Fabrication of novel polyaniline/ZnO heterojunction for exceptional photocatalytic hydrogen production and degradation of fluorescein dye through direct Z-scheme mechanism

In the recent years, direct Z-scheme heterojunctions exhibit an exceptional reactivity in various photocatalytic processes. Hybrid visible light driven photocatalyst consisting of semiconducting metal oxide and conducting polymer have immense capability of destruction of various organic pollutants and production of hydrogen gas as alternative renewable energy source. Herein, a novel hybrid polyaniline/ZnO heterojunction were synthesized by coupling sol-gel and oxidative polymerization of aniline in ultrasonic bath of various intensities for removal of fluorescein dye and producing large amount of hydrogen gas under visible light source. Particularly, the amount of polyaniline plays a pivotal role in optimizing the amount of hydrogen gas produced. The change in the diffraction pattern of Wurtzite ZnO nanoparticles and the remarkable reduction of PL signal intensity suggest the construction of direct Z-scheme heterojunction. The photocatalytic hydrogen production rate estimated on the optimized sample using methanol as scavenger is 9.4 mmolh−1g−1 which is higher than that of bare ZnO nanoparticles. The sample containing 5 wt% polyaniline exhibits photocatalytic degradation rate of fluorescein dye 0.021 min−1 which is ten folds higher than that of bare ZnO. The results of our research work indicate that polyaniline is efficiently enhances the light absorption and providing an additional electrons that combine with H+ to produce H2-gas.