Artículos SCI

The surface chemistry and inter-connectivity within perovskite nanocrystals play a critical role in determining the electronic interactions. They manifest in the Coulomb screening of electron-hole correlations and the carrier relaxation dynamics, among other many-body processes. Here, we characterize the coupling between the exciton and free carrier states close to the band-edge in a ligand-free formamidinium lead bromide nanocrystal assembly via two-dimensional coherent spectroscopy. The optical signatures observed in this work show: (i) a nonlinear spectral lineshape reminiscent of Fano-like interference that evidences the coupling between discrete electronic states and a continuum, (ii) symmetric excited state absorption cross-peaks that suggest the existence of a coupled exciton-carrier excited state, and (iii) ultrafast carrier thermalization and exciton formation. Our results highlight the presence of coherent coupling between exciton and free carriers, particularly in the sub-100 femtosecond timescales.

This study introduces a novel techno-economic approach to renewable ammonia production using landfill biogas. The proposed process involves bio-hydrogen generation from landfill biogas, nitrogen production via air separation, and the Haber-Bosch process. Building on our prior research, which demonstrated the economic competitiveness of renewable hydrogen production from landfill gas, we extend our investigation to analyze the feasibility of producing renewable ammonia from biogas-derived bio-hydrogen. However, the economic analysis for the baseline scenario reveals the current lack of profitability (net present value of −18.3 M€), with ammonia prices needing to quadruple to achieve profitability. Major costs, including investment, maintenance, overhead expenses, and electricity, collectively account for over 70%, suggesting the potential efficacy of investment subsidies as a political tool. Only cases with subsidies exceeding 50% of total investment costs, under current ammonia market prices, would render the green ammonia route profitable. Our findings underscore the significant techno-economic challenges in realizing renewable ammonia production, emphasizing the need for innovation in process engineering and catalytic technologies to enable competitive and scalable green ammonia production.