Abstract
<jats:p> Continuous-flow nanosecond microparticle laser fragmentation in liquids (ns-MP-LFL) is investigated as a scalable route for producing LaB <jats:sub>6</jats:sub> nanoparticles from ball-milled ceramic feedstock. LaB <jats:sub>6</jats:sub> serves as a conductive refractory ceramic to evaluate photothermal ns-fragmentation of high-melting, low-work-function materials. Optical–thermal analysis shows that, despite shallow UV absorption at 343 nm, nanosecond thermal diffusion enables substantial pulsed heating of submicrometer particles and defines the relevant feedstock size window. A fragmentation threshold of 1.8 J cm⁻² is identified for particles >100 nm. In pure water, the mass yield of particles <75 nm saturates at 46% for fluences ≥3.6 J cm <jats:sup>-2</jats:sup> , indicating that dissipative energy-coupling losses, rather than nominal fluence, limit further yield improvement. Additive studies show that citrate and isopropyl alcohol reduce nanoparticle yield, while FeCl₃ does not enhance fragmentation, suggesting that bulk solution absorption cannot compensate for inefficient energy deposition. NaOH improves electrostatic stabilization and reduces particle size, although yield remains below that in pure water. Hofmeister-active halide salts provide additional size control: chaotropic Br⁻ and I⁻ suppress larger residual particles and narrow the distribution, with Br⁻ yielding minimum mass-weighted sizes of 45 nm. The nanoparticles show improved oxygen evolution reaction activity compared to the ball-milled reference, including a threefold current density increase to 0.45 mA cm <jats:sup>-2</jats:sup> and a reduced Tafel slope of 110 mV dec <jats:sup>-1</jats:sup> . However, Hofmeister-derived smaller particles do not enhance catalytic performance, suggesting halide-induced interfacial effects. Overall, ns-MP-LFL is established as a continuous process for LaB <jats:sub>6</jats:sub> nanoparticle production, identifying fluence, feedstock size, pH, and ion-specific chemistry as key variables. </jats:p>