Hematite Nanorods Photoanodes Decorated by Cobalt Hexacyanoferrate: The Role of Mixed Oxidized States on the Enhancement of Photoelectrochemical Performance

Autor(es)

Carminati, Saulo Amaral ^[1] ; da Silva, Bruno Leuzinger ^[1] ; Bott-Neto, Jose Luiz ^[1] ; de Melo Jr, Mauricio Alves ; Galante, Miguel Tayar ^[2] ; Fernandez, Pablo Sebastian ^[2] ; Longo, Claudia ^[2] ; Bonacin, Juliano Alves ^[2] ; Nogueira, Ana Flavia ^[2]

Afiliação do(s) autor(es)

^[1] Univ Campinas UNICAMP, Inst Chem, BR-13083970 Campinas, SP - Brazil

^[2] de Melo Jr, Jr., Mauricio Alves, Univ Campinas UNICAMP, Inst Chem, BR-13083970 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ACS APPLIED ENERGY MATERIALS; v. 3, n. 10, p. 10097-10107, OCT 26 2020.
• Citações Web of Science: 0

Resumo

In this work, we report on the incorporation of cobalt hexacyanoferrate (Co-NC-Fe) with different iron oxidation states (Fe-II and Fe-III) on hematite (alpha-Fe2O3) nanorod photoanodes with a systematic investigation of enhanced photoelectrochemical performance under a neutral pH. A detailed investigation using in situ techniques was carried out to understand the fundamental aspects of chemical reactions during photoelectrochemical characterization. The alpha-Fe2O3/Co-NC-Fe photoanodes showed a higher photoelectrochemical performance compared to the individual materials. Despite the higher achieved performance of alpha-Fe2O3/Co-NC-Fe, the elucidation of the main contribution upon Co-NC-Fe incorporation was found to be dependent on the different charge transfer mechanism under light illumination. Therefore, given the complexity of the redox processes that take place in Co-NC-Fe under an applied bias, we have systematically investigated the dark- and light-induced effects on alpha-Fe2O3/Co-NC-Fe by in situ UV-vis and Fourier transform infrared spectroscopies. These techniques allowed us to monitor the effect of the electro and photoelectrochemical potential in several redox processes. The insightful results indicate that, in addition to surface state modification effects, the improvement of the photocurrent density may also result from long-lived holes at the electrode surface as a consequence of the electron transfer from the conduction band alpha-Fe2O3 to Co-NC-Fe with a Fe-III oxidation state. This indicates a second electron pathway during charge separation, thereby contributing to the increase in the electron-hole pair lifetime and the accumulation of photogenerated holes at the alpha-Fe2O3/Co-NC-Fe photoanode surface to drive water oxidation. (AU)

• Processo FAPESP: 15/23775-3 - Nanocompósitos de óxidos metálicos com óxido de grafeno reduzido e suas aplicações em reações de water splitting e fotorredução de CO2
• Beneficiário: Saulo do Amaral Carminati
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 18/20952-0 - Estudos fundamentais e aplicados sobre conversão eletroquímica álcoois e CO2
• Beneficiário: Pablo Sebastián Fernández
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Regular
• Processo FAPESP: 17/11986-5 - Divisão de Pesquisa 1 - Portadores Densos de Energia
• Beneficiário: Ana Flávia Nogueira
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia
• Processo FAPESP: 17/23960-0 - Estudo de mecanismo de oxidação de água por catalisadores operando em pH=7 e sua incorporação em eletrodos impressos em 3D
• Beneficiário: Juliano Alves Bonacin
• Modalidade de apoio: Auxílio à Pesquisa - Regular