The emission of mercury from anthropogenic activities is a serious concern in both developed and developing countries due to its high toxicity and persistence. Here, carbon nitride nanosheets (CNNS) were attained via a two-step thermal etching method and applied for Hg° removal. Proper deposition of ZnS can markedly reinforce the Hg° capture ability of CNNS. 10ZnS/CNNS notably outperforms ZnS and CNNS at 100℃, which is primarily attributed to surface chemisorbed oxygen species and polysulfide active sites. Besides, Hg° adsorption and thermal catalytic oxidation pathways are further disclosed using quantum chemistry calculations based on density functional theory (DFT). The calculation results show that the presence of zinc species is beneficial to the decomposition of adsorbed oxygen, which plays a key role in the catalytic oxidation of Hg0, thereby contributing to the enhancement of mercury removal performance.