Ag-functionalized Bi2W(Mo)O-6/PVDF membrane for photocatalytic water treatment

Costly and time-consuming recovery of photocatalysts from treated water is one of the main challenges for the photocatalysis process. In this regard, an Ag-functionalized Bi2W(Mo)O-6 photocatalyst was successfully synthesized via a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal method, immobilized on a polyvinylidene fluoride (PVDF) membrane and subsequently used for photocatalytic water treatment. The flower-like Ag-decorated Bi2W(Mo)O-6 photocatalyst revealed a significant enhancement (62%) in the photocatalytic degradation efficiency compared to the unmodified pure Bi2WO6(19%) due to the synergic contribution of the flower-like morphology with higher surface area, decrease in band gap by Mo doping and Ag-induced surface plasmon resonance (SPR) effects. In order to immobilize the photocatalyst, the Ag-decorated Bi2W(Mo)O-6 nanoparticles were distributed uniformly on the surface of the PVDF membrane. The results illustrate that the as-prepared Ag-loaded Bi2W(Mo)O-6/PVDF composite membrane effectively degrades the organic molecules (51%) without any additional process for the photocatalyst separation, confirming its potential as a beneficial environmental-friendly material for water treatment applications

Designing 1D plasmonic Ag/CuWO4 nanocomposite for enhancing visible-light photoelectrochemical performance

We report the synthesis and characterization of CuWO4, its functionalization with plasmonic Ag nanostructures and its photoelectrochemical properties. First, a solution-phase polyvinylpyrrolidone (PVP)-assisted approach was used to prepare shape-controlled plasmonic Ag (nanoparticles (NPs) and nanowires (NWs)) via heterogeneous nucleation. The growth process and morphological tuning of the as-synthesized Ag nanostructures were investigated experimentally. Molecular dynamics (MD) simulations were used to understand the underlying principles that govern nanowire growth by analyzing the interaction energies between crystal surfaces and PVP as well as the atom density profile. Significant enhancements of the photocurrent (45% and 140%, respectively) at the thermodynamic potential for oxygen evolution (0.62 V vs Ag/AgCl) were obtained for Ag NP/CuWO4 (0.11 mA cm(-2)) and Ag NW/CuWO4 (0.18 mA cm(-2)) photoanodes, respectively, compared to pristine CuWO4 photoanode. Moreover, the incorporation of Ag NWs significantly enhances the incident photon to current conversion efficiency (IPCE) across the 350-550 nm spectral range, revealing a maximum around 10%. The obtained improvement is attributed to improved light harvesting by Ag-induced surface plasmon resonance (SPR) effects with a dual peak absorption, together with more effective charge carrier transfer/separation. Therefore, incorporation of the as-prepared plasmonic nanostructures with CuWO4 causes a considerable improvement of the photoelectrochemical activity for energy conversion/storage applications

Photocatalytic Activity of ZnV2O6/Reduced Graphene Oxide Nanocomposite: From Theory to Experiment

A nanocomposite of ZnV2O6 with hierarchical flower-like structure hybridized with reduced graphene oxide (rGO) was fabricated using a facile hydrothermal approach. The structure, morphology, optical and electronic properties were explored using comprehensive analytical techniques. The results revealed that the rGO sheets were decorated with the in situ-formed ZnV2O6 nanoparticles yielding a well-combined composite structure. The photocatalytic activity of as-prepared ZnV2O6/rGO hybrids is 2.48 times larger than that of pristine ZnV2O6 for the degradation of Rhodamine B (RhB). In parallel to the experimental results, the basic mechanisms of interfacial interaction, charge transfer/separation and subsequently their influence on the photocatalytic activity were theoretically studied by first-principles calculations. The photocatalytic enhancement is attributed to efficient interfacial electron transfer from ZnV2O6 to rGO, leading to a prolonged lifetime of photoinduced charge carriers. We anticipate that these results will lead to new insights in the judicious design of graphene-based semiconductor photocatalysts

Mo-doped ZnV2O6/reduced graphene oxide photoanodes for solar hydrogen production

We report the fabrication and characterization of molybdenum (Mo)-doped ZnV2O6/reduced graphene oxide (rGO) composite and its use as photoanode for photoelectrochemical (PEC) hydrogen production. Compared to pure ZnV2O6, Mo ions act as electron donor in the ZnV2O6:Mo lattice increasing charge carrier concentration and subsequently mobility in the bulk by the polaron transport. We measured the hole transfer efficiency for the pure and Mo-doped ZnV2O6 electrodes and revealing a substantial increase from 16 to 25%. The mechanism of enhanced photoactivity of Mo-doped ZnV2O6 was studied by density functional theory calculations. Moreover, electrochemical impedance spectroscopy measurements show that graphene modification improves carrier separation and transfer across the electrode/electrolyte interface. Therefore, the combination of the two strategies triggers a synergistic enhancement in PEC performance in terms of incident photon-to-current efficiency, which is 17% at 370 nm, being 4.5- and 3.6-times greater than those of pristine ZnV2O6 and ZnV2O6:Mo photoanodes, respectively. With photocurrent onset potentials of 0.6 V and photocurrent densities of 2.07 mA/cm2 at 1.23 V vs. RHE, ZnV2O6:Mo/rGO photoanodes are of interest for the design of high performance PEC visible-light-induced water-splitting devices