Recent advancement of solid oxide fuel cells towards semiconductor membrane fuel cells

In the last few decades, there has been remarkable progress in the development of solid oxide fuel cells (SOFCs) based on both traditional solid electrolyte materials and novel semiconductor membranes. However, limited attention has been given to the transition of SOFCs from oxide ion-based electrolyte membranes to semiconductor membrane devices, considering the overall perspective of materials, technology, and scientific principles. Traditional knowledge strictly dictates that semiconductors should not be used as the membrane unless these materials possess negligible electronic conduction. This is because semiconductor membrane materials typically exhibit significantly higher electrical conductivity, surpassing the inherent ionic conductivity. Interestingly, by using semiconductors as the membrane, numerous novel materials have been demonstrated in the literature, which seems difficult to understand from traditional SOFC knowledge. Therefore, there is an emerging need to summarize and explore new understanding and knowledge of materials, technology, and science of SOFCs and Semiconductor Membrane Fuel Cells and their transition. In this review, we attempted to summarize the gap between the current state of SOFCs and the advancements in new materials, technologies, scientific principles, and mechanisms driving the development of such devices.