Dynamic attraction of leached metal species enables durable glucose electrooxidation in a strong acid

Abstract

Electrooxidation of organic compounds to produce organic acid in an acidic electrolyte can circumvent product acidification step with high cost in alkaline electrolyte. However, catalysts often suffer from low stability in acid owing to severe leaching. Herein, we report a strategy to dynamically attract leached metal species to stabilize catalyst in a strong acid. In electrooxidation of glucose to formic acid over a lead dioxide (PbO₂) catalyst, switching the electrolyte from HClO₄ to H₂SO₄ reduces Pb²⁺ leaching by up to 30 times. As a result, a 275-hour stable performance at 1 A cm^‒2 is achieved in H₂SO₄ (pH 0.3) using a membrane electrode assembly. Experimental evidence demonstrates that the SO₄²⁻ ion attracts the leached Pb²⁺—generated from chemical reduction of PbO₂ by glucose—by in-situ forming PbSO₄ precipitate on the electrode, which is then oxidized to the active PbO₂ phase. Benefiting from acidic electrolysis, we achieve raw cellulose conversion to formic acid without intermediate separation through an acid hydrolysis−electrolysis tandem process. This work demonstrates an efficient strategy to stabilize electrocatalysts that suffer from leaching issues in acidic conditions.