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We report on the effects of substrate, starting material, and temperature on the growth of MoS(2) atomic layers by thermal vapor sulfurization in a tube-furnace system. With Mo as the starting material, atomic layers of MoS(2) flakes are obtained on sapphire substrates while a bell-shaped MoS(2) layer, sandwiched by amorphous SiO(2), is obtained on native-SiO(2)/Si substrates under the same sulfurization conditions. An anomalous thickness-dependent Raman shift (A(1g)) of the MoS(2) atomic layers is observed in Mo-sulfurizations on sapphire substrates, which can be attributed to the competition between the effects of thickness and the surface/interface. Both effects vary with the sulfurizing temperatures for a certain initial Mo thickness. The anomalous frequency trend of A(1g) is missing when using MoO(3) instead of Mo as the starting material. In this case, the lateral growth of MoS(2) on sapphire is also largely improved. Furthermore, the area density of the resultant MoS(2) atomic layers is significantly increased by increasing the deposition temperature of the starting MoO(3) to 700 °C; the adjacent ultrathin MoS(2) grains coalesce in one or other direction, forming connected chains in wafer scale. The thickness of the so-obtained MoS(2) is generally controlled by the thickness of the starting material; however, the structural and morphological properties of MoS(2) grains, towards large area and continuous atomic layers, are strongly dependent on the temperature of the initial material deposition, and on the temperature of sulfurization, because of the competition between surface mobility and atom evaporation.

This paper demonstrates an optimized fabrication of amorphous Ru nanoparticles through annealing at various temperatures ranging from 150 to 700 °C, which are used as water oxidation catalyst for effective electrochemical water splitting under a low overpotential of less than 300 mV. The amorphous Ru nanoparticles with short-range ordered structure exhibit an optimal and stable electrocatalytic activity after annealing at 250 °C. Interestingly, a small quantity of such Ru nanoparticles in a thin film on fluorine-doped tin oxide glass is also effectively driven by a conventional crystalline silicon solar cell that has excellent capability for harvesting visible light. Remarkably, it achieves an overall solar-to-hydrogen efficiency of 11.3% in acidic electrolyte.

Photovoltaics and photocatalysis are two significant applications of clean and sustainable solar energy, albeit constrained by their inability to harvest the infrared spectrum of solar radiation. Lanthanide-doped materials are particularly promising in this regard, with tunable absorption in the infrared region and the ability to convert the long-wavelength excitation into shorter-wavelength light output through an upconversion process. In this review, we highlight the emerging applications of lanthanide-doped upconversion materials in the areas of photovoltaics and photocatalysis. We attempt to elucidate the fundamental physical principles that govern the energy conversion by the upconversion materials. In addition, we intend to draw attention to recent technologies in upconversion nanomaterials integrated with photovoltaic and photocatalytic devices. This review also provides a useful guide to materials synthesis and optoelectronic device fabrication based on lanthanide-doped upconversion materials.

In this study, B-doping of vapour–liquid–solid (VLS) grown Si nanowires was studied. First, the different effects of B2H6 gas on nanowire structures during VLS growth of both Au-catalysed and Al-catalysed Si nanowires were investigated. While Au-catalysed Si nanowires grown with B2H6 gas reveal significant morphological changes, resulting in cone-shaped nanowires, structures comparable to un-doped nanowires were observed from Al-catalysed Si nanowires, which may be explained by thermodynamic properties of Au and Al catalyst in the presence of boron. In addition, successful incorporation of boron and controllability of its concentration in Si nanowires, maintaining the structural quality of the nanowires, was achieved by a post-synthesis in situ plasma B2H6 doping process.