Optimization of photoelectrochemical performance in Pt-modified p-Cu₂O/n-Cu₂O nanocomposite

As it is expected to be one of the most promising materials for utilizing solar energy, Cu₂O has attracted considerable attention with respect to the achievement of solar energy conversion. Until now, the photocurrent densities of all planar structure of the Cu₂O photocathode have not even come close to the theoretical value of -14.7 mA cm^-2 due to the incompatible light absorption and charge carrier diffusion lengths. Here, we have fabricated p-n Cu₂O homojunction nanocomposite by multiple steps of electrochemical deposition processing with the optimization of deposition periods. The p-Cu₂O/n-Cu₂O nanocomposite fabricated by optimized pH (4.9) and deposition time (4 min) exhibited double the photocurrent density of that of the bare p-Cu₂O photocathode. And the highest photocurrent density of nanostructured p-n Cu₂O nanorod homojunction photocathode with a p-Cu₂O blocking layer reached -10.0 mA cm^-2 at 0 V versus the reversible hydrogen electrode under simulated AM 1.5G illumination (100 mW cm^-2).