Organic/Inorganic Hybrid Photoelectrodes for sustainable CO2 reduction

Project Information

HyPhoCO

Grant agreement ID: 101030782

DOI

10.3030/101030782

Project terminated on 31 December 2022

EC signature date 25 March 2021

Start date 1 January 2022

End date 31 December 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 160 932,48

EU contribution

€ 160 932,48

Coordinated by

Fundacion IMDEA Energia
Spain

Periodic Reporting for period 1 - HyPhoCO (Organic/Inorganic Hybrid Photoelectrodes for sustainable CO2 reduction)

Reporting period: 2022-01-01 to 2023-12-31

Summary of the context and overall objectives of the project

This Marie Skłodowska Curie Action (MSCA) is titled “Organic/Inorganic Hybrid Photoelectrodes for sustainable CO2 reduction”. As detailed in the DoA, HyPhoCO aims at the bottom-up development of robust, high-performance photocathodes for CO2 reduction, based on abundant and non-toxic conjugated porous polymer (CPP) and CPP/Cu-oxides hybrid materials. Using a fundamental research approach, the design of CO2 reduction photocathodes has been based on a thorough investigation of the electronic structure and charge transfer dynamics of the PEC CO2 reduction process. This major goal was proposed to be addressed by completing three specific: (1) design, synthesis and preparation of CPP and CPP/Cu-oxides hybrid photoelectrodes for optimum PEC CO2 reduction; (2) development of comprehensive descriptions of structure-performance relationships for CPPs and hybrid CO2 reduction photoelectrodes. (3) Assignment of overall efficiencies for CO2 reduction photoelectrochemical cells based on optimum CPP and hybrid photocathode.

There are 3 major innovative concepts in HyPhoCO: (i) the development of a photoelectrochemical cell for CO2 reduction, therefore using CO2 (which is the most abundant greenhouse gas) as raw material, (ii) developing a technology largely based on functional polymers, which are materials largely abundant and free of geopolitical constraints, and (iii) development of single-site electrocatalysts for the CO2 reduction, a very valuable catalytic approach but poorly studied for the electrochemical CO2 reduction. These three innovative concepts contribute to addressing two main challenges humanity faces in the 21st century: (1) mitigation of climate change and (2) developing sustainable energy technologies.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The major research activities in this period included the preparation of CPP thin films by means of electrochemical deposition. As depicted in the figure attached, two series of thienyl-benzene and thienyl-BODIPY compounds were synthesised in order to use them as monomers precursors of polymer thin films. The successful preparation of high-quality BODIPY-based CPP thin films is a milestone in the HyPhoCO project because these materials have a strong visible-light absorption and are therefore very interesting for photoelectrochemical applications. In this sense, a detailed characterisation of the optoelectronic properties was carried out based on UV-visible and photoelectron spectroscopies, as well as impedance spectroscopy. An initial assessment of the PEC properties was also carried out.

This characterization work has led to the elucidation of band gaps and surface chemistry of CPP thin films. Elucidation of the electron energetics in CPP thin films, so that comprehensive band alignments between polymers and Cu-oxides, as well as redox pair, can be evaluated. BODIPY-based CPP thin films behave as photocathodes (ideal for carrying out reduction reactions), with large photo-potentials up to 0.5 V. Additionally, the energy positions of the conduction band found in all polymer-based electrodes are generally higher than the redox pair for CO2 reduction to CO, formate and CH4, therefore showing great potential for the use of these materials as photocathode for the PEC reduction of CO2.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

A major novelty aspect of the scientific work carried out so far in HyPhoCO is the pioneering evaluation of CPPs and CPP/inorganic hybrid materials as photoelectrodes. Despite their potential, CPPs studies have been limited to catalytic and photocatalytic applications. Therefore, results from this action will also work as guidelines for other PEC applications of these sustainable materials. Moreover, the achieved milestone related to the thin film processing of CPPs is considered an important material engineering aspect, highly in demand for the development of organic electronics beyond PEC system. Therefore, these results are identified as a reference for the increase of innovation capacity and diversification of companies in the energy and electronics sectors, in particular, because the studied CPPs and hybrid materials in this action are largely available, non-toxic and free of geopolitical constraints, which are crucial aspects for the scaling and commercialization of PEC technologies. Additionally, the descriptions of structure-performance relationships for CPPs and hybrid photoelectrodes achieved so far can be used as a basis for further industrial development towards the commercialization of environmentally friendly PEC systems for energy conversion. This way, the work done in the HyPhoCO project contribute to addressing two of the biggest challenges that humanity is facing in the 21st century: mitigation of climate change and development of sustainable energy technologies.

Polymer building blocks (top), picture of a CPP thin film and CuO made by electrodeposition