Green supercapacitor patterned by synthesizing MnO/laser-induced-graphene hetero-nanostructures on wood via femtosecond laser pulses

Eco-friendly next-generation energy storage devices with high energy density are required to meet the increasing demand for sustainable and green electronics. However, their manufacturing requires a lot of chemical precursors and is usually accompanied by chemical waste; it also involves laborious and time-consuming processes such as mixing, heat treating, casting, and drying. Here, we proposed that mass production of microsupercapacitors (MSCs) for green electronics can be achieved by embedding manganese monoxide (MnO) on wood-derived laser-induced-graphene (LIG) via femtosecond laser direct writing (FsLDW) technique. The direct synthesis of MnO/LIG hetero-nanostructures on wood was realized by drop-casting a small amount of precursor between the first and second FsLDW. The preceding FsLDW thermochemically converted wood into LIG while the following FsLDW converted the precursor into MnO, resulting in MnO/LIG hetero-nanostructures. As-fabricated MnO/LIG MSC exhibited enhanced areal capacitance (35.54 mF cm−2 at 10 mV s−1) and capacitance retention (approximately 82.31