensable in pharmaceuticals and advanced materials, yet their synthesis remains constrained by hazardous reagents or activated precursors. Direct photocatalytic ammoxidation of toluene to benzonitrile offers a sustainable alternative but is impeded by the intrinsic activity‐selectivity trade‐off in C–H activation and the temporal mismatch inherent to multi‐component C–N coupling. Here, we break this limitation by constructing a gradient‐hole dual‐oxidation‐site architecture via the semi‐encapsulation of Ru nanoparticles by BiO _x overlayers. Unlike conventional approaches that seek to maximize the density of highly active sites, this architecture electronically decouples the two critical oxidative pathways through reverse hole migration: hole‐enriched Ru centers selectively activate NH ₃ and stabilize N‐intermediates, while hole‐deficient BiO _x sites, along with oxygen vacancies, concurrently activate toluene and convert O ₂ to superoxide radicals for selective benzaldehyde formation. Moreover, this unique interface modulates the Bi–O p‐band and Ru d‐band centers synergistically, weakening benzaldehyde adsorption and reducing intermediate binding to lower the C–N coupling barrier. Consequently, we achieve complete toluene conversion with 94.74% benzonitrile selectivity and a production rate of 18.26 mmol·g _cat ⁻¹ under real solar irradiation, substantially outperforming prior systems. Beyond demonstrating a green route from toluene to benzonitrile, this electronically decoupled dual‐site architecture reconciles the activity‐selectivity trade‐off and orchestrates multi‐step transformations, offering a new blueprint for complex reaction networks.