Selecting effective eletrocatalyst from Cu single-atoms and nanoparticles for realizing highly sensitive electrochemical sensing of glucose and HO.

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 HO reduction and glucose oxidation were studied. Surprisingly, the electrocatalytic activity of Cu SAs and CuNPs showed significant differences in HO reduction and glucose oxidation. Compared with CuNPs, Cu SAs exhibit outstanding activity in the electrocatalytic reduction of HO 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 HO reduction. DFT results show that HO 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.