Transition Metal Compounds on Functionalized Multiwall Carbon Nanotubes for the Efficient Oxygen Evolution Reaction

Numerous studies have attempted the oxygen evolution reaction (OER), a key half-reaction for water electrolysis, with low-cost catalysts exhibiting high activity and durability. This study reports a novel catalyst-design strategy for the heterogeneous growth of iron oxide (Fe₂O₃) nanoparticles on surface-functionalized multiwall carbon nanotubes (MWCNTs) through pulsed laser ablation (PLA). Strong physicochemical interactions at the functional Fe₂O₃ nanoparticles/conductive MWCNT support interface are confirmed by spectroscopic and computational investigations; the functional interface promotes charge transfer kinetics and reduces the energy barrier for the rate-determining step of OER. Furthermore, semi-circularly arranged Fe₂O₃ nanoparticles on the one-dimensional tubular MWCNT support, originating from heterogeneous nucleation and growth during the PLA process, facilitate mass and ion transfer during the OER. Thus, the optimized nanohybrid (0.5Fe@MWCNT) exhibits a low overpotential (310 mV) to generate a current density of 10 mA cm^-2 and possesses excellent durability, maintaining a stable current output during 10 h of continuous OER in a 1.0 M KOH electrolyte. Moreover, this synthetic strategy is economically advantageous, as it requires a total processing time of less than 1 h.