Role of type II heterojunction in ZnO-In2O3 nanodiscs for enhanced visible-light photocatalysis through the synergy of effective charge carrier separation and charge transport

The field of ZnO based photocatalysis has seen a momentous leap in the past decade. However, the performance of pristine ZnO typically suffers from low photon absorption and high recombination of photoinduced charge carriers. Current work demonstrate that the development of well-crafted ZnO-In2O3 type II heterojunction can reduce the recombination rate and can boost the photon absorption ability simultaneously. The optimization of heterojunction was achieved by varying the composite ratio. The formation of heterojunction was confirmed through HRTEM analyses while the oxidation states of constituent elements were identified from the XPS study. The systematic photoelectrochemical study confirms the excellent interfacial electron-hole pair separation along with reduced charge transfer resistance through the interface of the heterojunction. The optimally designed ZnO-In2O3 heterojunction at 1:1 composite ratio exhibits an unprecedentedly high visible light active photo catalytic performance for the decomposition methylene blue than the other samples. The calculated rate constant of optimal photocatalyst was found to be 2.41, 2.52, and 1.76 times higher than the pristine ZnO under visible, solar, and under sonication mode respectively. In particular, current work displays a novel approach of exploring the role of composite ratio on ZnO-In2O3 type II heterojunction for improved photocatalysis through elevated photon absorption and effective charge carrier separation.