Well-Aligned Arrangement CoFe Nanoparticles Assisted with Cellulose Nanofibrils for Efficient Oxygen Evolution Reaction

Abstract Searching for specific methods to make better use of the existing catalysts plays a significant role in achieving superior electrocatalytic performance. Herein, cellulose nanofibrils (CNF), featuring abundant carboxyls and hydroxyls, was employed to deposit cobalt (Co2+) and iron (Fe3+) ions. The Co2+ and Fe3+ ions were dispersed homogeneously and avoided idiopathic aggregation. The generated CoFe nanoparticles were in a well-aligned arrangement on the CNF nanocarbon. Benefiting from this unique structure, active sites were exposed and their catalytic ability was released fully. As a result, the overpotential of the as-synthesized CoFe nanoparticles catalyst (Fe-CoS/NC) was 257 mV to deliver a current density of 10 mA cm−2 with a Tafel slope of 46.7 mV dec−1 in 1.0 M KOH electrolyte, outperforming the commercial RuO2 remarkably. The Fe-CoS/NC catalyst exhibited excellent stability, which the overpotential to deliver a current density of 10 mA cm−2 was only increased by 2.82% after 50 h chronopotentiometry measurement. The nanocarbon framework derived from CNF can not only induce the CoFe nanoparticels into a well-aligned arrangement to fully expose active sites, but also promote the transfer of electrons remarkably, providing a versatile platform for the structural design and a novel strategy to boost OER activity.