One-pot fabrication of BiPO4/Bi2S3 hybrid structures for visible-light driven reduction of hazardous Cr(VI).

For the first time, a novel BiPO4/Bi2S3 heterostructures with different morphologies have been fabricated through a facile and rapid one pot precipitation route followed by anion-exchange strategy for the photoreduction of toxic Cr(VI) to harmless Cr (III). The hybrid structures systematically investigated using XRD, FE-SEM, EDS, TEM, HRTEM, XPS, FT-IR, UV-vis DRS, and PL. Changing the solvent type has a significant role for controllable morphologies of BiPO4/Bi2S3 hybrid as well as the catalytic activity. The BiPO4/Bi2S3 hybrid synthesized in diethylene glycol (DEG) performed the highest reduction efficiency of Cr(VI) within 20 min, compared with pure hexagonal phase of BiPO4 under visible light. The rate constant for BiPO4/Bi2S3 synthesized in DEG found to be 20.3 times larger than that for pure BiPO4. In addition, the presence of tartaric acid as hole scavenger could enhance the Cr(VI) reduction efficiency to 97.9%. No significant decrease in the catalytic efficiency after recycling up to four cycles. This promising study could present a significant approach towards Cr(VI) photoreduction from water through the novel BiPO4/Bi2S3 photocatalyst.

Facile fabrication of a novel BiPO4 phase junction with enhanced photocatalytic performance towards aniline blue degradation.

A novel BiPO4 photocatalyst has been fabricated via a facile precipitation route using dimethyl sulfoxide (DMSO) as a solvent. The physical and chemical properties of the BiPO4 photocatalyst material were analyzed using XRD, Rietveld refinements XRD, FE-SEM, TEM, HR-TEM, EDS, XPS, FT-IR, Raman spectra, UV-Vis (DRS), and PL. The results confirm that hexagonal phase BiPO4 (HBIP) nanorods were successfully synthesized. FE-SEM images reveal that the addition of surfactant "CTAB" during preparation can control the surface morphology of BiPO4. The Rietveld refinement technique revealed the formation of a monazite monoclinic (nMBIP) and monoclinic (mMBIP) phase junction resulting from the calcination of HBIP at 500 °C. The photocatalytic behavior of the as-synthesized hexagonal and monoclinic BiPO4 nanostructures towards aniline blue (AB) degradation under UV light was systematically investigated. Among all catalysts, the phase junction (nMBIP-mMBIP) structure demonstrated the highest photocatalytic activity. The degradation rate of AB over the (nMBIP-mMBIP) phase junction structure was 3.4 times higher than that by HBIP. These results suggested that the surface-phase junction provides a synergistic effect for the electron-hole transfer process.