Selecting effective eletrocatalyst from Cu single-atoms and nanoparticles for realizing highly sensitive electrochemical sensing of glucose and H ₂ O ₂

Which is more suitable as a sensing material between metal single-atoms and nanoparticles? Herein, electrocatalytic behaviors of copper single-atoms (Cu SAs) and copper nanoparticles (CuNPs) toward H₂O₂ reduction and glucose oxidation were studied. Surprisingly, the electrocatalytic activity of Cu SAs and CuNPs showed significant differences in H₂O₂ reduction and glucose oxidation. Compared with CuNPs, Cu SAs exhibit outstanding activity in the electrocatalytic reduction of H₂O₂ but exhibit weak activity in the electrocatalytic oxidation of glucose. On the contrary, CuNPs exhibit excellent activity in the electrochemical oxidation of glucose but have very weak electrocatalytic activity towards H₂O₂ reduction. DFT results show that H₂O₂ reduction is more favourable with Cu SAs; however, the electrochemical oxidation of glucose with CuNPs requires overcoming much lower energy barriers than that with Cu SAs. This study proves that both metal single-atoms and nanoparticles are not omnipotent, which provides ideas for constructing highly active sensing materials.