Hydrogen has been inserted by chemical methods into a synthetic c-manganese dioxide characterized by 41% de Wol disorder and a low amount of microtwinning. 23 Compounds covering the insertion range 0.00∏s∏0.82 where s is the value in MnO 1.966 H s were prepared. Both XRD and FTIR evidence indicated homogeneous insertion in the range 0.00∏s∏0.34 followed by heterogeneous reaction in the range 0.34∏s∏0.82. Starting from the position that the structure of the predominant ramsdellite type lattice may be characterized by the distance z between the apical oxygens normal to the c axis of the manganese occupied octahedra and the angle b that the apical vector makes with the b axis a map was developed enabling the structure of the inserted compounds to be followed. In the homogeneous range, where H+ and e are mobile, insertion led to expansion of z with little change in b whereas in the heterogeneous range, where H+ is relatively immobile in the final product, a large change in b was observed which is believed to result from the location of H+ in the final product. Chemical insertion of hydrogen into EMD (electrodepositedn in MnO n 1.966 8 % microtwinning 17 8 in XRD patterns which occur with H-insertion yield in principle % de Wol disorder 41 8 more information with low microtwinned materials and this BET surface area/m2 g−1 22a 9 information may in turn advance understanding of the highly microtwinned counterparts. A feature of this examination was aObtained from Fig. 8 in ref. 9 which displays the relationship between the large number of samples at diÂering insertion levels com-BET surface area and geometrical current density of deposition for SBP-EMD, which for material SBPA=1.2 A dm−2.pared to previous work.

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