Plasma-Induced Surface Reconstruction of NiFe/Co3O4 Nanoarrays for High-Current and Ultrastable Oxygen Evolution and the Urea Oxidation Reaction

Low-cost and simple strategies to synthesize highly efficient and robust oxidative electrocatalysts for commercial large-scale water electrolysis are still a challenge. Here, we reported a reductive H 2 plasma surface modification strategy, where a defect-rich amorphous NiFe coating layer can be anchored and interact with porous Co 3 O 4 nanoarrays. The plasma-modified surface can promote the reconstruction process to generate high-valence and ultra-active species, thus forming abundant active centers and oxygen vacancies with high electrocatalytic activity. The H 2 –NiFe/Co 3 O 4 composite reveals excellent bifunctional electrocatalytic ability, and ultralow overpotentials of 233 and 273 mV are required to reach 100 and 1000 mA cm –2, respectively, for oxygen evolution, while the urea oxidation reaction (UOR) requires the potentials of 1.315 and 1.420 V to reach 10 and 1000 mA cm –2, respectively. The superior electrocatalytic stability is confirmed by a 240 h long-term test at 1 A cm –2 for the oxygen evolution reaction and the consecutive multistep chronoamperometric tests for the UOR. This work provides an easily scalable and energy-efficient surface modification method to fabricate a robust bifunctional catalyst, while the atomic species and configuration can also be flexibly adjusted, which is suitable to be extended to various application fields.