The advancement of synthesizing high entropy alloy nanoparticles (HEA-NP) has opened up new research directions for electrocatalyst preparation. The HEA-NPs offer improved electrocatalytic performance due to the synergistic effect of five or more elements mixed in a solid solution. However, popular techniques (such as wet chemical synthesis) often face complications in synthesizing HEA nanoparticles. The complexity arises mainly from the thermodynamic requirements of excessively high temperature, faster cooling rate, and miscibility of elements in a wet chemical process. Herein, we report Intense Pulse Light (IPL) assisted high entropy alloy nanoparticle synthesis capable of overcoming the barriers of processing HEA-NPs. In this technique, a millisecond spanning intense flash light generated by a xenon lamp irradiates the dried mixed precursor solution deposited on a substrate. The substrate and the dried precursor solution heats up rapidly, achieving temperature high enough to reduce the precursors and homogeneously mix the elements at nanometer-scale on the favorable nucleation sites of the substrate. Leveraging the benefits of this technique, FeNiCo, FeNiCoCr, FeNiCoMn, FeNiCoCrMn nanoparticles are formed on a carbon-based substrate with pulses spanning only 21ms of time. The size of the nanoparticles widely varies from less than 10 nm to as big as 250 nm. The produced transition metal low-cost HEA-NPs are capable of achieving excellent catalytic performance compared to the state-of-the-art IrO catalyst for alkaline water splitting half-cell oxygen evolution reaction. The synthesized FeNiCoCr, FeNiCoCrMn, FeNiCo, and FeNiCoMn nanoparticles showed overpotentials of 250, 268, 279, and 302 mV at 10 mA/cm2, respectively in linear sweep voltammetry measurement compared to 317 mA for IrO, under the same conditions. The high entropy alloy nanoparticle catalyst produced can be a good candidate for the anion exchange membrane electrolysis cell (AEMEC).

Intense Pulsed Light (IPL) processing of high entropy alloy nanoparticle catalysts for oxygen evolution reaction

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