Pollen-like self-supported FeIr alloy for improved hydrogen evolution reaction in acid electrolyte

Ir is recognized as efficient catalyst for hydrogen evolution reaction (HER). The high price, however, has hindered its application in the production of hydrogen. In this work, we prepared the self-supported FeIr alloy nanoparticles, taking advantage of solid-state synthesis method. The as-prepared FeIr alloy possesses a novel morphology of pollen, which is consist of smaller FeIr nanoparticles. DFT calculations reveal that the change of the free Gibbs for Ir is negative after the adsorption of active H, while it is positive for the case of Fe. Thus, the alloying of Fe and Ir not only effectively reduces the cost, but also can achieve more adequate adsorption of active H species. Benefitting from this, the as-prepared FeIr alloy nanoparticle exhibits superior HER performance with an overpotential of 19 mV at a current density of 10 mV/cm2 and a Tafel slope of 32 mV/dec, when tested in 0.5 M H2SO4, better than pure Ir and Pt/C. This work paves the way to the exploration of efficient alloy electrocatalysts for HER.