Blocking oxygen evolution reaction for efficient organic electrooxidation coupling hydrogen production by using layered double hydroxide rich in active oxygen.

Electrochemical hydrogen production coupling upgrading of organic substances has been regarded as a promising approach to harvest both green energy and commodity products. However, the competition of oxygen evolution reaction always limits the transformation of organics and the research on this mutually restricted relationship was less focused. Herein, an amorphous layered double hydroxide (LDH) rich in active oxygen is well-constructed, which realizes the glycerol oxidation with nearly 100 % faradaic efficiency and high formic acid production yield at a current density > 200 mA cm−2. In-situ monitoring combined with electrochemical probe confirms that the active oxygen on the amorphous LDHs promotes the deprotonation of glycerol. To further reduce the energy input, an alkaline-acid hybrid flow cell is built to achieve constant hydrogen production coupling formic acid production at high current density (100 mA cm−1) under an ultra-low cell voltage of 0.90 V with high durability for over 500 h. Moreover, a novel waste oil recycle path is developed to transform waste oil into target value-added products (potassium diformate (KDF) and biodiesel) and hydrogen fuels using the amorphous LDHs electrocatalysts. [Display omitted] • An amorphous layered double hydroxide (A-NiFe-LDH) rich in active oxygen was prepared via electrochemical amorphization. • A-NiFe-LDH can boost electrochemical glycerol oxidation coupling hydrogen production. • The existence of multiple active oxygen species (AOS) and AOS involved oxidation mechanism is uncovered. • A new cycling path of waste oil into target value-added products is designed. [ABSTRACT FROM AUTHOR]