Synthesis of Nanosized Cobalt Oxides and Application in a Bio-hybrid Photoelectrochemical Cell for CO₂ Utilization

CO₂ capture and utilization (CCU) can alleviate the disastrous effects of greenhouse gas (GHG) emissions form the use of fossil fuels. The use of CO₂ emission as feedstock for direct conversion into valuable chemicals has attracted increasing research interest worldwide. A number of approaches, such as chemical, electrochemical, photochemical and biological routes have used CO₂ as a sustainable carbon resource for the production of chemicals. In the present CO2BioPEC project, a novel hybrid photoelectrochemical concept, based on solar energy and formate dehydrogenase biocatalyst is applied, as illustrated in Figure 1 (left). This multidisciplinary project aims at demonstrating a bio-hybrid photoelectrochemical cell, in which solar energy is efficiently captured and utilized to convert CO₂ into energy-rich compounds, using formate dehydrogenase enzymes as biocatalysts.
Cobalt oxide is a low-cost material with a band gap that can absorb visible light. It is also a promising co-catalyst that has been widely used for oxygen evolution route. In the present work, nanosized cobalt oxide was synthesized and used as a co-catalyst on the photoanode. The results showed that the formation of cobalt oxides (Co3O4, CoOOH and Co(OH)2) is strongly dependent on the temperature and reaction time. The photochemical efficiency will be further investigated by impregnating nanosized cobalt oxides onto Ta3N4 /TaON nanotubes.