Modification of coal as a fuel for the direct carbon fuel cell.

As a promising high-temperature fuel cell, the direct carbon fuel cell (DCFC) has a much higher efficiency and a lower emission as compared with conventional coal-fired power plants. To develop an increased understanding of the relationship between the microstructure, surface chemistry, and electrochemical performance of coal as a fuel for the DCFC, a coal sample from Central Queensland has been subjected to various pretreatments, including acid washing, air oxidation, and pyrolysis. It has been found that an acid treatment of the coal enhanced its electrochemical reactivity due to an increase in oxygen-containing surface functional groups. By contrast, heat treatment of the coal results in a sharp decrease in the electrochemical reactivity in the DCFC due to a decrease in the oxygen-containing surface functional groups, particularly CO(2)-yielding surface groups. A higher surface area of coal may also be helpful, but much less important than surface chemistry.