Electrochemical hydrogenation of biomass substrates with cation shuttling in a solid electrolyte reactor.

Electrochemical hydrogenation of biomass-derived substrates offers a sustainable route to valuable chemicals, yet conventional systems often struggle to simultaneously achieve high efficiency and high product purity. Here we report an electrochemical process based on a porous solid-electrolyte reactor that integrates efficient hydrogenation with intrinsic purification for biomass-derived substrates, thereby eliminating the need for supporting electrolytes. The system promotes the hydrogenation of maleic acid solution (a model unsaturated biomass substrate) into succinic acid (a model saturated biomass substrate), via a cation shielding effect while suppressing competing reactions such as hydrogen evolution. By continuously recycling the generated sodium succinate from the cathode to the middle layer, the reactor further converts it into pure succinic acid, establishing a closed-loop alkali-metal-cation shuttle that enhances selectivity and minimizes side reactions. This system delivers succinic acid Faradaic efficiencies ~ 85%, long-term operational stability (over 500 hours), and a final solution of > 98% purity, without downstream electrolyte recovery. These results highlight a scalable pathway toward cleaner, more efficient electrochemical upgrading of biomass.