Facile synthesis of tin-doped mayenite electride composite as a non-noble metal durable electrocatalyst for oxygen reduction reaction (ORR)

In this study, we synthesized nanosized Sn-doped C12A7:e- (C12Al7-xSnx:e-, where x = 0.20 to 1) composite with high surface area of 244 m2 g-1. An increasing trend in conductivity of Sn-doped C12A7:e- composites was observed at 300 K: 24 S cm-1, 68 S cm-1, 190 S cm-1 and 290 S cm-1, at doping levels of x = 0.20, 0.40, 0.80, and 1, respectively. Sn-doped C12A7:e-, with and without reduced graphene oxide (rGO), acts as a less expensive and highly active and durable electrocatalyst in the oxygen reduction reaction (ORR) for fuel cells. In the case of C12A7-xSnx:e- (where x = 1), calculated onset potential and current density were comparable to the commercially available 20% Pt/C electrode. Moreover, significant improvement was observed for Sn-doped C12A7:e- (doping level x = 1) with rGO composite. The ORR current density was about 5.9 mA cm-2, which was higher than that of Pt/C (5.2 mA cm-2). Our investigation of the effect of cation doping on structural and electrical properties of Sn-doped C12A7:e- composites shows that these results manifested the feasibility of this sol-gel method for different element doping. Furthermore, the as-prepared promising non-noble metal catalysts (NNMCs), viz., Sn-doped C12A7:e- composite materials, possess intrinsic long-time stability and excellent methanol resistance toward ORR in alkaline media and may serve as a promising alternative to Pt/C materials for ORR in its widespread implementation in fuel cells.