Tetragonal/orthorhombic-bismuth tungstate homojunction formed through in situ bismuth induced phase transformation as highly efficient photocatalyst for pollutant degradation

Tetragonal/orthorhombic-bismuth tungstate (t/o-Bi2WO6) homojunctions of high photocatalytic efficiencies were fabricated through a novel in situ Bi induced phase transformation. The photocatalytic efficiencies of t-Bi2WO6 were greatly enhanced via formation of the homojunction. Photocatalytic degradation of rhodamine B (RhB), a recalcitrant organic pollutant, under simulated sunlight illumination was investigated as a demonstration for the efficiency enhancement. A 6.22 folds improvement was achieved with formation of the homojunction in terms of reaction rate constants. The homojunction catalyst was demonstrated to be photocatalytically stable over a five cycles operation. The t/o-Bi2WO6 homojunction enhances separation and utilization efficiency of photo-generated charge carriers and thus greatly boosts the catalytic efficiency. Trapping tests and electron spin resonance spectroscopy were conducted to reveal that singlet oxygen (O-1(2)), hole (h(+)), electrons (e(-)), and superoxide anion radical (center dot O-2(-)) are the main working reactive species for RhB degradation. Density functional theory (DFT) calculations were performed to prove the feasibility of Bi induced phase transformation of t-Bi2WO6 to o-Bi2WO6. The present development offers a new design route for high efficiency photocatalysts for water pollution control. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

The high photocatalytic efficiency tetragonal/orthorhombic-bismuth tungstate (t/o-Bi2WO6) homojunctions were fabricated through a novel Bi induced phase transformation method. The homojunction catalyst enhances separation and utilization efficiency of charge carriers, greatly boosting the catalytic efficiency, and proving to be stable over multiple cycles of operation.