Effects of molecular modifications for water splitting enhancement of BiVO4. (29th May 2020) - Grądzka-Kurzaj, Iwona
Abstract: Combined organic (molecular adsorption) and inorganic (TiO2 passivation) modifications for enhancing water splitting efficiency of porous bismuth vanadate electrodes are tested. The catalytic activity of BiVO4 is increased after adsorption of a newly prepared ruthenium catalyst. TiO2 passivation and sensitization with RuP dye does not show straightforward improvements to the complex photocatalytic behaviour depending on the configuration of the (two- or three-electrode) photoelectrochemical cell, type of the experiment and sample aging. The time constant for electron transport in BiVO4 electrodes (in the range of seconds, revealed by electrochemical impedance measurements) was found to correlate with the stable photocurrent of the cells. The femtosecond transient absorption studies confirm the negligible effects of RuP on the population of the photoexcited carriers in BiVO4 . The transient absorption studies also show that the processes responsible for the differences in photocurrents of the modified BiVO4 samples occur on a time scale longer than the first nanoseconds. Highlights: Sensitization with ruthenium catalyst enhances the catalytic activity of BiVO4 . Modified BiVO4 photoanodes were studied in two- and three electrode cells. Processes longer than nanoseconds affects the photocurrents in modified BiVO4 . Time constant for the electron transport in BiVO4 correlates with the photocurrent.