Surface photovoltage measurements: A quick assessment of the photocatalytic activity?

Surface photovoltage (SPV) measurements can contribute to a better understanding of electronic properties of photocatalysts under illumination. Direct linking of SPV data to the actual photocatalytic activity remains troublesome. This work aims to discuss SPV measurements from a photocatalytic point of view. By means of several application-based scenarios we illustrate that the trend between SPV and photocatalysis strongly depends on parameters such as the crystal structure, surface modifications, morphology and humidity. This makes the interpretation far from straightforward.

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► For TiO2 with variable rutile content reaction rate is proportional to surface photovoltage.
► In the range 0.1–1.0 at% Ag on TiO2, the reaction rate is inversely related to SPV.
► For three commercial catalysts the order of SPV response is P25 > P90 > PC500.
► Photocatalytic activity order in aqueous phase is P25 > P90 > PC500, but reversed in gas phase.
► Catalyst humidity has a large influence on the SPV signal.