Tuning Electron Density Endows Fe_1-CoP with Exceptional Capability of Electrooxidation of Organic Pollutants

The good performance of base metal catalysts for the electrooxidation of organic pollutants has attracted great attention. However, base metal phosphides for electrooxidation are seldom studied owing to the sluggish water adsorption and dissociation dynamics, which will hinder the production of the sorbed hydroxyl radicals (M(^•OH)) and thus inhibit the electrooxidation of organic pollutants. Herein, we proposed a universal strategy to improve the electrooxidation capability of metal phosphides by modulating the surface electron densities. The electron interactions between cobalt (Co) and phosphorus (P) are modulated after iron doping, resulting in more positively charged Co and more negatively charged P, which can promote the adsorption and activation of water molecules and produce large quantities of M(^•OH). Meanwhile, the experimental results show that the iron-modulated Fe_0.53Co_0.47P nanosheet arrays exhibit higher removal efficiency of tetracycline than the boron-doped diamond and Pt anode at low current intensity. Based on experimental results and density functional theory + U calculations (DFT + U), it is found that Fe_0.53Co_0.47P has lower barrier (0.45 eV) to form the sorbed hydroxyl radicals (M(^•OH)) and higher overpotential to produce O₂ than its counterparts, suggesting that Fe_0.53Co_0.47P can produce more M(^•OH) instead of O₂. The above results highlighted the feasibility of these base metal phosphides for electrooxidation for advanced water purification.