Tuning the Ratio of Pt(0)/Pt(II) in Well-Defined Pt Clusters Enables Enhanced Electrocatalytic Reduction/Oxidation of Hydrogen Peroxide for Sensitive Biosensing.

Rational design and construction of advanced sensing platforms for sensitive detection of H2O2 released from living cells is one of the challenges in the field of physiology and pathology. Noble metal clusters are a kind of nanomaterials with well-defined chemical composition and special atomic structures, which have been widely explored in catalysis, biosensing, and therapy. Compared with noble metal nanoparticles, noble metal clusters exhibit great potential in electrochemical biosensing due to their high atom utilization efficiency and abundant reactive active sites. Herein, Pt nanoclusters anchored on hollow carbon spheres (PtNCS/HCS) were successfully prepared for sensitive detection of H2O2. By tuning the ratio of Pt(0)/Pt(II) at different annealing temperatures, the optimized PtNCS/HCS-550 showed higher H2O2 reduction and oxidation catalytic activities than other control samples. Density functional theory calculations revealed that H2O2*can be better activated and dissociated in the Pt0II model featured with the co-existence of Pt(0)/Pt(II) and the key intermediates OOH*/OH* have a stronger interaction with the Pt0II model. As a concept application, the electrochemical biosensing platform was successfully applied to sensitive detection of H2O2 released from the cells.