In situ growth of CoP on nickel foam for peroxymonosulfate activation via non-radical pathways in rhodamine B degradation

Transition metal-based materials have emerged as a promising catalyst for peroxymonosulfate (PMS) activation in pollutant removal. However, challenges such as nano-material agglomeration, high metal ion leaching, and low reactive oxygen species (ROS) yield still hinder their practical application. In this work, the CoP/NF successfully was synthesized to tune PMS activation from a radical pathway to a non-radical dominated pathway for efficient degradation of organic pollutants. The incorporation of phosphorus element modulated the cobalt-based catalyst surface charge state and induced local charge density, facilitating the catalytic activity. Consequently, at optimal conditions (catalyst = 1.5 cm², PMS = 0.3 g/L), CoP/NF achieved nearly complete removal of 40 mg/L rhodamine B (RhB) within 2 min over a wide pH (3.0–9.0), and maintained a strong anti-interference capacity for NO₃⁻, PO₄²⁻, Cl⁻. Furthermore, the degradation efficiency of RhB in the CoP/NF + PMS system remained 98 % even after 5 cycles. Impressively, ROS trapping and electron spin resonance (EPR) analyses revealed that the degradation process was dominantly driven by superoxide radicals (O₂^•–) and singlet oxygen (¹O₂), which served as the key mechanism for the CoP/NF + PMS system. This work provided further insights into tuning PMS activation pathway via the integration of metal phosphides growth on nickel foam for sustainable water treatment.