Catalysts by pyrolysis: Direct observation of transformations during re-pyrolysis of transition metal-nitrogen-carbon materials leading to state-of-the-art platinum group metal-free electrocatalyst

Highly Durable and Selective Fe- and Mo-Based Atomically Dispersed Electrocatalysts for Nitrate Reduction to Ammonia via Distinct and Synergized NO2– Pathways

“…The atomically dispersed mono- and bimetallic catalysts in this work were synthesized using the well-established sacrificial support method (SSM). , The SSM class of M–N–C catalysts has been widely studied due to their good activity and stability for the oxygen reduction reaction (ORR), , where the oxidative cathodic potentials (0.6–1 V) are even harsher for carbon corrosion as compared to the reductive potentials in NO 3 RR (−0.8 to −0.2 V). The outstanding ORR performance for the SSM M–N–C was largely attributed to its high degree of graphitization and robust M–N x sites, which also greatly contributed to the excellent stability of the FeMo–N–C for NO 3 RR in this work (Figure a).…”

“…64,65 The SSM class of M− N−C catalysts has been widely studied due to their good activity and stability for the oxygen reduction reaction (ORR), 66,67 where the oxidative cathodic potentials (0.6−1 V) are even harsher for carbon corrosion as compared to the reductive potentials in NO 3 RR (−0.8 to −0.2 V). The outstanding ORR performance for the SSM M−N−C was largely attributed to its high degree of graphitization and robust M−N x sites, 68 which also greatly contributed to the excellent stability of the FeMo−N−C for NO 3 RR in this work (Figure 3a). Specifically, ICP-MS results showed a metal loading of 0.73 wt % for Fe−N−C and 1.36 wt % for Mo−N−C, while the bimetallic FeMo−N−C preserved 0.38 wt % Fe and 0.77 wt % Mo, as shown in Table S2.…”

Synergistic Electrocatalytic Syngas Production from Carbon Dioxide by Bi‐Metallic Atomically Dispersed Catalysts

“…The precursor mixture was then pyrolyzed in a reductive 7 % H 2 atmosphere, followed by a hydrofluoric acid wash which removed the silica template and metalic nanoparticles. A second pyrolysis under a reductive 10 % NH 3 atmosphere was performed which removes any fluorinated species, increases the graphitization content, etches micropores, and thereby enhances the catalytic activity [19] . The synthesis temperature was adjusted for the bi‐metallic FeMo−N−C samples to preserve atomically dispersed metallic sites.…”

“…A second pyrolysis under a reductive 10 % NH 3 atmosphere was performed which removes any fluorinated species, increases the graphitization content, etches micropores, and thereby enhances the catalytic activity. [19] The synthesis temperature was adjusted for the bi-metallic FeMoÀ NÀ C samples to preserve atomically dispersed metallic sites. Atomically dispersed MÀ N x active sites provide for the highest atom use efficiency and allow for a selectivity study without the influence from a separate metallic phase.…”

Understanding Synthesis–Structure–Performance Correlations of Nanoarchitectured Activated Carbons for Electrochemical Applications and Carbon Capture

“…To paint the textural/morphological/chemical variation of porosity, surface, and microcrystals during real operation, profound in situ or operando characterization is recommended to demonstrate the real-time reaction process of activated carbon materials. [499][500][501][502] For instance, operando XRD is employed to characterize the continuous revolution of lattice spacing, in situ Raman spectroscopy is proven to monitor the change in defect concentration clearly, and in situ infrared spectroscopy (FTIR) can observe the surface evolution under real conditions. In addition, by employing several techniques in materials informatics, such as sparse modeling and artificial neural networks, high-throughput peak detection and image analysis can be performed.…”