In situ formation of MnO 2 /Ni(OH) 2 @nickel foam with porous architecture for triggering persulfate-based advanced oxidation process

MnO 2 /Ni(OH) 2 was grown in situ on three-dimensional nickel foam (NF), which was then used to activate potassium persulfate (PS) for orange II (OII) degradation. The structure and morphology of the prepared materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The removal efficiency of OII was 98.68% with MnO 2 /Ni(OH) 2 @NF/PS system in 40 min. The three-dimensional hierarchical structure of mesoporous material promoted the efficient and fast electron transfer during catalytic activity. Based on classical quenching experiments and the electron spin resonance (ESR) experiments, ·OH and SO 4 •− were identified as the active species in MnO 2 /Ni(OH) 2 /NF/PS system for OII degradation and a degradation mechanism was proposed for this system. Compared with traditional micro-nano particle catalysts, 3D MnO 2 /Ni(OH) 2 @NF has the advantages of convenient recovery and good stability. MnO 2 /Ni(OH) 2 @NF catalyst could be recycled for at least three times, and the degradation rate was 89.06% after three cycles. This MnO 2 /Ni(OH) 2 @NF is expected to be used as a green heterogeneous catalyst.