From Waste to Wonder: Food Waste‐Derived Hydrothermal Carbon Powers H 2 O 2 Photosynthesis for Sustainable Farming

The valorization of food waste (FW) into functional carbon materials offers a promising strategy for simultaneously mitigating environmental burdens and promoting resource recovery. Herein, N,S‐co‐doped hydrothermal carbon materials (N,S‐HTC and N,S‐HTC‐W) are fabricated from FW via H 2 SO 4 ‐assisted hydrothermal carbonization. Spectroscopic analyses reveal that hydrothermal carbonization reinforces the π‐conjugation carbon framework and effectively incorporates N and S heteroatoms, yielding n ‐type semiconductors with well‐aligned band structures. N,S‐HTC exhibits a high carbonization degree and improved charge‐carrier dynamics, which enables efficient photocatalytic oxygen (O 2 ) reduction at a hydroperoxide (H 2 O 2 ) production rate of 22.59 mmol·L −1 ·g cat. −1 ·h −1 with 51% selectivity via a successive single‐electron pathway. Crucially, N,S‐HTC demonstrates outstanding robustness in cycling and long‐term tests and sustains H 2 O 2 production even under oxygen‐deficient conditions. Under simulated wheat cultivation scenarios, 0.08 mmol·L −1 H 2 O 2 is achieved outdoors under natural sunshine using only dissolved atmospheric oxygen, sufficient to alleviate copper‐induced growth inhibition in wheat. Simultaneously, nutrient profiling and heavy‐metal assessment confirm that the FW‐derived HTC materials satisfy agronomic and environmental safety requirements for soil amendment. Overall, this work proposes a practical circular‐economy paradigm that upgrades FW into a dual‐function carbon material capable of improving soil quality while enabling on‐site solar‐driven H 2 O 2 production for crop growth promotion and abiotic stress mitigation.