Improvement of the properties of bimetallic nanoparticles for application in artificial photosynthesis

• Grant number: 24/07242-4
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2024
• End date: October 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Abner de Siervo
• Grantee: Abner de Siervo
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The increase in the concentration of CO2 in the atmosphere causes the greenhouse effect. The Paris Agreement aims to achieve carbon neutrality by 2050. It is possible to transform CO2 into C2+ products (hydrocarbons with two or more C atoms), which are used as raw materials for clean and renewable energy sources and in the fine chemicals industry. Still, traditional methods have high energy costs and are dependent on finite fossil fuels. A clean and ambitious alternative is to use solar energy to carry out artificial photosynthesis, where CO2 and H2O react to form C2+ products. Metal-organic frameworks (MOFs) present good results in this reaction. Still, they are typically not stable in water or, when stable (such as MIL-101(Cr)), they are inactive due to their low light absorption in the visible region. The main challenge to be addressed is to increase the low efficiency and selectivity of MIL-101(Cr) for C2+ products and, therefore, produce a differentiated material for artificial photosynthesis. To increase the absorption of visible light in MIL-101(Cr), metallic nanoparticles with tunable plasmons can be introduced to produce the effect known as Localized Surface Plasmon Resonance (LSPR). This effect creates a very intense electromagnetic field on the surface of the nanoparticles, which should increase the absorption of light by MIL-101(Cr). The formation of core-shell or alloy nanoparticles allows regulating the binding energies of the molecules on the surface (selectivity of the nanoparticles) and the LSPR effect (selectivity of MIL-101(Cr)), which can also be altered by changing the shape of the nanoparticle. Cu is one of the few metals that can reduce CO2 to C2+ products with high selectivity, while Ag has intense plasmons in the visible region. Thus, using Cu-Ag nanoparticles with variable shapes and atomic arrangements supported on MIL-101(Cr) is highly promising and attractive for artificial photosynthesis because they are cheap and abundant metals. The present project aims to develop materials with differentiated performance for the artificial photosynthesis reaction with the consequent detailed investigation of the effects that directly influence the activity and selectivity of the materials produced for forming C2+ products during artificial photosynthesis. An approach with state-of-the-art experimental techniques (AP-XPS, AP-GIXS, STM, TERS) will be used to investigate real systems and model systems consisting of or representing Cu-Ag nanoparticles on a MOF network. This will enable the design of future materials with different properties for the artificial photosynthesis reaction. (AU)