Tungsten Sulfide Co-Catalyst Produced via Ammonium Paratungstate For Efficient Organics Degradation

Photocatalytic fuel cell (PFC) has been considered as an alternative strategy due to efficient wastewater treatment and simultaneous energy recovery. However, conventional PFC system is enslaved to the unsatisfactory performance due to the limited surface area of electrodes where the main radical reactions principally occur. To resolve this issue, the radical chain-reaction is introduced into the PFC system with the addition of Fe2+/Fe3+ recycling catalysts.

A new tungsten sulfide (WS2) co-catalyst prepared from ammonium paratungstate for efficient organics degradation was reported via introducing WS2 co-catalyst to increase the available Fe2+ for organic pollutant degradation and simultaneous energy recovery. Preparation process of the WO3/PVC composite photoanode can be concluded as below:

First, the WO3 photoelectrode was prepared by a typical hydrothermal synthesis method. 1 g of ammonium paratungstate (APT, (NH4)10(H2W12O42) ·4H2O), 2 mL HCl and 4 mL H2O2 was successively added into 94 mL deionized water. For each substance added into the aqueous solution, 1 h of stirring was required to dissolve them, which meant 1 h stirring should be repeated for three times for APT, HCl and H2O2, respectively. After these stirring processes, we got the transparent light yellow solution, which was transferred to an autoclave with the thoroughly rinsed FTO-coated glass (2.5 cm × 5 cm) in it. The hydrothermal process was conducted in a drying oven at 160 °C for 240 min. Finally, the prepared electrode was annealed at 500 °C for 2 h to crystallize the WO3.

Then, the as-prepared WO3 related to the rear Silicon PVC (2.5 cm × 4 cm, tri-cell by using copper wire and high purity silver paint (SPI Supplies, USA) as literature. Finally, the WO3/PVC composite photoanode was fabricated for the self-bias radical chain-reaction PFC system.

In summary, a tungsten sulfide (WS2) co-catalytic radical chain-reaction for enhanced PFC performance to efficiently degrade organics and simultaneously generate electricity. In the tungsten sulfide molecule, the exposed W4+ has the reductive capability, which could provide electrons to convert Fe3+ to Fe2+ and thus promote the radical chain-reaction. Taking advantage of the enhanced radical chain-reaction, the degradation rate constant was highly increased by 63.1 % and 222 % in the FeSO4/WS2/Pt system and FeSO4/WS2/GF system, respectively.

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