CHEMICAL ROUTES TO MATERIALS Multi-Photonic behavior of Nb 2 O 5 and its correlation with synthetic methods Ca´tia L. U ¨ cker 1, * , Vitor Goetzke 1 , Fa´bio C. Riemke 1 , Marcelo L. Vitale 1 , Lucas R.Q. de Andrade 1 , Maicon D. U ¨ cker 1 , Eduardo C. Moreira 3 , Ma´rio L. Moreira 1,2 , Cristiane W. Raubach 1 , and Se´rgio S. Cava 1 1 CCAF – Advanced Crystal Growth and Photonics, CDTEC, Technological Development Center, Federal University of Pelotas, UFPEL, Pelotas, RS 96010-610, Brazil 2 Physics Department, Federal University of Pelotas, UFPEL, Pelotas, RS 96160-000, Brazil 3 Spectroscopy Laboratory, Federal University of Pampa, UNIPAMPA, Bagé, RS 96413-172, Brazil Received: 7 September 2020 Accepted: 3 January 2021 Published online: 12 January 2021 Ó The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature 2021 ABSTRACT The performance of niobium pentoxide (Nb 2 O 5 ) as photoanodes in dye-sensi- tized solar cells (DSSCs) and as catalysts in the photocatalytic degradation of Rhodamine B (RhB) was investigated. Four samples of Nb 2 O 5 (Nb 2 O 5 _SG, Nb 2 O 5 _CR, Nb 2 O 5 _PP, and Nb 2 O 5 _MA) were synthesized by four different methods, respectively, entailing the sol-gel, combustion, polymeric precursors, and a microwave-assisted hydrothermal reaction. In all these samples, the orthorhombic phase of Nb 2 O 5 was obtained, which resulted in different shapes and assemblies, which is very relevant because the surface area, shape, and size distribution of the nanoparticles significantly contribute to the optical process. The bandgap remained constant at 3.0 eV for all the samples, even for the sample prepared by the combustion method. An additional phase, which is related to local distortions, was revealed by Raman spectroscopy within the vibration range of 688–260 cm -1 . DSSCs using photoanodes with smaller and more dispersed Nb 2 O 5 particles showed better results than those with inho- mogeneities. For comparison, DSSCs were assembled using two different counter electrodes, platinum and graphite. The DSSC with platinum showed better photovoltaic results, mainly with photocurrents from 1.17 mA.cm -2 for Nb 2 O 5 _CR to 1.64 mA.cm -2 for Nb 2 O 5 _SG. The same trend was observed for the photocatalytic degradation of RhB, where the smaller and dispersed particles of Nb 2 O 5 _CR and Nb 2 O 5 _SG exhibited the best performance and, respectively, degraded approximately 75% and 61% of the RhB dye over 180 min. Therefore, the results of this study established a correlation between the synthesis methods and photonic behavior. Handling Editor: Pedro Camargo. Address correspondence to E-mail: catiaucker@gmail.com https://doi.org/10.1007/s10853-021-05770-z J Mater Sci (2021) 56:7889–7905 Chemical routes to materials