Ascertaining the function of in-plane intrinsic defects and edge atoms is necessary for developing efficient low-dimensional photocatalysts. We report the wireless photocatalytic CO2 reduction to CH4 over reconstructed edge atoms of monolayer 2H-WSe2 artificial leaves. Our first-principles calculations demonstrate that reconstructed and imperfect edge configurations enable CO2 binding to form linear and bent molecules. Experimental results show that the solar-to-fuel quantum efficiency is a reciprocal function of the flake size. It also indicates that the consumed electron rate per edge atom is two orders of magnitude larger than the in-plane intrinsic defects. Further, nanoscale redox mapping at the monolayer WSe2–liquid interface confirms that the edge is the most preferred region for charge transfer. Our results pave the way for designing a new class of monolayer transition metal dichalcogenides with reconstructed edges as a non-precious co-catalyst for wired or wireless hydrogen evolution or CO2 reduction reactions.

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The aim of this research is to find out the effect of GaAlAs diode laser 808 nm exposure on MCF-7 breast cancer cells in vitro with and without the addition of a photosensitizer. Methylene blue (C16H18N3SCl) with concentration of 2 µM is used as the photosensitizer based on the preliminary results of cytotoxicity assay. Energy dose is set in the range of 23, 043 to 322, 062 J/cm2. Laser exposure with the addition of the photosensitizer generates the highest percentage of cell death of 20.80% at energy dose of 184, 344 J/cm2 and cell death begin to decrease at energy dose above this value. This behavior is likely caused by photodegradation and photobleaching effect of the photosensitizer due to the longer exposure time. However, the percentage of cell death without the addition of photosensitizer is increased proportionally to the increase of energy dose and achieved 32, 45% cell mortality at 299, 559 J/cm2. This study not only shows that the exposure of infrared laser can be used to inactivate cancer cells but also determines its optimum energy dose, makes it a possible candidate for photodynamic therapy in the future.