Boosting methanol electro-oxidation to formate by trace iron induced suppression of cobalt(IV) formation
Jialong Lin, Xinlin Wang, Bingxue Cheng, Ruize Zhou, Yuhang Li, Tamao Ishida, Guangli Xiu, Toru Murayama, M. C. Lin
Abstract
Converting methanol to high-value formate through electrochemical methods can significantly reduce the energy consumption associated with conventional production processes. In this study, we directly synthesized iron-doped cobalt phosphate (Fe-CoPO) on nickel foam (NF) to achieve excellent activity for the methanol electro-oxidation reaction (MOR). Our results demonstrated that Fe-CoPO produced a current density of 100 mA·cm<sup>−2</sup> at a significantly low operating potential of 1.436 V (vs. reversible hydrogen electrode (RHE)) and operated steadily for 16 h at this current density with a Faradaic efficiency (FE) of 97%. Furthermore, Fe-CoPO maintained a high FE of 100% even at an extremely high current density of 300 mA·cm<sup>−2</sup> for 8 h. We found that the high MOR activity of Fe-CoPO results from electrochemical reconstruction to generate the Co<sup>2+/3+</sup>–O bond. The heterogeneous interface between Fe and Co inhibits the formation of Co<sup>4+</sup>, which significantly enhances the MOR activity. Thus, this work not only provides insights into the mechanism of MOR over Co-based catalysts but also offers a novel direction for developing highly active MOR catalysts.