I have referenced five inorganic chemistry textbooks.Here are them:
[1]Zhao Fengyi, Guo Dewei, Gui Mingde.Inorganic Chemistry Series Volume 5[M].Beijing:Science Press,1990:92-93.
[2]Zhang Zude.Inorganic Chemistry[M].Hefei:China University of Science and Technology Press,2018.
[3]Song Tianyou, Xu Jianing.Inorganic Chemistry Volume II[M].Beijing:Higher Education Press,2015.
[4]N.N.Greenwood, A.Earnshaw.Elemental Chemistry(Middle Volume)[M].Beijing:Higher Education Press,1996.
[5]Yan Xuanshen, Wang Changfu.General Inorganic Chemistry[M].Beijing:Peking University Press,2016.
I checked the part of Oxygen and Sulfur,including persulfate and hydrogen peroxide.I found different book giving different reactions,but the method I gave, that is, the method of hydrolysis of (NH4)2S2O8, is the majority.
(In fact,the literature [4] denied this method,[1] gave the Ammonium salt-Potassium salt combination method,and [3] only gave the method of K2S2O8.)
There are also some papers:
[1]Zhao Ke, Li Shuxian. Production method and application of hydrogen peroxide[J]. Chlor-Alkali Industry, 2000, 11: 22-23.
[2]Berglin.Method in the production of hydrogen peroxide[P].US4552748,1985.
In summary,although there is no such method on Wikipedia,the electrolysis method is truly exist and had been used.
(I think this may happen because of the difference in the region.For example,in sulfuric acid industry,the preparation of SO2, sulfur is used in European countries, but pyrite (FeS2) is used in China.That makes difference in books and documents.
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