Interfacial kinetic engineering of Pickering emulsions constructed by hydrophobic Bi2MoO6 nanosheets for enhanced photocatalytic selective hydrogenation.

Selective hydrogenation of nitroarenes to aromatic amines using solar energy is a green route, but as a typical two-phase reaction, it is limited by sluggish mass transfer across the oil-water interface and the difficulty in regulating the wettability of photocatalysts. Herein, we propose a surfactant in-situ modification strategy to construct ultrathin hydrophobic Bi2MoO6 nanosheets with Br doping and abundant oxygen vacancies (BMO-15) by enabling interstitially doped Br- interact with cetyltrimethylammonium cation (CTA+) via Coulomb force to achieve hydrophobic modification and promote the formation of surface oxygen vacancies driven by maintaining electroneutrality. The constructed Pickering emulsion interfacial catalytic system stabilized by BMO-15 photocatalyst achieves 92% nitrobenzene (NB) conversion and 99% aniline selectivity within 4 h under 420 nm light irradiation without noble metals, significantly exceeding non-emulsion (36%) and BMO-0 emulsion (40%) systems. The excellent performance arises from the emulsion interfacial catalytic system, which boosts interfacial mass transfer efficiency and facilitates the separation of photogenerated electron-hole pairs. In addition, the doped Br- and oxygen vacancies facilitate NB adsorption and activation, narrow the bandgap structure, and broaden the visible-light absorption. This work thus not only provides a versatile platform for designing high-performance photocatalysts with tunable hydrophobicity and defect sites, but also unveils oil-water interfacial engineering as a key driver for two-phase photocatalytic performance enhancement.