Bismuth vanadate (BiVO4) is proven to be a promising photocatalyst for water splitting. However, the effect of materials syntheses, electrode preparation and size of photoelectrode on the photocurrent output of BiVO4 photoanodes needs further investigations. In this study, three different BiVO4 nanoparticle synthesis were employed, namely hydrothermal (HT), HT in the presence of ethylene glycol (EG) and HT with the addition of hydrazine hydrate (HH). In addition, two molecular inks (Triton-X and ethyl‐methyl‐imidazole, EMI), were compared for the preparation of BiVO4 photoanodes using a simple doctor-blade technique followed by calcination at 450°C. The photoanodes (9 cm2 active surface) were then compared for their photocurrent density at AM1.5G illumination and 1.2 V (vs . standard hydrogen electrode (SHE)) bias in a specifically designed, three-dimensional (3D)-printed electrochemical cell. The highest photocurrent 0.13 ± 0.1 mA cm–2 was obtained with the EMI ink, whereas tenfold lower photocurrent was obtained with Triton-X due to the higher charge transfer resistance, measured by electric impedance spectroscopy (EIS). The photoresponse was reproducible and relatively stable, with only 8% decrease in five consecutive illumination periods of 1 min.
We continue our review of recent research into oxides of platinum group metals (pgms), in particular those of ruthenium and iridium, for use as electrocatalysts for the oxygen evolution reaction (OER). In Part I (1), the electrocatalytic splitting of water to oxygen and hydrogen was introduced as a key process in developing future devices for various energy-related applications. A survey of ruthenium and iridium oxide structures for oxygen evolution reaction catalysis was presented. Part II discusses mechanistic details and acid stability of pgm oxides and presents the conclusions and outlook. We highlight emerging work that shows how leaching of the base metals from the multinary compositions occurs during operation to yield active pgm-oxide phases, and how attempts to correlate stability with crystal structure have been made. Implications of these discoveries for the balance of activity and stability needed for effective electrocatalysis in real devices are discussed.
