Carbon-Capped Zerovalent Nickel and Cobalt Nanoparticles as Multitask Hybrid Electrocatalysts

To attend to the worldwide need for clean energy technologies, multifunctional hybrid catalysts based on zerovalent metal nanoparticles protected by N-doped carbon matrices were developed. A cost-effective and scalable sol–gel process is used, in which metal ions coordinated to melamine-formaldehyde resins are the precursors. The carbon-capped zerovalent Ni/Co nanoparticles have metal content ranging from 43 to 63 wt % and N-doped carbon with the N/C ratio between 3% and 20%. It was found that the as-prepared or postmodified hybrid materials can catalyze the three most important electrochemical processes for hydrogen and fuel cell technology (oxygen evolution reaction, hydrogen evolution reaction, and oxygen reduction reaction; OER, HER, and ORR). For these three reactions, the carbon-capped zerovalent Ni/Co nanoparticles have comparable, or better, activity and stability in comparison to state-of-the-art noble metal catalysts as IrO2, Ir/C, Ru/C, and Pt/C. The most active catalysts presented η10 at 400 and 359 mV toward the OER and HER, respectively, and η0.5 at 390 mV for the ORR. These hybrid catalysts proved to sustain their activity even after 12 h of uninterrupted use.