Self-assembling of versatile Si3N4@SiO2 nanofibre sponges by direct nitridation of photovoltaic silicon waste

Abstract

Solar cells based on crystalline silicon wafers have dominated the global photovoltaic market for many years. Unfortunately, a large amount of photovoltaic silicon waste (PSW) also was produced during the process of cutting silicon ingot into silicon wafer. The improperly discarded PSW will bring about serious environmental hazardous problems, so it is highly necessary to safely and effectively recover and utilize PSW. Here, we report self-assembled 3D Si3N4@SiO2 nanofibre sponges utilising PSW as silicon sources for the first time. This kind of ceramic sponge displays excellent compression resilience under a maximum strain of 67% due to the flexibility of the Si3N4@SiO2 nanofibres. The Si3N4@SiO2 nanofibre sponges can withstand high temperatures beyond 1200 °C with negligible weight loss and demonstrates favourable thermal insulation properties. Furthermore, the porous Si3N4@SiO2 nanofibre sponges possess ultra-low dielectric properties, with the minimum dielectric constant and dielectric loss approaching 1 and 0, respectively. In short, a simple and low-cost technology using industrial waste to fabricate versatile Si3N4@SiO2 nanofibre sponges with prominent performance is of great significance for the development and application of 3D ceramic architectures in various industry fields including aerospace, electronic devices and thermal insulation.