Coal pretreatment and Ag-infiltrated anode for high-performance hybrid direct coal fuel cell

Hybrid direct coal fuel cells (HDCFCs) have the potential to convert coal into electrical power in a clean and efficient manner. However, the related coal pretreatment method and the anode activity should both be improved, before the HDCFCs could match the performance of other direct coal fuel cells such as those based on solid oxide. In this study, we pyrolysed bituminous coal at 800 °C followed by modification with acetic acid, in order to remove organic volatiles and reintroduce surface functional groups, respectively. The result was a modified char that was highly pure and with high oxidation activity. Further, the Ni-(Y₂O₃)_0.08(ZrO₂)_0.92 anode was infiltrated with Ag nanoparticles as an effective catalyst to promote the electro-oxidation of carbon. Under optimised conditions, the HDCFC with Ag-infiltrated anode and modified char as fuel demonstrated a maximum power density (403 mW cm⁻² at 750 °C) that exceeds previous results for coal-based fuels. The cell also showed stable operation for 14 h, with a fuel conversion of 97.22% and Faradic efficiency of 61.06% using 0.4 g modified char.