Hydrogen water electrolysis

Multistep Thermochemical Water Splitting. Multistep thermochemical hydrogen production methods are designed to avoid the problems of one-step water spHtting, ie, the high temperatures needed to achieve appreciable AG reduction, and the low efficiencies of water electrolysis. Although water electrolysis itself is quite efficient, the production of electricity is inefficient (30—40%). This results in an overall efficiency of 24—35% for water electrolysis. 

A detailed discussion of thermochemical water splitting is available (155,165—167). Whereas many problems remain to be solved before commercia1i2ation is considered, this method has the potential of beiag a more efficient, and hence more cost-effective way to produce hydrogen than is water electrolysis. 

Hydrogen peroxide can be dissociated over a catalyst to produce oxygen, water, and heat. It is an energetic reaction, and contaminants can spontaneously decompose the hydrogen peroxide. Oxygen from water electrolysis is used for life support on submarines. 

Where low-cost electricity is available, water electrolysis is used to produce hydrogen. In water electrolysis... 

Wurster, R. Water Electrolysis and Solar Hydrogen Demonstration Projects 27... 

A process involving water electrolysis is the production of heavy water. During cathodic polarization the relative rates of deuterium discharge and evolution are lower than those of the normal hydrogen isotope. Hence, during electrolysis the solution is enriched in heavy water. When the process is performed repeatedly, water with a D2O content of up to 99.7% can be produced. Electrochemical methods are also used widely in the manufacture of a variety of other inorganic and organic substances. 

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Chonglun F., Piron D.L., Paradis R, Hydrogen evolution on electrodeposited nickel-cobalt-molybdenum in alkaline water electrolysis, Electrochim. Acta, 39(18), 2715-2722,1994. 

Dos Santos A.M.H., Acioli M.L., Da Silva J.G. Jr., Pereira S.J.C., Vilar E.O., Tonholo J., Preliminary investigation of some commercial alloys for hydrogen evolution in alkaline water electrolysis, Int. ]. Hydrogen Energ., 29, 235-241, 2004. 

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