Abstract
Il progetto NANOARC sviluppa nano-architetture fotoelettrocatalitiche innovative per processare coppie redox cruciali (H₂O/O₂ e CO₂/HCOOH) su superfici elettrodiche, contribuendo alla sfida dell’Artificial Photosynthesis per la produzione di energia rinnovabile. L’obiettivo è superare i limiti della fotosintesi naturale attraverso una riprogettazione che combini l’ossidazione foto-redox dell’acqua con la riduzione selettiva del CO₂ per produrre combustibili solari. Il progetto introduce un approccio modulare con blocchi organico-inorganici bio-ispirati, basati sulla chimica supramolecolare dei perylene-bisimidi (PBI) e poliometallati (POM) per l’ossidazione dell’acqua. Per la riduzione del CO₂, saranno sviluppati elettrocatalizzatori multifunzionali su nanostrutture di carbonio, utilizzando ossidi misti con vacanze di ossigeno. Gli elettrodi saranno assemblati in strati a diffusione di gas per ottimizzare il microambiente, mentre studi di fotoelettrocatalisi definiranno le relazioni struttura-reattività per realizzare una cella PEC innovativa per la produzione di acido formico da CO₂. Results Achieved Storage (20228YFRNL) The NANOARC project has achieved substantial progress towards the development of bio-inspired nanomaterials and photoelectrochemical architectures for artificial photosynthesis, with a specific focus on water oxidation and CO2 conversion into renewable chemical vectors. The consortium advanced the design, synthesis, characterization and integration of anodic and cathodic materials, maintaining full alignment with the original scientific objectives. For the cathodic side, the project developed several classes of CeO2-based multifunctional catalysts supported on carbon nanostructures, including oxidized carbon nanohorns, g-C3N4, carbon nanotubes, rare-earth-doped systems, and Bi- or Cu-containing composites. These materials were designed to improve CO2 adsorption, charge transfer and product selectivity through the control of oxygen vacancies, active phase dispersion and interfacial properties. The electrocatalytic tests confirmed the relevance of CeO2 oxygen vacancies and Ce3+ sites for CO2 reduction. CeO2@oxCNH catalysts reached up to 95% Faradaic efficiency for formic acid at -0.5 V vs RHE in H-type cells, while flow-cell and gas diffusion electrode configurations produced higher current densities and broadened the product distribution toward liquid products, including methanol and ethanol, with suppressed hydrogen evolution. CeO2/g-C3N4 catalysts showed strong selectivity to formic acid, reaching 69% Faradaic efficiency and 74 ppm h-1 mg-1 productivity, while rare-earth doping promoted C-C coupling and increased 1-propanol formation. Bi@CeO2/CNT catalysts further enhanced formic acid production, reaching about 350 mg/L after 3 hours, and in-situ EXAFS clarified the key role of Bi/BiOx interfaces interacting with CeO2. Preliminary Cu@CeO2/CNT results demonstrated the possibility of shifting selectivity toward ethylene and CO while retaining CeO2-related formic acid production. For the anodic side, the project successfully developed Photosystem-II-mimetic Artificial Quantasome photoanodes based on electrostatic self-assembly of bis-cationic perylene bisimides and Ru4POM water oxidation catalysts. PEG-based cross-linkers were introduced to tune hydration domains and proton transport within the supramolecular architecture. Structural studies by SAXS and low-field NMR revealed hierarchical water environments, while photoelectrochemical tests identified QSPEG-6 as the best-performing architecture. This system delivered a photocurrent increase of about +420% compared with the non-crosslinked reference, Faradaic efficiency for oxygen evolution above 95%, and a turnover frequency of 0.031 +/- 0.005 s-1 under visible irradiation. These results demonstrate that controlled hydration and supramolecular organization are key parameters for efficient proton-coupled electron transfer and reduced recombination losses. The project also made important advances in electrode engineering and surface characterization. Cathodic and anodic interfaces were optimized through control of morphology, active layer homogeneity, wettability and hydrophilic/hydrophobic balance. Raman, XRD, XPS, ATR-FTIR, AFM-Raman and contact-angle analyses supported the correlation between material structure, surface organization, oxygen vacancies and catalytic performance. These activities contributed to more reproducible electrode architectures and provided a solid basis for future device-level implementation. Overall, NANOARC has established clear structure-activity relationships linking nanomaterial composition, oxygen vacancy formation, supramolecular organization, hydration, mass transport and catalytic selectivity. The project produced significant dissemination outputs, including invited lectures, oral and poster presentations at international conferences, and several published or accepted papers. All activities were conducted in compliance with DNSH, Open Access, gender equality, generational balance and equal opportunity principles. No significant scientific changes to the approved project are required. Future work will focus on integrating the most promising photoanodes and cathodes into scalable photoelectrochemical devices, including flow cells and gas diffusion electrodes, with the long-term goal of developing efficient and durable artificial photosynthesis systems for solar fuel production.
Project details
Unibo Team Leader: Giovanni Valenti
Unibo involved Department/s:
Dipartimento di Chimica "Giacomo Ciamician"
Coordinator:
Università degli Studi di TRIESTE(Italy)
Total Unibo Contribution: Euro (EUR) 44.837,00
Project Duration in months: 24
Start Date:
16/10/2023
End Date:
28/02/2026
