Investigation on standard entropy change of metal hydrides and work function of metals

We focused on the work function of metals as an index of ion binding property between metals and hydrogen and analyzed the relation between the standard entropy change of metal hydrides and the work function of metals (alloys). The standard entropy change of saline hydrides and metallic hydrides roughly increased with the work function. It was indicated that hydrogen storage alloys consist of metal elements A and B whose work functions are small and large, respectively. The standard entropy changes of alloy-based metal hydrides with different composition ratio Delta S-0 linearly increased with the work functions of the alloys W-c. W-c also linearly increased with the bulk modulus B-c. Then, it was found that Delta S-0 was proportional to the standard heat of formation Delta H-0 because dW(c)/dB(c), d Delta S-0/dW(c) and d Delta H-0/dB(c) are constant. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study focused on the work function of metals as an index of ion binding property between metals and hydrogen, and analyzed the relationship between the standard entropy change of metal hydrides and the work function of metals (alloys). It was found that the standard entropy changes of alloy-based metal hydrides linearly increased with the work functions of the alloys, which also increased with the bulk modulus. Additionally, the standard entropy change was proportional to the standard heat of formation due to certain constant relationships between parameters.