Electroplating and electropolish typically employ large volumes of hazardous and toxic materials. Ionic liquids provide a “green” and environmentally-friendly alternative to both processes, generally improve a number of process parameters, and can permit processes that are difficult or impossible in aqueous approaches.

When ionic liquids replace aqueous chemistries for electroplating, energy efficiency of the plating process typically increases from 20% to 90%; hydrogen gas production is significantly reduced. The non-volatile nature of ionic liquids reduces the need for air pollution controls. Electroplating Chromium using ionic liquids is especially advantageous in that hexavalent Chromium, which is highly toxic and carcinogenic, can be replaced by the trivalent form, which is much less toxic. While most metals that can be electroplated from aqueous solution can also be electroplated from ionic liquids, two examples are presented where the reverse is not true. The results are presented of electroplating Aluminum and Molybdenum using an ionic liquid composed of Urea and Choline Chloride.

Electropolishing is a complimentary process to electroplating in that microprojections (peaks) on a metal surface are preferentially electrochemically etched, while microdepressions (valleys) are minimally etched. This produces a surface that is mirror-like and smooth on an atomic scale. Ionic liquids composed of choline chloride and propylene glycol have been used to replace the toxic and hazardous electropolish baths using concentrated sulfuric and phosphoric acids. Greater electrical current efficiency, reduced Hydrogen production, reduced generation of acid mists, and room temperature operation are additional benefits. Results of ionic liquid electropolishing of Stainless Steel are presented.