Figure 3. Dependence of catalytic activity on the surface Cu ⁺ species of PdCu _x –Cu ₂ O nanocomposites evolved from fresh Pd-Cu alloy.

(a) X-ray diffraction patterns of the used Pd-Cu alloy catalysts. (b) The relationship between surface Cu⁺ content and benzyl alcohol conversion. (c) HRTEM image of the fresh PdCu₇ catalyst. (d) HRTEM image of the used PdCu₇ catalyst exhibiting the phase segregation of PdCu_x and Cu₂O. Scale bar, 2 nm.