If Nocera's method is not truly 100% efficient, i.e. the
recombination energy equals the electrical energy of the
electrolysis, then methods I have suggested for overcoming
electrolyte resistance due to bubble formation, large gap size, the
requirement for electrode separation membranes, the requirement for
use of DC electrolysis current, and the requirement to overcome large
interface potential drops, might be of use in combination with
Nocera's catalysts. See:
http://mtaonline.net/~hheffner/Electrolyser.pdf
http://www.mtaonline.net/~hheffner/ElectrolyseAC.pdf
and possibly p. 16 of:
http://www.mtaonline.net/~hheffner/DryPile.pdf
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/