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

Abstract

In this study, we synthesized nanosized Sn-doped C12A7:e⁻ (C₁₂Al_7−xSn_x: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 C₁₂A_7−xSn_x: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.