Production of Solar Fuels by Photoelectrochemical Conversion of Carbon Dioxide
[eng] Growing global emission of carbon dioxide gas (CO2) reflects the world’s energy dependence on fossil fuels. The conversion of CO2 emission into value-added products, like fuels completes a circular CO2 economy which requires a renewable energy conversion and storage system. Amongst a few, phot...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/112608 |
| Acceso en línea: | https://hdl.handle.net/2445/112608 http://hdl.handle.net/10803/404018 |
| Access Level: | acceso abierto |
| Palabra clave: | Electroquímica Diòxid de carboni Catàlisi Fotoelectroquímica Galvanoplàstia Electrochemistry Carbon dioxide Catalysis Photoelectrochemistry Electroplating |
| Sumario: | [eng] Growing global emission of carbon dioxide gas (CO2) reflects the world’s energy dependence on fossil fuels. The conversion of CO2 emission into value-added products, like fuels completes a circular CO2 economy which requires a renewable energy conversion and storage system. Amongst a few, photo/electrochemistry has been particularly appealing thanks to its energy efficiency and enormous potential for industrial applications. Formic acid (HCOOH) production from CO2 reduction appears as an alternative energy storage option based on the commercialization of this process. Herein, stable and selective catalysts working at low overpotential are needed to reduce CO2. Likewise, cell design is critical to have improved CO2 mass transport for obtaining high conversion efficiencies and to achieve feasible production yields. The initial work was conducted on the design and understanding of operational parameters of an electrochemical flow cell (ECf-cell) such as flow rates and electrode potentials. For CO2 reduction at the cathode site, two different gas diffusion electrodes were produced by electrodeposition: Sn-GDE and Cu-GDE. An optimum potential range was established to control HCOOH selectivity. The complementing reaction at the anode site, oxygen evolution reaction (OER), was studied using Mn-Co oxide nanoparticles to replace expensive DSA: Ir-Ta oxide catalyst. Subsequent efforts were devoted on the assembly of a photoelectrochemical flow cell (PECf-cell) which enabled coupling of Sn-GDE as cathode vs. TiO2 nanorods as photoanode. This led to nearly 1/3 reduction in overall cell voltage reaching an energy efficiency up to 70 %. The solar-to-fuel (STF) conversion efficiency was 0.25% which was one of the highest efficiencies reported amongst the data obtained from a cell in device level. The results proved that optimized system efficiency could be achieved with a large bandgap photoanode having superior stability and a GDE cathode with improved CO2 mass transfer. The deployment of renewable energy sources will require new technologies to emerge. The photoelectrochemical flow cell developed in this work can store energy from intermittent electricity sources (i.e. wind and solar) in a sustainable manner. This may pave the way for commercialization of this process and moving towards a circular CO2 economy. |
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