Hybrid of g-C3N4 Assisted Metal-Organic Frameworks and Their Derived High-Efficiency Oxygen Reduction Electrocatalyst in the Whole pH Range.

Abstract

A highly active electrocatalyst in the whole pH range for oxygen reduction reaction (ORR) is produced by employing the g-C3N4 assisted metal-organic frameworks (MOF) of C3N4@NH2-MIL-101 as the precursor. By pyrolyzing the hybrid at 700 °C, the C3N4@NH2-MIL-101 could be easily transformed into an abundant iron and nitrogen codoped porous carbon skeleton. The selective use of g-C3N4 as a support template plays a critical role in facilitating the formation of the architecture with high surface area and rich N content. The obtained catalyst of C3N4@NH2-MIL-101-700 manifested remarkable oxygen reduction activity over the pH 0-14. Noteworthy, the catalyst displayed outstanding ORR activity with more positive half-wave potential than that of the commercial Pt/C catalyst in both alkaline and neutral conditions. Additionally, the optimal C3N4@NH2-MIL-101-700 also exhibited prominent ORR activity which is almost equal to that of commercial Pt/C in acidic electrolyte with high selectivity and very low H2O2 yield. Most importantly, the better methanol tolerance and much higher stability than the commercial Pt/C of C3N4@NH2-MIL-101-700 no matter under alkaline, neutral, or acid conditions further demonstrate the catalyst to be a promising candidate for practical electrocatalytic applications.