| dc.description.abstract | The photoelectrochemical (PEC) can directly utilize the photo-generatedelectron-hole pair in semiconductor electrode to catalyze the reaction like nature
through photosynthesis. If the biomass is used as the reactant for selectiveoxidation to generate a product of high economic value, it will be anenvironmentally friendly and energy-saving process. We tried to develop a
photoanode that absorbs visible light and applies it to the selective oxidation of 5-hydroxymethylfurfural (HMF). In this study, the BiVO4 thin film photoelectrode
was first prepared by spin coating, and the performance of the photoelectrode was
improved by coating a buffer layer, a protective layer, and a co-catalyst. The buffer
layer improves the properties of the BiVO4 structure, making the grain moreuniform and complete. At 1.2 V vs. RHE, the photocurrent is increased by 33%,and the IPCE is increased from 16% to 34% at 400 nm. Loading of the NiOx cocatalyst improves the oxidation kinetics, shifting the oneset potential to thenegative side by 0.2 V vs. RHE of the water splitting reaction, but the current in
the high-bias region is suppressed, indicating that there are also problems with theinterface and surface. The property of the protective layer TiO2 is similar to that
of a transparent conductive oxide (TCO), which can effectively reduce the
recombination of electron-hole pairs at the interface between the semiconductorand the electrolyte.
After that, we selected the BiVO4/SnO2 photoelectrode with the highestphotocurrent properties to test the stability under different electrolytes and pH
environments, and found that the borate buffer solution at pH=10 showed the best performance.
By using TEMPO as the mediator, we have demonstrated a electrochemicaloxidation of HMF into FDCA. When 78 C was passed, HMF had a conversion
rate of 74%, FFCA and FDCA had 29%, 30% yield, and 40%, 41% selectivity,Faraday efficiency is 91%. From the calculation of the concentration change, we
conclude that HMF is a first order reaction. | en_US |