Green Process for Preparation of Nickel Hydroxide Films and Membranes
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JMEPEG https://doi.org/10.1007/s11665-020-05100-5
Green Process for Preparation of Nickel Hydroxide Films and Membranes Audrey Vecoven, Dewan Russel Rahman, and Allen W. Apblett (Submitted March 5, 2020; in revised form July 21, 2020; Accepted: 21 August 2020) Nickel hydroxides have numerous applications including as battery electrodes, electrochromic devices, electrochemical sensors, and supercapacitors and in such processes as photocatalysis, electrocatalysis, and electrosynthesis. A simple solution growth process for production of beta-Ni(OH)2 has been developed. The process involves dissolution of nickel hydroxide powders in concentrated ammonia to form [Ni(NH3)6](OH)2. If ammonia is allowed to evaporate from the resulting solution, the dissolution process is reversed and crystalline films of beta-Ni(OH)2 are deposited that consist of closely packed micron-sized clumps of thin plates. Addition of sodium aluminate to the solution makes it possible to also prepare alpha nickel hydroxide as free standing membranes at air–water interface. The overall procedure can be described as a green process since it eliminates the environmental burden of by-product production because Ni(OH)2 is simply dissolved and transformed into the desired material without producing waste salts such as ammonium nitrate or ammonium chloride that would be produced by a conventional precipitation approach for Ni(OH)2 membrane or film preparation. Keywords
chemical bath deposition, electronic materials, green industry, nickel hydroxide
1. Introduction Nickel hydroxides are best known for their applications as electrode materials in batteries due to the popularity of NiCad batteries (nickel–cadmium), nickel metal hydride batteries (NiMH), and their use in rarer battery types such as nickel hydrogen (NiH2) batteries that have played an important part of the space program, and nickel iron (NiFe) batteries that are excellent rechargeable batteries with a low environmental impact (Ref 1-4). Nickel hydroxide has a high lithium storage capacity leading to applications as anode materials for lithiumion batteries (Ref 5, 6). However, nickel hydroxides have beneficial electrochemical and photochemical properties that have led to significant technological applications beyond their use in batteries (Ref 7). They are useful co-catalysts for photocatalytic hydrogen production from water (Ref 8, 9), electrocatalysts for the oxygen evolution reaction (Ref 10, 11) and for small molecule electrocatalysis in fuel cells, energy storage, organic synthesis, and wastewater treatment (Ref 12). Their electrochemical behavior has led to applications as sensors for a wide array of analytes including vitamins, [Additional Information] This article is an invited paper selected from presentations at the ‘‘11th International Symposium on Green and Sustainable Technologies for Materials Manufacturing and Processing,’’ held during Materials Science & Technology (MS&T19), September 29–October 3, 2019, in Portland, OR, and has been expanded from the original presentation. Audre
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