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 IrO 2, Ir/C, Ru/C, and Pt/C. The most active catalysts presented η 10 at 400 and 359 mV toward the OER and HER, respectively, and η 0.5 at 390 mV for the ORR. These hybrid catalysts proved to sustain their activity even after 12 h of uninterrupted use.