Yeast-derived phosphorus for eco-friendly synthesis of Cu₃P/biochar catalysts with enhanced hydrogen peroxide-based Fenton-like reaction

Transition metal phosphides (TMPs) are promising catalysts, yet challenges remain in terms of low stability and secondary pollution. Herein, we report a novel synthesis of Cu₃P particles loaded on yeast-derived biochar (Cu₃P/BC) using Cu²⁺ as a precursor and mannan-phosphate from yeast cell walls as a sustainable phosphorus source. Cu₃P/BC demonstrated a significantly superior catalytic performance in Rhodamine B (RhB) degradation, exhibiting a 25.2-fold increase in RhB removal efficiency and an approximately 4-fold increase in chemical oxygen demand removal efficiency compared to biochar alone. Furthermore, the catalytic Fenton-like performance remained robust, achieving degradation efficiencies between 70.7 % and 88.6 % across three different real water matrices, highlighting the catalyst's potential for practical applications. Stability tests revealed effective performance over four cycles, and post-regeneration, the removal rate increased to 96.4 %, with copper leaching ≤0.51 mg/L. Free radical quenching experiments and electron paramagnetic resonance analysis revealed that reactive oxygen species, •OH, O₂•^-, and ¹O₂, played critical roles in the degradation of RhB. These reactive species were primarily generated through the redox cycling of Cu(II)/Cu(I), a process that facilitated H₂O₂ activation. Moreover, toxicity assessments indicated that while early intermediates show moderate toxicity, extended reaction times promote complete mineralization into non-toxic end products. This study offers a facile, eco-friendly method for fabricating TMP/carbon composites from yeast biomass, with significant potential for wastewater treatment.