Protonated g‑C3N4 Nanosheets/N-Doped TiO2 Photoanode Prepared with Inspiration by PDA Microspheres for Photoelectrochemical Cells

Development of a highly performing heterojunction photoanode is significantly important for photoelectrochemical cells. Herein, a novel strategy is proposed to construct a protonated g-C3N4 nanosheets/nitrogen-doped TiO2 photoanode inspired by polydopamine microspheres. The polydopamine microspheres can enhance the adsorption of protonated g-C3N4 nanosheets via electrostatic interaction, facilitating heterojunction formation. Moreover, the addition of the polydopamine microspheres into the preparation process can not only dope a nitrogen element into TiO2, improving solar energy utilization, but also create a vigorous pore structure in the photoanode, promoting mass transport and light scattering. Besides, the specific surface area can also be increased. Owing to these merits, the photoelectrochemical activity of this newly developed photoanode is greatly improved. Furthermore, the superiority of this photoanode is evaluated by integrating it into a photoelectrochemical cell for simultaneous wastewater treatment and power generation. The maximum power density generated by the newly developed protonated g-C3N4 nanosheets/nitrogen-doped TiO2 photoanode is about 138.5% and 40.9% higher than the TiO2 photoanode and the protonated g-C3N4 nanosheets/TiO2 photoanode prepared without using the polydopamine microspheres, respectively. The present study provides a novel strategy for developing a highly performing heterojunction photoanode.