Development of CZTS-sensitized TiO2 nanoparticles via p-SILAR: concomitant salvaging of photocatalytic SnO2 and CZTS

Abstract

Pseudo-successive ionic layer adsorption and reaction (p-SILAR) process is performed on TiO2 nanoparticles for enhancing their visible light activity. Since p-SILAR is a facile process based on wet chemistry, it involves underutilization of ionic precursors which becomes even more adverse during the deposition of quantum dots having multi-cationic species in it. For example, copper zinc tin sulfide (CZTS) is deposited wet chemically by involving cationic precursors of Cu, Zn and Sn, respectively. At the end of the process, the left-over solutions are wasted owing to the decrease in purity and lowering of ionic concentrations those are hard to be traced. In this work, we have increased the photocatalytic response of TiO2 under visible irradiation by depositing CZTS quantum dots (QDs) on it, while on the other hand we recovered SnO2 and CZTS products (named as SnO2@p-SILAR and CZTS@p-SILAR, respectively) from the underutilized ionic precursors making process efficiency better. The SnO2 particles were separated from Sn-precursor owing to their precipitation during p-SILAR, while CZTS was separately produced via simple physico-chemical control. All the materials, whether synthesized or salvaged, were applied as photocatalysts for degrading toxic Rhodamine B (RhB) dye under ultraviolet or visible light. Compared with negligible performance of TiO2 (kC ~ 0.0011 min−1), p-SILAR synthesized TiO2–CZTS (kC ~ 0.01 min−1) and CZTS (kC ~ 0.0085 min−1) exhibited much higher pace in reaction that was credited to their higher absorbance of visible light.