Hexagonal boron nitride on metal surfaces as a support and template

The synthesis and characterization of two dimensional materials are in the focus of nanomaterial and surface science, heterogeneous catalytic and nanoelectronic research laying the basis for various technological applications. Hexagonal boron nitride (h-BN) is an important member of 3D and reduced dimensional materials. Atomically clean sp2-hybridized 2D nano-layers can be grown on various metal supports by different chemical and physical vapor deposition techniques. In case of a significant lattice mismatch and a strong interaction at the h-BN/metal interface, a periodically undulating monolayer - a so-called "moire` structure" - is formed. In the present review, we address some important characteristics of h-BN prepared on several metal surfaces, and we focus on its application as a template for individual atoms, metal clusters and molecules. Moreover, several experimental findings are collected about the features and applications of monolayer h-BN nanosheets as supporting materials. We highlight the results of recent surface science studies, which emphasize the unique role of h-BN including nanomeshes in characteristic adsorption properties, stability and catalytic activity. The characterization of few layer and defective h-BN involving their catalytic applications are also the subject of the present review. We present a comprehensive overview on the electronic and vibrational states of nanoparticles (covered by adsorbates, as well) monitored by surface spectroscopy tools, e.g. XPS, ARPES, UPS, LEIS, AES, STS and HREELS. We also elaborate on the structural and morphological information of h-BN nanoobjects obtained by scanning probe microscopy (SPM). It is also highlighted that density functional theory (DFT) is considered as a very important complementary technique contributing to the better understanding of experimental results. Beside updated recollection of key findings, we outline the present and future research directions of 2D materials and their heterostructures including h-BN-based systems.