General Model of Electrochemical Hydrogen Absorption into Metals

A general model for the hydrogen adsorption and hydrogen absorption into metals has been proposed. It includes reactions of hydrogen evolution M+H{sub 2}O+e=MH{sub ads}+OH{sup {minus}}; MH{sub ads}+H{sub 2}O+e=M+H{sub 2}+OH{sup {minus}}; and 2MH{sub ads}+2M+H{sub 2}; hydrogen absorption MH{sub ads}+MH{sub abs}; and hydrogen diffusion into metal. This problem leads to a system of differential equations which was solved using the differential algebraic equations method. Solutions were obtained for constant potential and constant current charging/discharging in the case of semi-infinite and finite length diffusion for planar, spherical, and cylindrical diffusion. Numerical solutions give new information about the reaction mechanism and may be useful in the determination of the kinetics of these processes.