Trimetallic FeNiMo Nanofibers as High-Efficiency Electrocatalyst for Robust Oxygen Evolution

Developing high-efficiency electrocatalysts without precious metals for the oxygen evolution reaction (OER) is still challenging in water electrolysis. Here, FeNiMo nanofibers (NFs) are successfully prepared via a facile electrospinning-calcination- in situ reduction strategy, which produces a FeNi 3 alloy and MoO 2 component. The FeNiMo NFs exhibit significant alkaline OER performance. Owing to the superior electron/mass transfer property from the nanofibrous morphology and the synergy between the FeNi 3 and MoO 2 components, the optimized Fe 0.125 Ni 0.375 Mo 0.5 NFs catalyst presents a small overpotential of 246 mV at 10 mA cm –2 with a Tafel slope of 49.21 mV dec –1 in 1 M KOH. These performances are significantly higher than the alkaline benchmark NiFe layered double hydroxide (LDH), commercial RuO 2 and many previously reported transition metal-based catalysts. Furthermore, a durability after 50 h of continuous chronoamperometric test with steady current density is demonstrated. In addition, an Fe 0.125 Ni 0.375 Mo 0.5 NFs||Pt/C full cell for water splitting delivers an ultralow voltage of 1.49 V at 10 mA cm –2, better than that for NiFe LDH||Pt/C (1.53 V) and RuO 2 ||Pt/C full cells (1.60 V). This study offers important new insights for the design of high-performance OER catalysts toward water electrolysis.