Solar-driven wastewater treatment coupled with hydrogen and electricity production via a bismuth-doped TiO2 nanorod array

Abstract

An ingenious and unassisted solar-driven wastewater resourcezation system (SDWRS) was designed by connecting a silicon cell (SC) to the back of a bismuth-doped TiO2 nanorod array (BTNR) for efficient water treatment accompanying hydrogen and electricity generation. Doping of Bi effectively improved the charge-transfer property and donor density of the BTNR. In addition, the introduction of SC provided an inner bias much higher than conventional photocatalytic fuel cells (PFCs) to drive efficient electron transfer from the photoanode to cathode by absorbing the transmitted longer wavelength photons. Therefore, compared with pure TNR, the photocurrent density of BTNR at 0.8 V vs Ag/AgCl is greatly increased to ∼2.81 mA cm−2. Due to the enhanced light utilization and charge transfer, which derived from the synergistic effect between the BTNR and SC, the assembled SDWRS displayed the outstanding tetracycline (TC) degradation together with hydrogen and electricity production. A TC removal ratio of nearly 100% after 2.5 h of operation, an average hydrogen generation rate of ∼29.08 μmol h−1 cm−2, and an electricity output with a maximum power output of ∼632.8 μW cm−2 were achieved. The results also manifested that SDWRS had great application potential for degrading various refractory pollutants from wastewater for clean energy production.