La2Ce2O7: A promising proton ceramic conductor in hydrogen economy

La2Ce2O7 (LDC) with cubic fluorite crystal structure was developed as a promising proton conductor material in hydrogen economy. In this critical review, we briefly introduced the current development of proton conductors and provided the advantage of LDC over other proton conductors. We also stated the possible crystal structure of LDC and intuitively interpreted the proton transfer mechanism between LDC lattices. The current applications of LDC in Solid Oxide Fuel Cells (SOFCs), hydrogen separation, polymer proton exchange membrane and ammonia synthesis were discussed in detail.