Fluidic channel coated with metal catalysts and devices and methods relating thereto

A hand-held millifluidic device comprising:

• two or more reagent reservoirs, and
• a removable chip having
• two or more millifluidic supply channels, each of the two or more millifluidic supply channels being capable of fluidly communicating with one of the two or more reservoirs,
• a primary channel in fluid communication with the two or more millifluidic supply channels, the primary channel having a width of about 0.15 millimeters to about 10 millimeters and a strip of catalytic structures along at least a portion of the primary channel having a width less than the width of the primary channel, wherein the strip of catalytic structures is formed by flowing a reagent solution and a reducing agent solution through the supply channels into the primary channel at laminar flow conditions such that a distinct reagent stream and a distinct reducing agent stream are achieved within the primary channel forming a stream interface whereat catalytic structures are formed on the primary channel having controlled dimensions and morphology.