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Abstract Epitaxial growth of transition metal dichalcogenides (TMDs) by metalorganic chemical vapor deposition is a promising method for wafer-scale synthesis of monolayer films. This study focuses on a comparison of the epitaxial growth of MoS₂, WS₂, and WSe₂monolayers on 2 inch c-plane sapphire substrates using a cold-wall reactor with metal hexacarbonyl and hydride chalcogen sources. Uniform thermofluidic conditions enabled a comparative analysis of nucleation density, domain size, and lateral growth rate across TMD compounds, shedding light on the impact of TMD chemistry on epitaxial growth. Despite the use of chemically analogous precursors such as Mo(CO)₆or W(CO)₆and H₂S or H₂Se, significant differences in growth behavior are observed. Comprehensive structural, optical, and transport characterizations provide insights into sulfur versus selenium-based TMDs, advancing the understanding of optimized growth conditions for these emerging materials. 

Abstract C–H bond activation enables the facile synthesis of new chemicals. While C–H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C–H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C–C coupling mediated by 2D TMDCs to promote C–H activation and carbon dots synthesis. Our results shed light on 2D materials for C–H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials. 

C–H bond activation enables the facile synthesis of new chemicals. While C–H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C–H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C–C coupling mediated by 2D TMDCs to promote C–H activation and carbon dots synthesis. Our results shed light on 2D materials for C–H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials. 

C–H bond activation enables the facile synthesis of new chemicals. While C–H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C–H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C–C coupling mediated by 2D TMDCs to promote C–H activation and carbon dots synthesis. Our results shed light on 2D materials for C–H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials. 

Abstract Reproducible wafer-scale growth of two-dimensional (2D) materials using the Chemical Vapor Deposition (CVD) process with precise control over their properties is challenging due to a lack of understanding of the growth mechanisms spanning over several length scales and sensitivity of the synthesis to subtle changes in growth conditions. A multiscale computational framework coupling Computational Fluid Dynamics (CFD), Phase-Field (PF), and reactive Molecular Dynamics (MD) was developed – called the CPM model – and experimentally verified. Correlation between theoretical predictions and thorough experimental measurements for a Metal-Organic CVD (MOCVD)-grown WSe 2 model material revealed the full power of this computational approach. Large-area uniform 2D materials are synthesized via MOCVD, guided by computational analyses. The developed computational framework provides the foundation for guiding the synthesis of wafer-scale 2D materials with precise control over the coverage, morphology, and properties, a critical capability for fabricating electronic, optoelectronic, and quantum computing devices. 

The epitaxial growth of wafer-scale semiconducting TMDs monolayers (MoS 2 , WS 2 , WSe 2 ) on c-plane sapphire by metalorganic chemical vapor deposition (MOCVD) is demonstrated and the resulting structural and optical properties of the films are compared to elucidate trends based on metal and chalcogen species. The sulfur based TMDs exhibit improved epitaxy, fewer defects and increased photoluminescence intensity on sapphire compared to WSe 2 which is attributed to a smaller effective lattice mismatch and improved stability. 

Movies showing the nucleation of WSe2 on Al2O2 with mixed (Se/O) and single (Se) steps.