A universal strategy of constructing Cr-NiFe MOF/CMC aerogel composite catalysts for efficient oxygen evolution reaction

Metal-organic framework (MOF)-based aerogel composites display extensive applications in fields such as catalysis, chemicals, separation and biology due to their high specific surface area, tailored structure and component features. The combination of a MOF structure in the brittle powder crystal state onto a flexible multilayer aerogel carrier can result in the exposure of a greater number of active sites, thereby greatly accelerating the mass transfer rate and enhancing the catalytic activity. Herein, we propose a universal low-temperature sol-gel method to synthesize a composite of NiFe MOF on carboxymethyl cellulose (CMC) aerogel. The proposed methodology is characterized by its gentleness, low cost, and universal applicability. Moreover, the catalytic activity of NiFe MOF was greatly enhanced by Cr doping. As a result, a 10% Cr-NiFe MOF/CMC aerogel composite exhibits a low oxygen precipitation overpotential of 235 mV and a low Tafel slope of 53.7 mV dec⁻¹ at a current density of 10 mA cm⁻², as well as displaying continuous cycling stability for more than 210 h. Its catalytic activity and good corrosion resistance are comparable with those of reported noble metal catalysts and are even superior to those of most reported Ni- and/or Fe-based catalysts. This work demonstrates the promising potential of MOFs/CMC aerogel composites in the development of highly effective electrocatalysts.