Columnar cobalt molybdate spinel rooted on three-dimensional nickel foam as robust catalyst for 4-nitrophenol degradation through peroxymonosulfate activation.

Abstract

Metal oxides-catalyzed peroxymonosulfate (PMS) activation systems show promise in decomposing organic pollutants, whereas the critical challenges such as catalyst aggregation and metal ion leaching significantly impact the stability and reusability of catalysts and thus limit widespread application. To address these issues, an effective self-supported three-dimensional PMS activator consisted of spinel cobalt molybdate (CoMoO₄) and nickel foam (NF) (CoMoO₄/NF) is fabricated through hydrothermal and annealing processes. The cooperative redox interaction between Co and Mo metal sites in CoMoO₄/NF play a crucial role in efficiently activating PMS to degrade 4-nitrophenol (4-NP). Specifically, the CoMoO₄/NF/PMS system achieves a 95% degradation rate for 4-NP within 35 min. Attributing to the unique columnar structure and strong connection between CoMoO₄ and NF, the catalyst/PMS system maintains high efficiency after five cycles. Furthermore, the system demonstrates broad applicability for degrading various organic pollutants and resistance to interference from different pH levels, inorganic anions, and humic acid. This study proposes radical/non-radical degradation pathways by identifying active species and investigates the degradation mechanism and toxicity of intermediate products for 4-NP. These findings offer valuable insights for designing and synthesizing self-supported catalysts to eliminate pollutants through PMS activation.