Context <p>The development of novel nano-ceramic composite materials significantly enhances the design quality and performance of ceramic jewelry. This research utilizes density functional theory to create innovative nano-ceramic materials, specifically Janus SiC/MoTeS and SiC/MoSTe, and examines their structural and electronic characteristics. The study explores the influence of biaxial and vertical strain on the modulation of the band gap in Janus heterojunctions. Findings reveal that both of Janus heterojunctions exhibit notable structural stability. The SiC/MoTeS and SiC/MoSTe configurations are identified as indirect band gap semiconductors, with band gaps measuring 0.658 eV and 0.447 eV, respectively. Electron transfer within the heterojunction occurs from SiC to MoTeS, which contributes to enhanced structural stability. Furthermore, strain is shown to effectively modulate both the band gap values and optical absorption properties of the Janus heterojunctions. The superior properties of these Janus ceramic heterojunctions suggest their promising applications in ceramic products.</p> Methods <p>The CASTEP software package is used for related calculations. The generalized gradient approximation with the Perdew-Burke-Ernzerhof functional was employed to describe the exchange–correlation functional and the electron–ion interactions. A more accurate hybrid functional, HSE06, was also used to correct the band gap results, as the PBE functional tends to underestimate the width of the band gap. The DFT-D3 scheme was used to describe the van der Waals interactions between layers.</p>