Single-molecule electrochemistry with enhanced fluorescence output
Electrochemical (EC) reactions are of crucial importance in diverse fields of nanoscience, ranging from electrocatalysis, fuel and solar cells to biological processes. We present electrochemical measurements with fluorescent output of the redox-sensitive dye, Methylene Blue (MB) at single-molecule level. Due to the low fluorescence quantum yield of MB (4%) we used fluorescence enhancement by individual gold nanorods (NRs) to achieve the required sensitivity. By measuring the same molecule at different EC potentials we show that the redox-induced fluorescence blinking dynamics can be used to determine the mid-point potential at the single-molecule level. From single-molecule data, we find a spread of mid-point potentials of about 50 mV.