<p>Solar-driven artificial photosynthesis of hydrogen peroxide and high-value chemicals from oxygen and biomass is promising but is hindered by poor light absorption, sluggish kinetics of biomass dehydrogenation, and low oxygen reduction selectivity. Herein, we develop a resorcinol-formaldehyde resin/carbon-supported Ta-N₂O₂ single-atom catalyst (RF/C-TaSA) that enables broad-spectrum light harvesting (&gt;&#xa0;932 nm) and selective biomass conversion in a solid-organic-aqueous three-phase system. RF/C-TaSA achieves a high 3.0% quantum yield at 635 nm, with Ta-N₂O₂ sites stabilizing intermediates and reducing the energy barrier for biomass conversion. We further demonstrate that RF/C-TaSA enables efficient artificial photosynthesis of H₂O₂ and value-added chemicals from more available thatch, pine needles and wastepaper. Combining catalyst innovation and system engineering, we build a solar-powered RF/C-TaSA-based photocatalytic device for directly producing commercially viable H₂O₂ at a high concentration of 3 wt% and high-value-added chemical without requiring energy-intensive separation processes for 70-day operation. Furthermore, the produced crude concentrated H₂O₂ can also be readily converted to solid H₂O₂ powder (Na₂CO₃ ∙ 1.5 H₂O₂) for ease of storage and transport with high sterilization activities even after 6 months.</p>