Pickering Emulsion Interfacial Engineering Synergized with Bimetallic Electronic Modulation for Selective Hydrogenation.

Breaking the trade-off between activity and selectivity in heterogeneous hydrogenation of multifunctional substrates remains a formidable challenge. In this work, we present a strategy for regulating the selective hydrogenation of p-chloronitrobenzene (p-CNB) by synergistically modulating the interfacial microenvironment and the electronic structure of the active sites. A functionalized quaternary ammonium polyether surfactant was designed to self-assemble on SiO2-OH nanoparticle surfaces via electrostatic interactions and hydrophobic effects, forming a Pickering emulsion interface with metal-chelating capability that served as a microreactor for in situ anchoring of PdCu bimetallic catalysts. Systematic experiments and density functional theory (DFT) calculations revealed a unique synergistic catalytic mechanism in which water molecules at the Pickering emulsion interface stabilized reaction intermediates through hydrogen bonding, substantially reducing the activation barrier for N-O bond cleavage and facilitating product desorption. Concurrently, Cu2+ incorporation deactivated Pd sites toward C-Cl bond activation through electronic and geometric effects, thereby suppressing dehalogenation side reactions. Benefiting from this synergy, the catalyst achieved ≥99.9% conversion with 95.4% selectivity toward p-chloroaniline under mild conditions while maintaining excellent recyclability. This work integrates Pickering emulsion interfacial engineering with bimetallic electronic modulation, providing new insights for rapidly constructing efficient interfacial catalytic systems to address the selective transformation challenges of complex substrates.