Application of Sr₂FeMoO_6–δ-based medium entropy oxide as an anode internal reforming catalyst in solid oxide fuel cells fueled by low-concentration coal mine methane

Low-concentration coal mine methane (LC-CMM), which is predominantly composed of methane, serves as a clean and low-carbon energy resource with significant potential for utilization. Utilizing LC-CMM as fuel for solid oxide fuel cells (SOFCs) represents an efficient and promising strategy for its effective utilization. However, direct application in Ni-based anodes induces carbon deposition, which severely degrades cell performance. Herein, a medium-entropy oxide Sr₂FeNi_0.1Cr_0.3Mn_0.3Mo_0.3O_6–δ (SFNCMM) was developed as an anode internal reforming catalyst. Following reduction treatment, FeNi₃ nano-alloy particles precipitate on the surface of the material, thereby significantly enhancing its catalytic activity for LC-CMM reforming process. The catalyst achieved a methane conversion rate of 53.3%, demonstrating excellent catalytic performance. Electrochemical evaluations revealed that SFNCMM-Gd_0.1Ce_0.9O_2–δ (GDC) with a weight ratio of 7:3 exhibited superior electrochemical performance when employed as the anodic catalytic layer. With H₂ and LC-CMM as fuels, the single cell achieved maximum power densities of 1467.32 mW·cm^–2 and 1116.97 mW·cm^–2 at 800°C, respectively, with corresponding polarization impedances of 0.17 Ω·cm² and 1.35 Ω·cm². Furthermore, the single cell maintained stable operation for over 100 h under LC-CMM fueling without significant carbon deposition, confirming its robust resistance to carbon formation. These results underscore the potential of medium-entropy oxides as highly effective catalytic layers for mitigating carbon deposition in SOFCs.