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Using heterogeneous photocatalysts for harvesting sunlight and converting it for water remediation and splitting are promising to mitigate the possible crisis of environment and energy. Among various composites, the MoS2‐based heterostructures and Ni‐based systems exhibit unique electronic, optical properties and redox capabilities, enabling their roles as photocatalysts. Herein, the impacts of chemical environments on the Ni electronic structures within the MoS2‐Ag‐Ni ternary systems are studied via X‐ray photoemission electron spectroscopy (X‐PEEM). Ni nanoparticles with two different sizes of 70 and 200 nm were loaded to MoS2 flakes with silver buffers as bridges. Heterostructures with a nominal mol percentage of (MoS2)77Ag3.7Ni19.3 were synthesized through an ultrasound‐assisted wet method. The oxidation states and various interfacial interactions of Ni with MoS2 in MoS2‐Ag‐Ni ternary composite are spectromicroscopically determined, combining the X‐ray absorption spectroscopy near Ni L‐edges and the imaging capability of the X‐PEEM. Results showed that Ni mainly retrains its chemical states of metal and native oxidizations without observable electronic features subjected to bonding with the sulfur from the MoS2 flakes. The charge migration channel set up by the Ag buffer thus contributes to electron–hole migrations that facilitate the photocatalytic performance of the ternary system eventually. [ABSTRACT FROM AUTHOR]

Raman spectroscopy/mapping is used to investigate the variation of Si phonon wavenumbers, i.e., lower wavenumber (LW ~ 495-510 cm−1) and higher wavenumber (HW ~ 515-519 cm−1) phonons, observed in Si-SiO2 multilayer nanocomposite (NCp) grown using pulsed laser deposition. Sensitivity of Raman spectroscopy as a local probe to surface/interface is effectively used to show that LW and HW phonons originate at surface (Si-SiO2 interface) and core of Si nanocrystals, respectively. The consistent picture of this understanding is developed using Raman spectroscopy monitored laser heating/annealing and cooling experiment at the site of the desired wavenumber, chosen with the help of Raman mapping. Raman spectra calculations for Si41 cluster with oxygen and hydrogen termination show strong mode at 512 cm−1 for oxygen terminated cluster corresponding to the vibration of surface Si atoms. This supports our attribution of LW phonons to be originating at the Si-SiO2 surface/interface. These results along with XPS show that nature of interface (oxygen bonding) in turn depends on the size of nanocrystals and LW phonons originate at the surface of smaller Si nanocrystals. The understanding developed can conclude the ongoing debate on large variation in Si phonon wavenumbers of Si-SiO2 NCps in the literature. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

2D materials have attracted tremendous research interest since the isolation of graphene. Their remarkable optical, electronic, and mechanical properties show that they hold great potential across a range of technological applications. As a result, there is a growing demand for low‐cost, low‐energy, and high‐resolution lithography methods that will enable the integration of 2D materials into complex integrated circuitry, biomedical devices, and in the generation of quantum‐confined nanostructures. Recent advances in scanning probe nanolithography (SPL) techniques for the lithography of 2D materials such as graphene, black phosphorus, molybdenum disulfide, and tungsten diselenide are discussed, including the various physiochemical aspects of subtractive and additive lithography of these materials. Examples of 2D‐material‐based devices fabricated by SPL and their properties are also described. The comparative advantages of the individual SPL techniques are discussed along with the future outlook of SPL for 2D materials. [ABSTRACT FROM AUTHOR]