The In Situ Electrochemical-Chemical Cascade Strategy for Pyruvic Acid Synthesis.

Hydrogen peroxide (H2O2), as a green oxidizing medium, can be generated and utilized in situ via an electrochemical-chemical cascade, enabling organic transformations while enhancing efficiency and selectivity. However, balancing high H2O2 production, efficient activation, and selective substrate conversion remains challenging. Herein, a series of transition metal-doped CeO2 catalysts were developed for electrocatalytic H2O2 generation and its subsequent use in converting α-hydroxy acids to pyruvate. Among them, Ni-CeO2 exhibited the best performance, achieving a pyruvate production rate of 19.9 mmol g-1 h-1 and a Faradaic efficiency of 55.3%. Mechanistic studies revealed that transition metal doping regulates the local coordination environment and oxygen vacancy concentration, thereby optimizing the adsorption strength of the *OOH intermediate, which governs the two-electron oxygen reduction reaction pathway and H2O2 generation and release. Furthermore, in situ generated H2O2 was selectively activated on the catalyst surface to form a reactive oxygen species network dominated by hydroxyl radicals (·OH) and assisted by singlet oxygen (1O2). Among these, ·OH showed the lowest energy barrier for α-C─H bond activation and subsequent electron rearrangement, making it the key species for pyruvate formation. This work provides a new strategy for the preparation of value-added chemicals.