Phytogenic Self-Conducting Flash Joule Heating Converts Rare-Earth Hyperaccumulator Biomass into Graphene Composites with Minimized Life-Cycle Impacts

Rare-earth elements (REEs) are essential to clean-energy technologies, yet their extraction remains energy intensive and environmentally damaging. Although REE hyperaccumulator plants offer sustainable bioresource, their conversion into functional materials is inefficient and poorly developed. Here, we report a feedstock-customized phytogenic self-conducting flash Joule heating (PSC-FJH) strategy that directly converts REE hyperaccumulator plants into CeO2-graphene electrocatalysts within seconds, without external conductive additives or energy-intensive pretreatment. The low-temperature FJH (∼600 °C, 1.4 s) first forms conductive biochar, enabling subsequent high-temperature FJH (∼2600 °C, 0.4 s) that induces graphene formation and simultaneous in situ oxidation of endogenous Ce to uniformly dispersed CeO2 particles. The resulting CeO2-graphene exhibits oxygen reduction reaction activity, surpassing that of commercial carbon black. Life-cycle assessment shows that PSC-FJH reduces energy consumption by over 70% compared with conventional graphitization processes. This work integrates ecological phytomining with ultrafast carbon conversion to upgrade REE hyperaccumulator plants into high-value catalytic materials.