Al doping promoted photocatalytic degradation of tetracycline hydrochloride on CuInS2 QDs assembly

Abstract

Doping plays key roles in tailoring morphologies or electronic structure of ternary alloyed CuInS2 (CIS) nanocrystals, aiming toward efficient photocatalytic performance. Here, aluminum ions (Al3+) were used as dopants to prepare aluminum ion-doped CIS (Al-CIS) quantum dots (QDs) via a hydrothermal route. By controlling the doping amount of aluminum and growth kinetics, sheet-like Al-CIS were prepared. TEM, HRTEM, and EDX results confirm the 2D meso-crystal structure of the Al-CIS, which was built by Al-CIS QDs via the same crystal orientation. The 2D meso-crystal combines the enlarged bandgaps of QDs with the high conductivity of single crystals, exhibiting higher photocurrent response and lower resistance than CIS QDs or Al-CIS QDs. As result, the 2D meso-crystals exhibit tetracycline (TC) degradation rates 2.5 times higher than that of coarsened CIS QDs, with excellent TC removal ratio of 96.2%. Kinetic investigations on TC degradation indicate that superoxide radicals (·O2-) dominate the process of TC oxidation. Mott-Schottky and band analysis suggest that the formation of 2D meso-crystal of Al-CIS increases carriers’ concentration in the conduction band, and lowers the position of the conduction band, favoring electron transfers toward reactants for boosting TC degradation.