PNNL

Abstract

Electrochemical synthesis of high-value chemicals using renewable electricity could lead to sustainability advantages over conventional chemical manufacturing. The tight coupling between paired anodic and cathodic reactions in conventional electrochemical processes, however, constrains the products and efficiency that may be obtained from such processes. Here, we demonstrate a new strategy to achieve modular electrochemical synthesis (ModES) of different chemicals by decoupling the oxidative and reductive half-reactions and pairing them with a heterogeneous redox reservoir (RR). Specifically, sodium nickel hexacyanoferrate (NaNiHCF) is shown to serve as a robust and reversible RR that enables the modular production of two strong oxidants, hydrogen peroxide (H2O2) and sodium persulfate (Na2S2O8), via O2 reduction and sulfate oxidation in separate RR-coupled electrochemical processes. The excellent performance and operational stability of this system is demonstrated by continuous operation over 100 cycles (~36 h) to produce H2O2 and Na2S2O8 with high voltage efficiency. The concept presented here highlights the prospects for using RRs to enable efficient, modular, and on-demand electrochemical synthesis of valuable chemicals.