Photocatalytic fuel cell with N-CQDs electron warehouses mediated ZnIn2S4/tubular g-C3N4/Ti 2D/0D/2D photoanode for efficient organic pollutant degradation and electricity generation

In this study, N-doped carbon quantum dots (N-CQDs)/ZnIn2S4/tubular g-C3N4(TCN)/Ti photoanode was successfully prepared by a simple one-pot solvothermal method and silica sol drop coating method, which was assembled with CuxO/Cu cathode to construct photocatalytic fuel cell (PFC) to degrade organic pollutants and generate electricity. The photoanode material aims to promote the separation and uniform transfer of photogenerated electron through the synergistic effect of Schottky junction and S-type heterojunction of 0D quantum dots. The PFC with N-CQDs-doped photoanode possessed strong power generation capacity (71.10·μW-cm−2) and high photoelectric conversion efficiency (0.098 %), which were 1.72 and 1.94 times that of the PFC with ZnIn2S4/tubular g-C3N4/Ti photoanode. It degraded more than 95 % of rhodamine B, 83.44 % of tetracycline and 50.66 % of bisphenol A within 30 min. The excellent performance of the developed PFC is attributed to the synergistic effect of different heterojunction in photoanode, and the improvement of absorption and utilization of visible light by doping N-CQDs. Both free radicals (•OH, •O2−) and non-free radicals (h+, 1O2) were involved in the degradation process of pollutants. It is noteworthy that, due to the Schottky junction, the N-CQDs could act as electron warehouses to promote the production of H2O2, which could enhance the degradation effect. We believe that this research provides a new direction for the development and research work on efficient photoanodes.