Selecting effective sensing material from metal single-atoms and nanoparticles for boosting electrochemical sensing

Which is more suitable as the sensing material for metal single-atoms and nanoparticles? Here, the 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 for H2O2 and glucose. Compared with CuNPs, Cu SAs exhibit outstanding activity in electrocatalytic reduction of H2O2, but are inert 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 for H2O2 reduction. DFT results show that H2O2 reduction is more favourable on Cu SAs, but the electrochemical oxidation of glucose on CuNPs requires overcoming much lower energy barriers than on Cu SAs. This study proves that both metal single-atoms and nanoparticles are not omnipotent, which provides ideas for constructing highly active sensing materials.