Tailoring photoactive nanoceramics over conductive substrate for solar water splitting application

Flavio Leandro de Souza
Laboratório Nacional de Nanotecnologia (LNNANO), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM)
Centro de Ciências Naturais e Humanas (CCNH), Federal University of ABC (UFABC)

Flavio L. Souza has a B.Sc. in Physics and obtained his PhD in Materials Science and Engineering from the Federal University of São Carlos. Thereafter, he worked as a Research Fellow in the Interdisciplinary Research Group of Prof. Leite, E.R. at the Nanocharacterization Laboratory in Chemistry Department at Federal University of São Carlos. He was a visiting professor (2016-2017) at Peter a Rock Thermochemistry laboratory, University of California, Davis, at Prof. Ricardo Castro and Alexandra Navrotsky group. Currently, Prof. Souza is Head of the Synthesis Division at Brazilian Nanotechnology National Laboratory (LNNANO), Associate Professor at Federal University of ABC and Member of Academic Affairs and Young Professional. Committee MRS, USA. He serves as senior Editor for Materials Letters journal (Elsevier). He has published more than 70 research articles in international journals, edited two books (published by Springer-Nature) and served as a referee for international journals as well as for major funding agencies abroad. His main research interests include the design and characterization of nanostructured semiconductors and ion-conducting polyelectrolytes for application in photo-and-
electrochemical devices.

RESUMO

Nanostructure design faster becomes a key factor in the race for enhancing the photoelectrochemical device performance, because it may lead to a reduction of the charge recombination rate by ensuring an efficient photogenerated charge separation. This talk will describe a simple chemistry manipulation of the polymeric precursor solution preparation that succeeded in creating back-contact rich interface between the commercial fluorine doped tin oxide coated glass (FTO) and nanoceramic photocatalyst layer. Nanoscale analysis revealed that the stress between FTO- nanoceramic photocatalyst at back contact interface during the fabrication process can be alleviated by combining Zr4+ addition and manipulating the polymeric precursor solution. This result will have an important impact in the effective charge
injection through the back-contact interface by partially mitigated the shunting recombination regularly observed in mesoporous materials (reducing the FTO exposition to the electrolyte). Chemical mapping analysis was conducted during the nanoscale investigation by scanning transmission electron microscopy showing that the Zr4+are distributed through the samples and preferentially segregating at hematite grains. Photoelectrochemical performance recorded at front-side illumination increases with Zr4+ concentration, which can be associated with a reduction in the energy barrier between the grains provoked by Zr4+presence and owned by a change in the surface chemistry. Indeed, evaluating the obtained nanoceramic photoelectrodes from microscopic to nanometric scale, the individual role of the modifiers, morphology formation and back-contact interface issue were unveiled confirming that the adopted strategy has potential to be used towards wide range of system from academic to industrial scale.