Rational design and insights into the synergistic activity of CeO_x and Zn on Cu₂Se for highly selective electrocatalytic methanol oxidation to formic acid

The selective methanol oxidation reaction (MOR) can produce formic acid, which is an important chemical intermediate in the textile, printing, and pharmaceutical industries. In this study, an amorphous/crystalline catalyst, Cu₂Se/(Zn)CeO_x, was obtained, which exhibited high selectivity for the MOR to produce formic acid. The synergistic effect of Zn, CeO_x and Cu₂Se in Cu₂Se/(Zn)CeO_x provides an internal driving force for the high availability of the active sites, which in turn maintains higher MOR efficiency. The leaching of Zn resulted in an elevated concentration of CeO₂ in the amorphous CeO_x, which functions not only as a charge transfer promoter but also as an initiator for the efficient regeneration of the active Cu²⁺ sites. In situ electrochemical impedance spectroscopy demonstrated that elevated methanol concentrations inhibit the phase transition of the catalyst to high-valent electrooxidation products. The findings of this study may provide new avenues for the exploration of the selective MOR to produce formic acid.