TiO2/g-C3N4 photoanode prepared with polydopamine inspiration for photocatalytic fuel cells towards simultaneous wastewater treatment and electricity generation

Abstract

Photocatalytic fuel cell is a promising wastewater treatment technology, which can degrade pollutants and generate electricity simultaneously. However, the development of high-performance photoanode remains a challenge for photocatalytic fuel cells. Inspired by the bionic material of polydopamine, we propose to apply polydopamine to prepare the TiO2/g-C3N4 photoanode for enhancing the adsorption of protonated g-C3N4 nanosheets onto TiO2 via electrostatic interaction, which greatly promotes charge transfer and inhibits electron-hole recombination. Moreover, the polydopamine particles can be converted into plenty of pores during the calcination process, which enhances light scattering and mass transfer. Consequently, the TiO2/g-C3N4 photoanode prepared with polydopamine inspiration exhibits superior photoelectrochemical activity than the TiO2/g-C3N4 photoanode prepared without using polydopamine and the pristine TiO2 photoanode, presenting an improvement in the maximal power density by 8.7 % and 70.4 %, respectively. In addition, the effect of the adsorption time of the protonated g-C3N4 nanosheets is also studied. It is shown that an excessive amount of the protonated g-C3N4 nanosheets by increasing the adsorption time leads to more serious recombination and thereby decreases the photoanode performance. This study provides a novel and efficient way to prepare composite photoanode for photoelectrochemical applications.