Performance and mechanism of hydrogen evolution from room-temperature thermal catalytic water splitting by α-phase Si3N4

Abstract

Because α-Si3N4 has a noncentrosymmetrical crystal pattern capable of self-polarizing point groups, it is theoretically pyroelectric. When the ambient temperature changes, the surface of a pyroelectric semiconductor will produce abundant compensationary charges q+ and q-, which theoretically can be used into hydrogen evolution from water splitting. In this study, the piezoelectric and pyroelectric performances of α- Si3N4were validated by piezoelectric force microscopy and potassium permanganate reduction experiments. Based on the pyroelectric performance of α- Si3N4 and with methanol as the sacrificial agent, hot–cold cycles were conducted from room temperature (27 °C) to 60 °C. Per gram of catalysts can produce 12.32 μmol/g hydrogen after 20 cycles, and the hydrogen yields after repeated experiments did not significantly decrease, proving that Si3N4 has high stability and that the pyroelectric effect is highly potential for hydrogen production from water splitting.