Microenvironment mediated laser synthesis of transition-metal-compound nanoparticles in air

Multicomponent nanoparticles with tunable phase and composition are of great interest due to their unique electronic structures and size-dependent properties. Yet, a rapid, universal, and air-compatible route to phase-pure metal compounds remains challenging. Here, we develop a reaction microenvironment engineering-assisted pulsed laser shock (RME-PLS) strategy that expands laser-based synthesis from metals and alloys to a broad family of transition metal compound (TMC) nanoparticles, including oxides, phosphides, sulfides, and selenides. By regulating the local chemical microenvironment, this approach enables phase-selective synthesis in ambient air with high purity and short reaction time. Ligand-controlled PLS induces metal-to-oxide phase evolution, while precursor introduction of P/S/Se sources further extends the strategy to a universal RME platform. As a demonstration, carbon-coated TMC nanoparticles are used as electrocatalysts for water splitting. Notably, the laser-derived Fe 2 P@C reconstructs into α-FeOOH as the true active phase, which delivers exceptional catalytic performance and maintains stable operation at industrial current densities for more than 1000 h. In situ characterization reveals the structural evolution of the catalyst during water oxidation. In addition, the RME-PLS strategy enables tunable particle size control, highlighting its broad adaptability. This work establishes a general, scalable, and air-compatible platform for the rapid and phase-selective synthesis of transition metal compound nanoparticles.