Enhancing the performance of ammonia-fed intermediate temperature solid oxide fuel cells (IT-SOFCs) through the application of Ni₂MnGa Heusler alloy on the anode surface

The Radio Frequency (RF) sputtering process is used to deposit the Ni2MnGa Heusler alloy on the Ni-based Sm-doped CeO2 (Ni-SDC) anode surface. The peak power density (PPD) of the pristine Ni-SDC cell after 1 h NH3 feeding at 650 degrees C is 468.21 mW/cm(2), whereas with increasing time the PPD value continuously decreases and becomes 460.80 mW/cm(2) after 9 h. This decline in fuel cell performance is linked to Ni agglomeration and the formation of Ni3N on the anode surface. For 15 min alloy deposited cell, the PPD values increase with time and become 490.18 mW/cm(2) after 9 h on the same reaction conditions, which is quite high compared to that of pristine Ni-SDC. This improvement is attributed to the alloy's effectiveness in preventing Ni agglomeration and Ni3N formation, alongside accelerating the decomposition of NH3. However, Ni-SDC cells with longer alloy deposition times of 30 and 60 min showed lower PPD values compared to the pristine and 15-min deposited cells, indicating that extended deposition acts as a shield and reduces the active reaction surface area. Hence, a 15-min deposition of Ni2MnGa alloy shows the potential to improve fuel cell performance and preserve the stability of Ni-SDC at an intermediate temperature.