RESUMEN
The electroreduction of carbon dioxide (eCO2RR) to CO using Ag nanoparticles as an electrocatalyst is promising as an industrial carbon capture and utilization (CCU) technique to mitigate CO2 emissions. Nevertheless, the long-term stability of these Ag nanoparticles has been insufficient despite initial high Faradaic efficiencies and/or partial current densities. To improve the stability, we evaluated an up-scalable and easily tunable synthesis route to deposit low-weight percentages of Ag nanoparticles (NPs) on and into the framework of a nitrogen-doped ordered mesoporous carbon (NOMC) structure. By exploiting this so-called nanoparticle confinement strategy, the nanoparticle mobility under operation is strongly reduced. As a result, particle detachment and agglomeration, two of the most pronounced electrocatalytic degradation mechanisms, are (partially) blocked and catalyst durability is improved. Several synthesis parameters, such as the anchoring agent, the weight percentage of Ag NPs, and the type of carbonaceous support material, were modified in a controlled manner to evaluate their respective impact on the overall electrochemical performance, with a strong emphasis on operational stability. The resulting powders were evaluated through electrochemical and physicochemical characterization methods, including X-ray diffraction (XRD), N2-physisorption, Inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), SEM-energy-dispersive X-ray spectroscopy (SEM-EDS), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), STEM-EDS, electron tomography, and X-ray photoelectron spectroscopy (XPS). The optimized Ag/soft-NOMC catalysts showed both a promising selectivity (â¼80%) and stability compared with commercial Ag NPs while decreasing the loading of the transition metal by more than 50%. The stability of both the 5 and 10 wt % Ag/soft-NOMC catalysts showed considerable improvements by anchoring the Ag NPs on and into a NOMC framework, resulting in a 267% improvement in CO selectivity after 72 h (despite initial losses) compared to commercial Ag NPs. These results demonstrate the promising strategy of anchoring Ag NPs to improve the CO selectivity during prolonged experiments due to the reduced mobility of the Ag NPs and thus enhanced stability.
RESUMEN
This is the first time that the pore-space-partition (PSP) strategy is being successfully applied in the electrochemical field for water splitting, realizing the highly efficient construction of a series of ultrastable pristine MOF electrocatalysts. On integrating the vanadium-based trimetallic building cluster (M2V), the target M2V-MOFs exhibit excellent electrocatalytic activity for HER, OER, and water splitting. In particular, ultralow overpotentials of 314 and 198 mV for Fe2V-MOF as OER and HER electrocatalysts, respectively, can drive a current density of 10 mA cm-2. The fabricated Fe2V-MOF||Pt/C two-electrode configuration for the overall water splitting yields a current density of 10 mA cm-2 at only 1.6 V vs RHE, which is superior to that of the commercial IrO2||Pt/C couple. Notably, high structural and chemical stabilities still can be observed in alkaline condition. This work opens up an exciting pathway to design efficient and stable electrocatalysts based on pristine MOF by integrating the PSP strategy and multimetallic centers.