Lattice‐Strain Engineering of High‐Entropy‐Oxide Nanoparticles: Regulation by Flame Spray Pyrolysis with Ultrafast Quenching

The lattice-strain engineering of high-entropy-oxide nanoparticles (HEO-NPs) is considered an effective strategy for achieving outstanding performance in various applications. However, lattice-strain engineering independent of the composition variation still confronts significant challenges, with existing modulation techniques difficult to achieve mass production. Herein, a novel continuous-flow synthesis strategy by flame spray pyrolysis (FSP) is proposed, which air varying flow rates is introduced for fast quenching to alter the cooling rate and control the lattice strain of HEO-NPs. Experimental results demonstrate that as the flow rate of air increases from 0 L to 24 L min^-1, the cooling rate has increased by more than ten times, and the tensile strain of the HEO-NPs increases by 2.75%. Utilizing the oxygen evolution reaction (OER) activity as an indicator, it is observed that the overpotential to achieve a current density of 10 mA cm^-2 is reduced by 25 mV. Importantly, this approach enables the simple and efficient regulation of lattice strain in HEO-NPs (110 mg min^-1). Thus, this study provides a new approach for both the mass production and regulation of lattice strain in HEO-NPs.