Upgrading pomelo peels into laser-induced graphene for multifunctional sensors

Converting waste pomelo peels into high value-added products is highly desirable both economically and environmentally. Although pomelo peels can be upgraded into carbon materials by direct pyrolysis or hydrolysis, these pyrolysis methods require stringent conditions or cumbersome procedures. In this work, we developed a simple and efficient method based on direct laser writing (DLW) technology to upgrade pomelo peels into high value-added laser-induced graphene (LIG) with a yield of about 30 wt%. The upgraded LIG exhibits good properties such as a porous structure and a high conductivity. Multifunctional sensors were fabricated by coating LIG electrodes with sensing materials for detecting light, humidity, and phosphate. Owing to the good properties of the upgraded LIG, the sensors displayed decent sensing performances. This work offers a potential solution for transforming agricultural waste into high-value-added products in a simple and efficient way.