Electrostatic Field Enhanced Photocatalytic CO_(2) Conversion on BiVO_(4) Nanowires

The recombination loss of photo-carriers in photocatalytic systems fatally determines the energy conversion efficiency of photocatalysts.In this work,an electrostatic field was used to inhibit the recombination of photo-carriers in photocatalysts by separating photo-holes and photo-electrons in space.As a model structure,(010)facet-exposed BiVO_(4)nanowires were grown on PDMS-insulated piezo-substrate of piezoelectric transducer(PZT).The PZT substrate will generate an electrostatic field under a certain stress,and the photocatalytic behavior of BiVO_(4) nanowires is influenced by the electrostatic field.Our results showed that the photocatalytic performance of the BiVO_(4) nanowires in CO_(2)reduction in the negative electrostatic field is enhanced to 5.5-fold of that without electrostatic field.Moreover,the concentration of methane in the products was raised from 29% to 64%.The enhanced CO_(2) reduction efficiency is mainly attributed to the inhibited recombination loss of photo-carriers in the BiVO_(4) nanowires.The increased energy of photo-carriers and the enhanced surface absorption to polar molecules,which are CO in this case,were also play important roles in improving the photocatalytic activity of the photocatalyst and product selectivity.This work proposed an effective strategy to improve photo-carriers separation/transfer dynamics in the photocatalytic systems,which will also be a favorable reference for photovoltaic and photodetecting devices.

Toward photocatalytic hydrogen generation over BiVO_(4) by controlling particle size

Owing to excellent light absorption and high activity fo r oxygen evolution,monoclinic bismuth vanadate(BiVO_(4)) is regarded as an ideal candidate for photocatalytic water splitting.However,its application is limited by the large particle size in micrometer scale,as well as the slightly positive conduction band.In this work,we successfully synthesized nano-BiVO_(4) with particle size ranged from 27 nm to 57 nm by wet chemical method based on electrostatic spinning method.Unlike bulk BiVO_(4),the nano-sized BiVO_(4) possesses the ability to generate hydrogen by water splitting,and the activity could reach up to1.66 μmol h^(-1) g^(-1) with the assistance of Pt.The enhanced activity is mainly attributed to the improvements resulted from reduced particle size,which includes elevated conduction band,enlarged specific surface area and promoted charge separation.This work provides a simple method for synthesizing photocatalyst with small particle size and high yield.

Pretreatment of polyvinyl alcohol by electrocoagulation coupling with catalytic oxidation:Performance,mechanism and pathway

In this study,various conditions for the removal of polyvinyl alcohol(PVA)by electrocoagulation(EC)coupled catalytic oxidation are systematically studied.The direct oxidation of the anode,the reduction of the cathode,the oxidation of·OH and·Cl,and the synergistic effect of flocculation on the degradation of polyvinyl alcohol are investigated.It is observed that the optimum experimental conditions obtained are as follows:Cell voltage 9 V,natural pH 7,NaCl concentration 0.02 mol/L,and interelectrode distance3.0 cm.The evolution of iron ions is also discussed in the EC process.By contrast,EC had made an outstanding contribution to the removal of PVA,which removes 71.29%of PVA.Free radicals,especially·OH and·Cl,are equivalent to the contribution of the electrodes in the degradation of PVA.And the contribution of PVA degradation by anode oxidation and cathode reduction are 12.76%and 8.02%,respectively.Characterization of solution and floc,such as Fourier transform infrared spectrometry(FTIR),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),thermogravimetric analysis(TGA),GC-MS and molecular weight,showed that PVA is effectively removed by the EC process,and a possible degradation pathway is proposed.