Enhanced heterogeneous catalytic ozonation to degrade p-nitrophenol by Co-doped Ni₃S₂/NF nanosheets

In this study, a cobalt-doped nickel disulfide (Co-Ni₃S₂) catalyst was prepared by a one-step hydrothermal method, which was grown on the surface of firm and dense three-dimensional porous nickel foam (NF). Although researchers have conducted extensive research on heterogeneous catalytic ozonation (HCO) over the past decades, the development of highly efficient, easily separable, stable, and recyclable HCO catalysts is still a bottleneck for practical applications. Taking p-nitrophenol (PNP) as the targeted pollutant, the synergistic effect of Co-Ni₃S₂/NF composites and ozone was studied. The results show that Co-Ni₃S₂/NF with different doping ratios can degrade PNP by more than 99% within 40 minutes, showing high activity. At the same time, in the cycle experiment, Co-Ni₃S₂/NF showed good stability and recyclability compared with the powder catalyst and therefore, the former could reduce water treatment cost. We also found that in the Co-Ni₃S₂/NF/O₃ system, the production rates of ¹O₂, •OH and O₂^•- can be greatly improved, and the process of degradation is synergistic with both non-radicals and free radicals.