Architecting a Double Charge-Transfer Dynamics InS/BiVO n-n Isotype Heterojunction for Superior Photocatalytic Oxytetracycline Hydrochloride Degradation and Water Oxidation Reaction: Unveiling the Association of Physicochemical, Electrochemical, and Photocatalytic Properties.

To surmount incompatibility provoked efficiency suppression of an anisotype heterojunction and to pursue an improved intrinsic photocatalytic activity by manipulating oriented transfer of photoinduced charge carriers, an InS/BiVO (1:1) n-n isotype heterojunction was fabricated successfully through a simple two-step calcination method, followed by a wet-chemical deposition method. The formation of an n-n isotype heterojunction was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy. The photocatalytic efficiency of the InS/BiVO catalyst was examined over degradation of oxytetracycline hydrochloride (O-TCH) and oxygen (O) evolution reaction. Consequently, an n-n InS/BiVO isotype heterojunction exhibits a superior O-TCH degradation efficiency (94.6%, 120 min) and O evolution (695.76 μmol, 120 min) of multiple folds as compared to the pure BiVO and InS solely. This is attributed to the proper band alignment and intimate interfacial interaction promoted charge carrier separation over the n-n isotype heterojunction. The intimate interfacial contact was confirmed by transmission electron microscopy (TEM), high-resolution TEM, and field emission scanning electron microscopy analysis. The proper band alignment was confirmed by Mott-Schottky analysis. The photoelectrochemical linear sweep voltammetric study shows a superior photocurrent density (269 μA/cm) for InS/BiVO as compared to those for pristine BiVO and InS, which is in good agreement with the photocatalytic results. Furthermore, the superior charge antirecombination efficiency of the n-n isotype heterojunction was established by photoluminescence, electrochemical impedance spectroscopy, Bode analysis, transient photocurrent, and carrier density analysis. The improved photostability of the heterojunction was confirmed by chronoamperometry analysis. An orderly corelationship among physicochemical, electrochemical, and photocatalytic properties was established, and a possible mechanistic pathway was presented to better understand the outcome of the n-n isotype heterojunction. This study presents an effective way to develop new n-n isotype heterojunction-based efficient photocatalysts and could enrich wide applications in other areas.