Activation of hydrogen peroxide by molybdenum disulfide as Fenton‐like catalyst and cocatalyst: Phase‐dependent catalytic performance and degradation mechanism

Molybdenum disulfide (MoS2) has attracted great attention in hydrogen peroxide (H2O2) activation as a Fenton-like catalyst and cocatalyst, but the distinct mechanism of generating •OH remains unclear. In this paper, the metallic 1T phase and semiconducting 2H phase of MoS2 nanosheets were prepared and applied in MoS2/H2O2 and MoS2/Fe2+/H2O2 systems with and without light irradiation. Compared with 2H-MoS2, 1T-MoS2 exhibited superior removal rates in degrading organic pollutants in the two systems under light irradiation. However, the phase had little effect on activating H2O2 in the MoS2/H2O2 system under dark conditions. This is because it was difficult for the surface •OHads generated in the MoS2/H2O2 system to diffuse into solution, while the •OHfree radicals were mainly responsible for degrading organic pollutants. When introducing light irradiation, external energy may accelerate the desorption of •OHads into •OHfree. Interestingly, the conversion between Mo4+ and Mo5+ triggered the decomposition of H2O2 in the Fenton-like reaction, while the cycle of Mo4+/Mo6+ promoted the regeneration of Fe3+ when employing 1T-MoS2 as a cocatalyst. Meanwhile, the 1T-MoS2 catalysts exhibited excellent stability and ability to degrade various organics in the two systems. This work offers deeper insight into the MoS2-based Fenton-like and cocatalytic mechanisms.