Monolithic Z-scheme NiS2/In2S3@PDMS/NF gas diffusion photocatalyst with strong interfacial O2 accumulation effect for effective H2O2 production and Fenton demulsification

In this work, a monolithic NiS2/In2S3@PDMS/NF gas diffusion photocatalyst is elaborately designed and synthesized. The synergy of structure and component gives advantageous features to NiS2/In2S3@PDMS/NF, including hydrophobic hollow NiS2/In2S3@PDMS tubes and porous Ni foam for O2 confinement/enrichment, strong coupling Z-scheme heterointerface for electron-hole separation, and abundant active sites for H2O2 generation via dual-channel pathway. The monolithic NiS2/In2S3@PDMS/NF gas diffusion photocatalyst exhibits outstanding photocatalytic activity for H2O2 production in dichloromethane/water two-phase system, with a yield of 1435.4 μmol·gcat−1, which is 2.5 times higher than that of NiS2/In2S3@PDMS. This can be attributed to the synergistic effect of spatial confinement effect in hollow tubes, hydrophobic modification of catalyst surface and 3D porous breathable self-support substrate. Additionally, white solid H2O2 powder with strong oxidizing property is obtained for reducing costs and increase safety in storage and transportation. Then, a fast and universal smartphone-assisted colorimetric method is constructed to quantitatively detect H2O2 on-site. Besides, NiS2/In2S3@PDMS/NF also exhibits a remarkable demulsification effect on SDS-stabilized oil-in-water emulsion through photocatalytic-Fenton degradation of SDS with "Two Birds One Stone" strategy, which is important for petroleum industry and environmental remediation.