Coordination environment engineering of MoS 2-based nanocomposite by Ni atom incorporation for enhanced peroxymonosulfate activation

Ni-doped MoS 2 can activate PMS effectively to degrade organic pollutants because the Ni doping can modulate the adsorption energy barrier of MoS 2 to PMS molecule. However, how the coordination environment between Ni and MoS 2 affects the activation of PMS to generate active species is poorly understood. In this paper, Ni substitutional or Ni adsorptive doping of MoS 2 supported on TiO 2 /N-doped carbon nanofibers (designated as Ni sub -MTC or Ni ads -MTC, respectively) were synthesized and used as PMS activators to degrade tetracycline (TC), respectively. In the case of Ni ads -MTC that the Ni atoms adsorb atop of S vacancies in MoS 2 , the reaction kinetic constant for TC degradation can reach 0.3381 min -1 within 10 min in Ni a d s -MTC/PMS/Vis system. That is 1.84 times higher than that in Ni su b -MTC/PMS/Vis system (0.1835 min -1 ), where the Mo sites in MoS 2 are substituted with Ni atoms. This possibly due to that the Ni adsorptive doping can improve the regional activity of Mo -S bonds, which is more efficient than increasing the S vacancies by Ni substitutional doping. DFT calculations further support that the lower adsorption energy barriers of PMS were obtained on Ni adsorptive doping MoS 2 . Moreover, the main active species and possible TC degradation pathways were proposed. This work provides a new insight for designing metal doped heterogeneous catalysts with suitable coordination environments to improve PMS activation efficiency.