Efficient solar hydrogen production coupled with organics degradation by a hybrid tandem photocatalytic fuel cell using a silicon-doped TiO2 nanorod array with enhanced electronic properties.

A novel, unassisted, hybrid tandem photocatalytic fuel cell (HTPFC) is constructed by adhering a silicon solar cell (SSC) to the back of a highly-active silicon-doped TiO2 nanorod array (STNR) for efficient solar hydrogen production coupled with organic compound degradation. The STNR with vertically arranged nanorods is prepared by a facile hydrothermal method and has improved charge transport properties and donor density due to the homogenously distributed silicon in the TiO2 matrix. As a result, the STNR has a notably enhanced photocurrent density that is as high as ˜0.76 mA cm-2 at 0.2 V vs Ag/AgCl, which is ˜271% of the photocurrent density of undoped sample. By combining the intriguing features of the STNR and SSC, the HTPFC shows a superior performance for tetracycline degradation and hydrogen production, with a removal ratio of 94.3% after 1.5 h of operation and an average hydrogen generation rate of ˜28.8 μmol h-1 cm-2. Compared to conventional PFCs, HTPFCs have improved light absorption and charge transfer, owing to the synergistic effect between the STNR and SSC. The results also indicate that the HTPFC is highly flexible, adaptable, and stable when treating wastewaters with various organics, and a wide range of pH values and salinities.