Chemical imaging of surface reactions by multiplexed capillary electrophoresis.

A new technique for in situ imaging of surface reactions and screening heterogeneous catalysts by using multiplexed capillary electrophoresis was developed. By bundling together the inlets of a large number of capillaries, an aligned imaging probe can be created that can be used to sample directly products formed at a surface with spatial resolution determined by the outer diameter of the capillaries. In this work, we used surfaces made of platinum, iron, or gold wires to generate electrochemical products for imaging. Various shapes were recorded including crosses, squares, and triangles. A model multifunctional catalytic surface consisting of both iron and platinum electrodes in the shape of a cross was also imaged successfully. Each of the two wires produced a different electrochemical product that could be subjected to capillary electrophoresis to provide chemical selectivity. On the basis of the collected data, we were able to distinguish the products from each wire in the reconstructed image.