CavityMicroTips (CM_T) for the investigation of photocathode materials

The H2 production by photoelectrochemical water splitting is one the main goals in solar energy conversion studies. While the photoelectrocatalytic system for the oxygen evolution reaction (OER) requires the combined contribution of photoconverter and OER-electrocatalysts, the hydrogen evolution reaction (HER) could in principle be achieved using the p-type Cu2O photocatalyst alone, as discussed in [1] in terms of performances of electrodeposited thin p-Cu2O layers. In the present communication we report preparation and characterisation of different photoelectrocatalyst as disperse phase materials, with the aim of overcoming the intrinsic instability of Cu2O photoconverter and to increase the rate of hydrogen production. The test are performed by conventional voltamperometric techniques and by SECM in the tip generation/substrate collection mode,. Here a cavity micro-electrode is used as tip (CM_T) [2], in lieu of the usual disk, as support for the nanoparticles. As pointed out in previous works [2,3,4], cavity micro-electrodes present several advantages, and in particular the unique feature of eliminating the use of any gluing agent or additive to avoid any loss of material as in conventional electrode supports. In addition they can be easily emptied and refilled with new samples for screening between different materials and for reproducibility tests. [1] A. Paracchino, J. C. Brauer, J.-E. Moser, E. Thimsen, M. Graetzel, J Phys Chem C, 116 (2012) 7341-7350 [2] S. Morandi, A. Minguzzi, submitted [3] C. Locatelli, A. Miguzzi, A. Vertova, P. Cava, S. Rondinini, Anal. Chem. 83 (2011) 2819-2823 [4] A. Minguzzi, C. Locatelli, O. Lugaresi, A. Vertova, S. Rondinini, Electrochim. Acta 114 (2013) 637-642 A. K. Satpati, A. J. Bard, Anal. Chem. 84 (2012) 9498−9504