Surface reconstruction enabling MoO2/MoP hybrid for efficient electrocatalytic oxidation of p-xylene to terephthalic acid

Abstract

Selective oxidation of p-xylene (PX) to terephthalic acid (TA) remains exceptionally challenging since it easily undergoes deep oxidation. Herein, a nickel foam-supported molybdenum dioxide/molybdenum phosphide hybrid electrocatalyst (MoO2/MoP/NF) is reported for highly selective generation of TA via electrocatalytic oxidation (ECO) of PX in alkaline medium. The efficient MoO2/MoP/NF anode material displays a unique cluster-like nanocone architecture, showing abundant active sites and rapid charge transfer kinetics. Benefit from the synergy between MoO2 and MoP, the MoO2/MoP/NF provides a high TA selectivity of 94.8% and an outstanding faradaic efficiency of 76.9% at the conversion of 71.6%. Additionally, the anodic oxidation of PX over MoO2/MoP/NF promotes the cathodic hydrogen production. The potential-induced surface reconstruction of the as-synthesized MoO2/MoP/NF yields new phases of phosphomolybdate and potassium molybdate. The top P site on the phosphomolybdate surface facilitates the adsorption of reaction intermediates but weakens the adsorption of TA, thereby yielding high selectivity toward TA.