Laser upcycling of hemoglobin protein biowaste into engineered graphene aerogel architectures for 3D supercapacitors

Laser processing has emerged as a powerful and versatile tool for the synthesis and patterning of nanomaterials, offering high spatial resolution, material versatility, and digital control. In our recent work, we have developed a laser-based method for producing graphitic aerogels (GAs), or macroscale assemblies of nanometer-sized graphitic structures, by integrating principles of laser powder bed fusion with localized laser pyrolysis. Uniquely, this technique uses hemoglobin, a protein-rich biowaste derived from animal blood, as the precursor. Upon laser irradiation, the hemoglobin undergoes rapid thermal decomposition and in situ graphitization, forming 3D macroporous networks without the need for additional binders, templates, or harsh chemical treatments. Here we discuss the application of this process and materials to symmetrical 3D supercapacitors. The fabricated supercapacitors exhibit a high specific capacitance and excellent cycle stabilitys, attributable to the laser-engineered architecture facilitating ion diffusion even for thick electrodes.