Screening of Photocatalysts by Scanning Electrochemical Microscopy

A method for rapid screening of photocatalysts employing a form of scanning electrochemical microscopy (SECM) is described. A piezoelectric dispenser was used to deposit arrays composed of ∼300-μm-size photocatalyst spots with different compositions onto conducting glass, fluorine-doped tin oxide substrate. The scanning tip of the SECM was replaced by a fiber optic connected to a xenon lamp and was rapidly scanned over the array. In this arrangement, the photocatalytic performance of the spots was evaluated by measuring the photocurrent at the substrate of the array. A fiber optic with a ring electrode can also be used to electrochemically detect products of the photoreaction. Several iron oxide-based bimetallic oxide combinations were found to exhibit enhanced photocatalytic activity, when compared to pure α-Fe₂O₃. These combinations included iron−palladium, iron−europium, and iron−rubidium in specific ratios. A trimetallic bismuth−vanadium−zinc oxide combination was also found to show a higher photocurrent, by ∼40%, compared to BiVO₃.