Research Article

Enhanced Solar Photoelectrochemical Conversion Efficiency of ZnO:Cu Electrodes for Water-Splitting Application

Figure 4

FESEM images showing the surface morphology of the doped ZnO films with different Cu doping concentrations. (a) 0.1 μM Cu2+, (b) 0.3 μM Cu2+, (c) 1.3 μM Cu2+, and (d) 26.4 μM Cu2+ concentrations.
928321.fig.004a
(a)
928321.fig.004b
(b)
928321.fig.004c
(c)
928321.fig.004d
(d)