Phosphidation of Cu²⁺ Ions Loaded HKUST-1 to Derive Cu₃P/C Nanomaterials for Electrocatalytic Carbon Dioxide Reduction

Developing effective electrocatalysts for the conversion of CO2 to CO is essential for enhancing the global carbon cycle. In this article, we report the synthesis of Cu3P/C nanomaterials, derived from the copper-based MOF (HKUST-1), using a novel phosphidation method. To enhance the copper contents in the final material, HKUST-1 is impregnated in Cu2+ solutions of various concentrations, followed by phosphidation. Cu3P nanoparticles fully embedded in hierarchical carbon have been confirmed by using transmission electron microscopy. These nanoparticles exhibit remarkable efficiency in the reduction of CO2 to CO. Among the various synthesized electrocatalysts, the optimal electrocatalyst, i.e., (5 M) Cu3P/C demonstrates outstanding performance, which shows 88% Faradaic efficiency for CO production. It also demonstrates a low overpotential (η) of only 177 mV, a high current density (j) of 60 mA cm–2, and long-term stability over 20 h at various potentials in 0.1 M KHCO3 medium, making it an excellent choice for CO2 reduction applications. The catalyst’s exceptional selectivity for converting CO2 to CO is further validated by qualitative detection of CO using the PdCl2 strips method.