Phosphidation\nof\nCu<sup>2+</sup> Ions Loaded HKUST‑1\nto Derive Cu<sub>3</sub>P/C Nanomaterials for Electrocatalytic Carbon\nDioxide Reduction

Developing\neffective electrocatalysts for the conversion\nof CO<sub>2</sub> to CO is essential for enhancing the global carbon\ncycle.\nIn this article, we report the synthesis of Cu<sub>3</sub>P/C nanomaterials,\nderived from the copper-based MOF (HKUST-1), using a novel phosphidation\nmethod. To enhance the copper contents in the final material, HKUST-1\nis impregnated in Cu<sup>2+</sup> solutions of various concentrations,\nfollowed by phosphidation. Cu<sub>3</sub>P nanoparticles fully embedded\nin hierarchical carbon have been confirmed by using transmission electron\nmicroscopy. These nanoparticles exhibit remarkable efficiency in the\nreduction of CO<sub>2</sub> to CO. Among the various synthesized electrocatalysts,\nthe optimal electrocatalyst, i.e., (5 M) Cu<sub>3</sub>P/C demonstrates\noutstanding performance, which shows 88% Faradaic efficiency for CO\nproduction. It also demonstrates a low overpotential (η) of\nonly 177 mV, a high current density (j) of 60 mA cm<sup>–2</sup>, and long-term stability over 20 h at various potentials in 0.1\nM KHCO<sub>3</sub> medium, making it an excellent choice for CO<sub>2</sub> reduction applications. The catalyst’s exceptional\nselectivity for converting CO<sub>2</sub> to CO is further validated\nby qualitative detection of CO using the PdCl<sub>2</sub> strips method.