Biomass-Derived Inks with Tailored Pteridine Derivatives for Sustainable Printed Micro-Supercapacitors

Using biological redox compounds holds great potential in designing sustainable energy storage systems, but it is essential for structure optimization of biological redox centers and in-depth studies regarding their underlying energy storage mechanisms. Herein, a molecular simplification strategy is proposed to tailor the redox unit of pteridine derivatives, an essential component of ubiquitous electron transfer proteins in nature. The tailored pteridine derivatives can be combined with biomass holey graphene (BHG) to fabricate an ink with a micrometer-scale resolution for printing flexible electrodes for micro-supercapacitor (MSCs). The reversible tautomerism of pteridine derivatives from alloxazinic to isoalloxazinic structure is first unveiled in supercapacitors. Through molecular tailoring, printed MSC electrodes using pteridine derivatives/BHG ink demonstrate excellent charge storage, outstanding areal capacitance (95.3 mF cm⁻² at 0.1 mA cm⁻²), energy density (16.3 µWh cm⁻²), power density (208 µW cm⁻²), long-term cycling performance (90.5% retention after 10 000 cycles), easy integration, and exceptional flexibility (maintaining capacitance at various bending states). The non-covalent interaction of tailored pteridine molecules with redox centers and biomass porous graphene suggests a mature screen-printing technology for fabricating a sustainable energy storage system with a rational MSC configuration.