Using density functional theory within the generalized gradient approximation (GGA), we explore the
elastic and electronic properties of monolayer boronitrene containing a double line of substituted carbon
atoms. This C-functionalized boronitrene structure, referred to as BN/C zigzag-short, has a significantly
reduced band gap of about 1.79 eV due to the presence of carbon in the lattice but shows no significant
change in its elastic properties compared to pristine boronitrene. The effect of strain on the band offset is
explored for various applied strains. It is shown that the band offset changes significantly as a function of
biaxial and uniaxial strain, opening an avenue for band offset engineering.