Ultrathin Nanobelts as an Excellent Bifunctional Oxygen Catalyst: Insight into the Subtle Changes in Structure and Synergistic Effects of Bimetallic Metal-Organic Framework

In recent years, increasing attention has been paid to metal-organic frameworks by scientists working in the field of electrocatalytic material chemistry. Herein, using the hydrothermal method, ultrathin Ni/Co bimetallic metal-organic framework nanobelts that can be directly adopted as highly efficient electrocatalysts are prepared. The optimized Ni/Co ultrathin nanobelts can reach an onset potential of 0.939 V [these values are very close to those of Pt/C (0.940 V)] and show superior stability relative to that of Pt/C toward oxygen reduction reaction (ORR). Additionally, under the current density of 10 mA cm(-2), the Ni/Co ultrathin nanobelts show the potential of 1.478 V for oxygen evolution reaction (OER), which is much better than that of IrO2, indicating the large potential of the metal-organic frameworks as a bifunctional oxygen catalyst in metal-air batteries. In addition, after OER and ORR, the color of the Ni/Co ultrathin nanobelts sample is slightly lighter, and it can be seen that the channel becomes blurred but still exists. The X-ray diffraction, infrared spectrometry, and X-ray photoelectron spectroscopy results for Ni/Co ultrathin nanobelts before and after catalysis are basically identical. The findings suggest that the ultrathin belt-like structure and the synergy effect between Ni and Co are crucial for tuning the electrocatalytic activity.