The chemisorption energy of hydrogen on ZnO/Ni composite substrate is investigated using the Green function method and the complex-energy-plane integration approach. The tight-binding approximation is employed to model the semiconductor ZnO by a finite chain of alternating s- and p-orbitals, while the semi-infinite metal Ni is represented by a linear chain of d-orbitals. The impurity effect on the chemisorption energy is evaluated. The calculation shows that: (1) the chemisorption energy is a monotonously decreasing function of the ZnO thickness; (2) the presence of impurities Cu and Pt (Co and W) can weaken (strengthen) the chemisorption process and (3) the impurity effects are most significant when the impurity is closest to the nickel surface.
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