We report herein the preparation and characterization of six readily assembled bis-coordinated homoleptic silver(I) N,N′-bis(arylimino)acenaphthene (BIAN) complexes of general structure [Ag(I)(BIAN)₂]BF₄ and the influence of the electronic properties of the ligand substitution pattern on their performance in electrochemical CO₂ reduction (CO₂R). All the explored catalysts displayed substantial current enhancements in carbon-dioxide-saturated solvents dependent on the ligated BIAN and no significant concurrent H₂ evolution when utilizing 2% H₂O as a proton source. Additionally, preliminary studies, employing a drop-casted ink of 0.4 mg cm⁻² [Ag(I)(4-OMe-BIAN)₂]BF₄ (Ag4) immobilized onto carbon paper gas diffusion electrodes in a flow cell with 1M KHCO₃ aqueous electrolyte, resulted in a propitious Faradaic efficiency of 51% for CO at a current density of 50 mA cm⁻².

In recent years, CO ₂ electrolysis, particularly the electrochemical reduction of CO ₂ to CO in zero‐gap systems, has gained significant attention. While Ag‐coated gas diffusion electrodes are commonly used in state‐of‐the‐art systems, heterogenized molecular catalysts like bis‐coordinated homoleptic silver(I) N,N‐bis(arylimino)‐acenaphthene (Ag‐BIAN) complexes are emerging as a promising alternative due to their tunability and high mass activity. In this study, the influence of ink composition on the performance of Ag‐BIAN‐based GDEs in zero‐gap electrolyzers (ZGEs) are systematically explored at 60 °C and 600 mA cm⁻ ² . Sedimentation analyses across various solvents informed the selection of optimal solvent‐catalyst and solvent‐carbon additive combinations, streamlining the GDE optimization process and reducing associated costs and time. These results demonstrate that solvent choice and dilution state of the ink are critical factors impacting CO ₂ reduction, achieving faradaic efficiencies for CO production (FE _CO ) up to 67% at 600 mA cm⁻ ² with catalyst loadings as low as 0.2 mg cm⁻ ² . These findings lay the groundwork for advancing from homogeneous H‐type cells to industrial ZGE systems through tailored ink engineering.

We report on the manufacture of a state-of-the-art heterogeneous non-noble metal catalyst, which is based on a molecularly well-defined phosphine-tagged cobalt corrole complex. This precursor compound is readily synthesized from convenient starting materials while the active material is obtained through wet-impregnation of the pertinent metalliferous macrocycle onto carbon black followed by controlled pyrolysis of the loaded carrier material under an inert gas atmosphere. Thus, the obtained composite was then applied in the heterogeneous hydrogenation of various nitroarenes to yield a vast array of valuable aniline derivatives that were conveniently isolated as their hydrochloride salts. The introduced catalytic protocol is robust and user-friendly with the entire assembly of the reaction set-up enabling the conduction of the experiments on the laboratory bench without any protection from air.

In this study, we propose a practical approach for producing a heterobimetallic Ni(II)-Ce(III) diimine complex from an extended salen-type ligand (H₂L) to serve as an electrocatalyst for CO₂ reduction and demonstrate an outstanding overall efficiency of 99.6% of the cerium-nickel complex and integrate it into applicable cell assemblies. We optimize not only the catalyst, but the operational conditions enabling successful CO₂ electrolysis over extended periods at different current densities. A comparison of electrochemical behavior in H-cell and zero-gap cell electrolyzers suggests potential applications for industrial scale-up. In the H-cell electrolyzer configuration, the most elevated efficiency in CO production was achieved with a selectivity of 56.96% at -1.01 V vs RHE, while HCOO^- formation exhibited a selectivity of 32.24% at -1.11 V vs RHE. The highest TON was determined to be 14657.0 for CO formation, followed by HCOO^- with a TON of 927.8 at -1.11 V vs RHE. In the zero-gap electrolyzer configuration, the most efficient setup toward CO production was identified at a current density (CD) of 75 mA cm^-2, a flow rate of 10 mL min^-1, operating at 60 °C and utilizing a low KOH concentration of 0.1 M to yield a maximum faradaic efficiency (FE_CO) of 82.1% during 24 h of stable electrocatalysis.

Redox-active ligands offer powerful opportunities to modulate catalytic reactivity while minimizing precious metal loading. Herein, we report the mechanochemical synthesis and comprehensive characterization of homoleptic silver(I) bis(arylimino)acenaphthene (Ag–BIAN) complexes and their application in homogeneous and heterogeneous zero-gap CO2 electroreduction. The molecular catalysts exhibit pronounced ligand-centered redox activity, with two reversible reductions assigned to sequential BIAN-based electron uptake. Under a CO2 atmosphere, significant catalytic current enhancement is observed between the first and second ligand-centered reductions, consistent with activation of electrogenerated reduced species. In a zero-gap electrolyzer configuration, the Ag–BIAN complexes achieve Faradaic efficiencies for CO formation of 70–90% at current densities up to 300 mA cm–2. Notably, the tailored molecular design enables a tenfold reduction in silver loading compared to Ag nanoparticle benchmarks while maintaining high catalytic performance. The material cost of the catalysts amounts to only €7.5–9.8 g–1, substantially improving economic feasibility. These findings demonstrate that redox-active ligand frameworks can decouple catalytic activity from metal mass loading and provide a viable molecular alternative to heterogeneous silver systems for efficient CO2-to-CO conversion.