Rational synthesis of BixFe1−xVO4 heterostructures impregnated sulfur-doped g-C3N4: A visible-light-driven type-II heterojunction photo(electro)catalyst for efficient photodegradation of roxarsone and photoelectrochemical OER reactions

Abstract

Metal vanadate (MVO4) and graphitic carbon nitride (g-C3N4) semiconductor materials have attracted much interest due to their tremendous physicochemical and photocatalytic performances. In this prospect, BixFe1–xVO4 were prepared by mixing cation precursors (Bi and Fe) in different proportions (x = 0.7; 0.5; 0.3) via a simple one-pot hydrothermal route and impregnated on the surface of sulfur-doped g-C3N4 (SCN) to attain a wide range of solar absorption and effective charge separation. Several spectroscopic techniques were used to analyze the physicochemical and optoelectronic properties of as-synthesized photocatalysts. The photocatalytic activities of as-synthesized photocatalysts were evaluated by photoelectrochemical oxygen evolution reactions (OER) and photodegradation of roxarsone (ROX). This work aims to investigate the formation, photocatalytic performance, and rational mechanism of BixFe1–xVO4/SCN photocatalytic nanocomposites. Among different BixFe1–xVO4 (x = 0.7; 0.5; 0.3), the Bi0.5Fe0.5VO4/SCN (Bi/Fe = 0.5) nanocomposite results in 85.66% of ROX photodegradation within 90 mins under visible-light irradiation. The photocatalytic performance of the nanocomposite is about 2.49, 2.87, 3.48 folds higher than that of pristine g-C3N4, BiVO4, and FeVO4 samples, respectively. The photoelectrochemical OER results suggest the higher photocurrent density at 1.23 V (vs NHE) was achieved by Bi0.5Fe0.5VO4/SCN (0.987 mA cm–2) nanocomposite, and which is 16.73, 5.11, and 6.16 times higher than that of CN (0.059 mA cm–2), BiVO4 (0.193 mA cm–2), and FeVO4 (0.160 mA cm–2), respectively. The XPS and photoelectrochemical (PEC) analysis depict the higher donor densities (ND) and excellent charge separations through type-II heterojunction of the BixFe1–xVO4/SCN nanocomposite.