A novel and nonstoichiometric Mn1–xMo(S,O)4–y oxysulfide catalyst with oxygen vacancies and a partial Mo6+-to-Mo4+ transition after the substitution of sulfur was synthesized for an efficient photocatalytic hydrogen evolution reaction (PHER). With appropriate sulfur substitution, a MnMoO4 semiconductor with a wide band gap was converted to Mn1–xMo(S,O)4–y with a narrow gap and a suitable band position for PHER. MnMo oxysulfide of 50 mg achieved a high PHER rate of 415.8 μmol/h under visible light, an apparent quantum efficiency (AQE) of 4.31% at 420 nm, and a solar-to-hydrogen (STH) conversion efficiency of 1.28%. Oxygen vacancies (VO) surrounded by low coordination metal atoms act as active reaction sites, which strengthen water adsorption and activation. Here, we demonstrate that sulfur substitution of MnMoO4 for lowering its wide band gap can not only disturb the strict periodicity of the lattice but also the valence states of Mn and Mo for enhancing PHER via material design.
Fuhao An,Yue Zhao,Haining Li,Jiao Meng,Lanya Jiao,Zongyi Zhang,Xu Li,Xuan Sun
Development of organic molecules with high photothermal conversion efficiency (PCE) in the near-infrared (NIR) window is a vital yet challenging topic in the field of photothermal therapy. A series of thionated perylenediimides (PDI-4CHA-S) derivatives have been synthesized by replacing carboxylic oxygens in imides with sulfur atoms, providing chances to unravel the effect of thionation on the photophysical properties toward photothermal agents (PTAs) with high PCE. In the presence of the electron-donating substituents at the bay-position, sulfur atoms participate the intramolecular charge transfer (ICT), which induces remarkable redshift in the absorption maximum. Meanwhile, the ICT together with the heavy atoms effect of sulfur atoms promotes the intersystem crossing (ISC), resulting in the generation of the active oxygen species (ROS) upon photoexcitation. Interestingly, the quantum yield of ROS decrease with increasing the number of S-substitutes, which is the resultant of the attenuated ICT in the case of multiple S-substitution. Overall, the promotion in ISC due to thionation is negligible compared to the quenching of the radiation transition and enhancement of the absorption coefficient caused by ICT, hence the energy of the excited PDI-4CHA-S molecules is depleted mainly in the form of heat, leading to the ultrahigh PCE of 88.0% under 808 nm laser irradiation . In particular, the trithionated PDI-4CHA-3S performs surprisingly high PCE in the second near-infrared (NIR-II) window (1064 nm). The superior photothermal effect and excellent photostability of the thionated PDI derivative provide them promising photothermal agents for NIR photothermal therapy.
Diabetic liver dysfunction is characterized by oxidative stress and disrupted cysteine (Cys) metabolism, but noninvasive monitoring tools remain lacking. Here, we developed a sulfur-substituted hemicyanine-based nanosensor (S-Nanoprobe) that generates enhanced near-infrared photoacoustic signals upon selective Cys recognition. The sulfur substitution improved vibrational relaxation efficiency, yielding a stronger photoacoustic signal than oxygen-substituted analogs, with a 0.12 μM detection limit and exceptional selectivity (no interference from homocysteine or glutathione). In streptozotocin-induced diabetic mice, the probe enabled noninvasive tracking of hepatic Cys dynamics, revealing significant Cys accumulation in diabetic mice (higher than controls), while metformin-treated mice showed intermediate levels. Histopathological analysis confirmed correlations between Cys levels and liver injury severity. This technology provides a novel molecular imaging approach for early assessment of diabetic liver dysfunction and establishes a versatile platform for studying thiol metabolism. The probe’s high specificity, biocompatibility, and signal-to-noise ratio make it promising for translational applications in metabolic disease monitoring.
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