Photocatalytic production of H2O2 and its in situ utilization over atomic-scale Au modified MoS2 nanosheets

Au modified MoS2 nanosheets (Au@MoS2) for photocatalytic production of H2O2 were prepared via a simple pathway including the deposition-reduction and immobilization process by using a low dosage of an Au source. Nanoparticles smaller than 1 nm and single atoms, as two major forms of Au, were found to be widely dispersed on the surface of MoS2 and captured by its lattices. Au modification brought out the low recombination rate of e(-)-h(+) pairs, long lifetime of electrons, and more negative flat band potential for MoS2. Au@MoS2 achieved efficient photocatalytic production of H2O2 from H2O and air in the absence of pure O-2 and organic electron donors. An optimal catalyst loading 0.50 wt% of Au enhanced the H2O2 productivity by about 2.5 times from bare MoS2. A significant finding was that higher pH was beneficial to H2O2 synthesis, and the H2O2 productivity at pH 9 was further enhanced 7.4 times from that at pH 2. Au@MoS2 was recycled more than five times without inactivation and obtained considerable 791.72 mu M of H2O2 under real sunlight irradiation for 6 h, exhibiting application potential. Mn2+ as the active center for Fenton-like reactions was doped in MoS2 nanosheets before Au-0 modification in order to use the photogenerated H2O2 in situ. Accordingly, a novel in situ Fenton process was proposed, and obtained significant degradation efficiencies for rhodamine B and methylene blue dyes, depending on the H2O2 productivity. Another important finding was that Mn2+ further increased H2O2 productivity by 2 times based on Au@MoS2. (C) 2019 Elsevier Inc. All rights reserved.