Hydrogen produced from water using photocatalysts driven by sunlight is a sustainable way to overcome the intermittency issues of solar power and provide a green alternative to fossil fuels. TiO2 has been used as a photocatalyst since the 1970s due to its low cost, earth abundance, and stability. There has been a wide range of research activities in order to enhance the use of TiO2 as a photocatalyst using dopants, modifying the surface, or depositing noble metals. However, the issues such as wide bandgap, high electron-hole recombination time, and a large overpotential for the hydrogen evolution reaction (HER) persist as a challenge. Here, we review state-of-the-art experimental and theoretical research on TiO2 based photocatalysts and identify challenges that have to be focused on to drive the field further. We conclude with a discussion of four challenges for TiO2 photocatalysts—non-standardized presentation of results, bandgap in the ultraviolet (UV) region, lack of collaboration between experimental and theoretical work, and lack of large/small scale production facilities. We also highlight the importance of combining computational modeling with experimental work to make further advances in this exciting field.

14 new MoS2 polymorphs were studied using first-principle calculations based on density functional theory. We found a new promising MoS2 candidate for photocatalytic and photovoltaic applications.

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The localized surface plasmon resonance (LSPR) effect in metal nanoparticles is important for many applications ranging from detectors and sensors to photovoltaic devices. The LSPR wavelength is sensitive to the shape, size, surface condition, and surrounding environment. Therefore, it is important to compare the optical properties of metal nanoparticles of nominally similar dimensions and external conditions, but fabricated with different techniques. Here, a systematic study of the optical properties of large, periodic arrays (3 Â 3 mm) of cylindrical, gold nanoparticles with diameters ranging from 39 6 4 nm to 167 6 5 nm and a height of 25 6 1 nm is presented. The large arrays allow us to investigate the optical properties using an integrating sphere setup collecting the light scattered and absorbed by the nanoparticles. To the best of our knowledge, such a setup has not been used previously for electron beam lithography (EBL) fabricated samples mainly due the large sample area required. The authors compare our results with relevant literature and find a good agreement, which confirms the expected reproducibility of EBL. Further, the authors compare our absorption and scattering measurements with previous absorption and scattering measurements on large arrays of gold nanoparticles prepared on glass using hole-mask colloidal lithography. Finally, a comparison with simulations using a finite difference time domain software package (Lumerical, Inc.) is presented. The simulation results matches well with experimental results and are also supporting and detailing our comparison with published literature. The authors find a good agreement between the two fabrication methods. The small deviations found can be contributed to differences in the particle size and density distributions. Published by the AVS. https://doi.

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