Single-Step Direct Laser Writing of Multimetal Oxygen Evolution Catalysts from Liquid Precursors.

We investigate a laser direct-write method to synthesize and deposit metastable, mixed transition metal oxides and evaluate their performance as oxygen evolution reaction catalysts. This laser processing method enabled the rapid synthesis of diverse heterogeneous alloy and oxide catalysts directly from cost-effective solution precursors, including catalysts with a high density of nanocrystalline metal alloy inclusions within an amorphous oxide matrix. The nanoscale heterogeneous structures of the synthesized catalysts were consistent with reactive force-field Monte Carlo calculations. By evaluating the impact of varying transition metal oxide composition ratios, we created a stable Fe0.63Co0.19Ni0.18Ox/C catalyst with a Tafel slope of 38.23 mV dec-1 and overpotential of 247 mV, a performance similar to that of IrO2. Synthesized Fe0.63Co0.19Ni0.18Ox/C and Fe0.14Co0.46Ni0.40Ox/C catalysts were experimentally compared in terms of catalytic performance and structural characteristics to determine that higher iron content and a less crystalline structure in the secondary matrix decrease the charge transfer resistance and thus is beneficial for electrocatalytic activity. This conclusion is supported by density-functional theory calculations showing distorted active sites in ternary metal catalysts are key for lowering overpotentials for the oxygen evolution reaction.