Electrocatalytic CO
2
reduction has attracted much attention due to its potential to facilitate an artificial carbon cycle under mild conditions. In this paper, we investigate the catalytic performance of MoTe
2
and MoTe
2
-InN heterojunction-loaded single-atom catalysts (SACs) for CO
2
reduction using density-functional theory (DFT) calculations. Among the catalysts studied, Ni@MoTe
2
(-0.04 V) and Ni-MoTe
2
-InN (-0.16 V) exhibited lower limiting potentials. This improvement is attributed to the reduced energy required to activate the Ni-O
2
bond in the *OCHO + H⁺ + e⁻ → *HCOOH step. Remarkably, we observed a strong linear correlation between the adsorption energy of *OCHO and the catalytic activity for the generation of the two-electron product, HCOOH. This correlation challenges the conventional volcano-shaped relationship and serves as a reliable descriptor for predicting the limiting voltage. Furthermore, we applied this descriptor to the TM@MoTe
2
-InN system, confirming its applicability. This finding further validates that the adsorption energy of the intermediate *OCHO is an effective descriptor, significantly reducing the computational resources required for identifying high-performance catalysts. This study provides an avenue for the theoretical design of efficient electrocatalysts for CO
2
RR.