AC magnetic field enhancement oxygen evolution reaction of bimetallic metal-organic framework

摘要

Cost-effective oxygen evolution reaction (OER) electrocatalysts play a key role in electrocatalytic water splitting process. Here, a facile and scalable strategy was applied to synthesize the bimetallic metal-organic frameworks (MOFs) with high OER activity, and the effects of AC magnetic field on OER was also investigated. Results shows that the bimetallic MOFs (Co0.4Ni0.6-MOF-74) exhibited a three-dimensional flower-like morphology, and possessed a higher BET specific area of 905.39 m(2) g(-1) as well as a smaller median pore size of 0.49 nm as compared to single metal MOFs; It owned a lowest overpotential of 314 mV at 10 mA cm(-2) and Tafel slope of 79.39 mV dec(-1), both are much lower than these of single metal MOFs, being due to the high specific area and more active sites derived from the distorted crystal structure; When AC magnetic field strength equaled to 5.50 mT, over potential at 10 mA cm-2 for Co0.4Ni0.6-MOF-74 reached minimum value of 201 mV, reduced by about 36 as compared to that without magnetic field, indicated that AC magnetic field could greatly improve OER process. These improvements resulted from the spin polarization effect, magnetohydrodynamic (MHD) convection and improved active point temperature. (C) 2022 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.