Evolution of Atomistic Boron Clusters on Borophene Monolayers on Au(111)

Borophene is one of the quantum materials with remarkable metallicity, mobility, and high surface energy. Borophene exhibits polyphasy, and the vivid crystallographic structures determine its physical and chemical properties. Herein, using scanning tunneling microscopy (STM), we report the morphological evolution of liquid-phase exfoliated (LPE) borophene when adsorbed on Au(111). STM images show that monolayers of β12 borophene assemble on Au(111) for two cycles of spin-coating. For three cycles of spin-coating, the formation of atomistic clusters of boron is observed on the β12 borophene monolayers, hinting at strong interfacial interactions. The β12 monolayer thus acts as a template for the adsorption of clusters. Scanning tunneling spectroscopy data experimentally and density of states computationally confirm that these clusters are metallic in nature. Comprehensive calculations using density functional theory align well with the STM results and provide insight into the stability of boron clusters on β12 borophene upon adsorption on Au(111). Our work advances the understanding of LPE boron clusters and highlights the template morphology of β12 monolayers.