Energy-Efficient, Sustainable Cascade Glucose Electrooxidation into Glucaric Acid.

Abstract

Glucaric acid (GRA) is a critical platform chemical for manufacturing biodegradable materials. Selective glucose (GLU) electrooxidation into GRA provides a sustainable route for biomass valorization. However, conventional methods suffer from energy-intensive processes due to excessive operational potential exceeding 1.2 V. Here we demonstrate an energy-efficient tandem system that decouples GRA electrosynthesis into cascade GLU-to-gluconic acid (GNA) and GNA-to-GRA oxidation. When pairing an Au/C catalyst for selective aldehyde oxidation and an AuPt/C catalyst for hydroxyl oxidation, we achieve 91.8% Faradaic efficiency and nearly 100% conversion efficiency at 0.6 V_RHE for GLU-to-GNA oxidation, and 81% Faradaic efficiency and 90% conversion efficiency at 0.55 V_RHE for GNA-to-GRA oxidation. Chronoamperometry demonstrates ∼100% substrate conversion with a minor decrease in product selectivity, confirming the catalyst's excellent stability. Our tandem system improves the overall GLU-to-GRA energy efficiency from 13.8% for conventional one-step route to 31.8%. When oxygen reduction is selected as paired reaction, our system not only enables efficient chemical electrosynthesis, but is also estimated to generate electricity of 1.24 × 10⁵ kWh per kiloton GRA, outperforming traditional method with energy consumption of 4.31 × 10⁵kWh. Our work establishes a sustainable and economically viable pathway for biomass valorization, offering a blueprint for circular, carbon-neutral chemical production.