Porous two-dimensional (2D) materials have the potential to be used in many energy harvesting applications, particularly carbon capture and hydrogen (H
2) storage. This study is motivated by the successful synthesis of porous graphene with pyridinic nitrogen at the pore edges for carbon capture. To illustrate the potential of newly predicted CN, C
N, CN
![]()
Li, and C
N
![]()
Li monolayers for CO
capture and H
2 storage, we employ first-principles density functional theory (DFT) calculations. According to the stability tests, these CN, C
N, CN
![]()
Li, and C
N
![]()
Li monolayers are mechanically, energetically, dynamically, and thermally stable. Both Perdew–Burke–Ernzerhof (PBE) and Heyd–Scuseria–Ernzerhof (HSE06) band structure results indicate that these monolayers exhibit metallic property. Additionally, we explore the performance of CN monolayer for CO
molecule detection. The findings suggest that moderate physiosorption characterizes the interaction between CO
and the CN monolayer. The CN monolayer can potentially be used as a sensing material for CO
molecule because of its considerable change in the work function and fast recovery time. Also, the performance of CN
![]()
Li and C
N
![]()
Li monolayers has been explore for H
2 storage. It is revealed that single Li adsorption makes CN
![]()
Li and C
N
![]()
Li surfaces well-suited for considerable number of H
molecules uptake. Precisely, the CN
![]()
Li and C
N
![]()
Li structures can store up to 30H
molecules with an average E
values of -0.17 and -0.13 eV/H
, respectively. The H
molecule storage capacities of CN
![]()
Li@H
and C
N
![]()
Li@H
systems attain 7.50 wt% and 7.27 wt%, respectively at practical temperature and pressure. The estimated wt% values are higher than the 5.50 wt% target that needs to be reached by 2025. Our results demonstrate the potentials of CN monolayer and CN
![]()
Li/C
N
![]()
Li structures as promising candidates for CO
gas sensor and hydrogen storage applications.