Single-atom catalysts (SACs) have attracted great interest in heterogeneous catalysis because of their excellent catalytic performance and suitable stability. Here, we construct a series of SACs by locating transition metal (TM) atoms on Cu2O(111) using first-principles. Due to the mightily change of the electronic and geometric properties, TM1/Cu2O(111) not only has good stability (binding energy less than − 2 eV), but also the catalyst, like alloys, retains the metallicity of single atoms to the greatest extent. Furthermore, the SACs TM1/Cu2O(111) reduce the band gap and promote charge transfer and charge separation. Pd1/Cu2O(111) exhibits excellent dual-effect catalytic capacity (overpotential of 1.23 V), with oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) barriers of 0.353 eV and 0.662 eV respectively. In the N2 reduction reaction (NRR), Mo1/Cu2O(111) performs the best. The distal mechanism is the most suitable reaction path in the catalytic reaction, and the free energy barrier of the rate-determining step is 0.464 eV. Our results provide a reference for the anchoring of TM in Cu2O(111), which facilitates the precise design of novel SACs.