The possibility of creating composite proton electrolytes with the addition of nanodiamond (ND) to caesium pentahydrodiphosphate has been studied. Changes in the structural properties of salt in the composite, morphology, and proton conductivity depending on the composition for (1 – x)CsH(PO) – xND (x – mole fraction) in a wide range of compositions (x = 0 – 0.99) are considered. It is shown that there is no chemical interaction between the components and the structure of CsH(PO) (P2/c) with an increase in the proportion of ND is preserved during the dispersion and partial amorphization of the salt. Using IR spectroscopy, information was obtained on the mechanism of formation of composite electrolytes due to partial binding of salt protons to surface OH NDs hydroxo groups. This leads to the formation of a weaker network of hydrogen bonds in CsH(PO). A uniform distribution of salt particles in composites and a decrease in particle size as a result of the interfacial surface interaction of the components are shown. Melting enthalpy of CsH(PO) decreases disproportionately to the salt content with an increase in the proportion of ND due to an increase in the proportion of the amorphous phase in the composites. There is a significant increase in the proton conductivity of CsH(PO) in composites to two orders of magnitude with a maximum at x = 0.9 and a decrease at x 0.95 due to the percolation effect of the conductor-insulator type. The activation energy of the conductivity of composites decreases slightly. The studied composites have a relatively high proton conductivity at medium temperatures and chemical stability, which creates prospects for their use as proton membranes of electrochemical devices.
Demakova et al. (Wed,) studied this question.