One-Step Interfacial Integration of Graphene Oxide and Organic Chromophores into Multicomponent Nanohybrids with Photoelectric Properties

Graphene Oxide/Zinc Phthalocyanine Selective Singlet Oxygen Visible-Light Nanosensor for Raman-Inactive Compounds

A novel phthalocyanine-based hybrid nanofilm is for the first time successfully applied as an oxidative platform for surface enhanced Raman spectroscopy (SERS) sensing to fine-resolve Raman-inactive compounds. The hybrid is formed by self-assembly of zinc(II) 2,3,9,10,16,17,23,24-Octa[(3',5'-dicarboxy)-phenoxy]phthalocyaninate (ZnPc*) with the solid-supported monolayer of graphene oxide (GO) mediated by zinc acetate metal cluster. Atomic force microscopy, UV-vis and fluorescence spectroscopies confirm that this simple coordination motive in combination with molecular structure of ZnPc* prevents contact quenching of the light-excited triplet state through aromatic stacking with GO particles. Fluorescence probing with Sensor Green and terephthalic acid as specific indicators of active oxygen intermediates shows that the hybrid nanofilm initiates selective singlet oxygen generation under visible light. Direct one-electron oxidation of tetramethylbenzidine (TMB) (1.0×10-7 m) on the hybrid surface in the presence of 100 nm silver nanoparticles as plasmonic hot-spots under 450-640-nm light irradiation yields well-resolved resonance Raman spectrum of the oxidized form TMB+1. Using these hybrid nanofilms as visible light platforms for redox reaction of target analytes without additional oxidizing agents, the range of Raman-detectable compounds can be significantly expanded through a rapid ultrasensitive SERS screening of substances currently considered Raman-inactive.

Cost-Effective and Highly Efficient Manganese-Doped MoS2 Nanosheets as Visible-Light-Driven Photocatalysts for Wastewater Treatment

One of the main objectives in wastewater treatment and sustainable energy production is to find photocatalysts that are favorably efficient and cost-effective. Transition-metal dichalcogenides (TMDs) are promising photocatalytic materials; out of all, MoS₂ is extensively studied as a cocatalyst in the TMD library due to its exceptional photocatalytic activity for the degradation of organic dyes due to its distinctive morphology, adequate optical absorption, and rich active sites. However, sulfur ions on the active edges facilitate the catalytic activity of MoS₂. On the basal planes, sulfur ions are catalytically inactive. Injecting metal atoms into the MoS₂ lattice is a handy approach for triggering the surface of the basal planes and enriching catalytically active sites. Effective band gap engineering, sulfur edges, and improved optical absorption of Mn-doped MoS₂ nanostructures are promising for improving their charge separation and photostimulated dye degradation activity. The percentage of dye degradation of MB under visible-light irradiations was found to be 89.87 and 100% for pristine and 20% Mn-doped MoS₂ in 150 and 90 min, respectively. However, the degradation of MB dye was increased when the doping concentration in MoS₂ increased from 5 to 20%. The kinetic study showed that the first-order kinetic model described the photodegradation mechanism well. After four cycles, the 20% Mn-doped MoS₂ catalysts maintained comparable catalytic efficacy, indicating its excellent stability. The results demonstrated that the Mn-doped MoS₂ nanostructures exhibit exceptional visible-light-driven photocatalytic activity and could perform well as a catalyst for industrial wastewater treatment.