Highly dispersive Pt-Pd nanoparticles on graphene oxide sheathed carbon fiber microelectrodes for electrochemical detection of H2O2 released from living cells

We report a facile strategy for the synthesis of surfactant-free, small and highly dispersive Pt-Pd nanoparticles on graphene oxide (Pt-Pd NPs/GO) by an electroless deposition method, which is sheathed on carbon fiber microelectrodes (CFMs) as an electrochemical sensing platform for highly sensitive and selective detection of hydrogen peroxide (H2O2) released from the living cells. GO serves as the reducing agent and stabilizer for electroless deposition of Pd NPs on the surface of GO owing to its low work function (4.38 eV) and highly conjugated electronic structure. The obtained Pd NPs/GO have a relatively high work function (4.64 eV), and thereby could be used as stabilizer for synthesis of surfactant-free, small and highly dispersive Pt-Pd NPs/GO by chemical reduction of K2PtCl4. The obtained Pt-Pd NPs have a uniform size of 4.0 +/- 0.6 nm on the surface of GO. Moreover, the Pt-Pd NPs/GO sheathed CFMs exhibit an excellent electrocatalytic activity for the reduction of H2O2 with a low detection limit of 0.3 muM and good selectivity. These good properties enable the modified microelectrode to detect the H2O2 released from living cells.