Three-dimensional layered double hydroxides on carbon nanofibers: The engineered mass transfer channels and active sites towards oxygen evolution reaction

Developing cost-effective, highly active and durable electrocatalysts for the oxygen evolution reaction are critical for electrolyzers and metal-air batteries. Although the cutting-edge transition metal-based layered hydroxides have been intensively investigated towards oxygen evolution reaction, the non-negligible issues of low electronic conductivity and idiopathic aggregation of hydroxide layers are not well addressed, which likely lead to significant ohmic resistance and mass transfer limitation, respectively. Herein, we report a three-dimensional composite catalyst of FeNi layered double hydroxide propped by Fe, N co-doped carbon nanofibers. The introduction of a spacer, Fe, N co-doped carbon nanofibers, not only improves the conductivity, but also exposes more active sites and provides rich porous structures for mass transfer. Reasonably, the composite catalyst demonstrates an excellent activity towards oxygen evolution reaction with only 0.263 V in overpotential at the current density of 10 mA cm⁻²; meanwhile, such a catalyst presents almost no fading after 1000 cycles between 1.0 and 1.6 V. In addition, a synergy between Fe, N co-doping in carbon nanofibers and FeNi layered double hydroxide is revealed to account for the enhanced activity and durability in this report.