Self-Assembled Synthesis of Porous Iron-Doped Graphitic Carbon Nitride Nanostructures for Efficient Photocatalytic Hydrogen Evolution and Nitrogen Fixation

Abstract

In this study, Fe-doped graphitic carbon nitride (Fe-MCNC) with varying Fe contents was synthesized via a supramolecular approach, followed by thermal exfoliation, and was then used for accelerated photocatalytic hydrogen evolution and nitrogen fixation. Various techniques were used to study the physicochemical properties of the MCN (g-C3N4 from melamine) and Fe-MCNC (MCN for g-C3N4 and C for cyanuric acid) catalysts. The field emission scanning electron microscopy (FE-SEM) images clearly demonstrate that the morphology of Fe-MCNC changes from planar sheets to porous, partially twisted (partially developed nanotube and nanorod) nanostructures. The elemental mapping study confirms the uniform distribution of Fe on the MCNC surface. The X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectroscopy (UV-DRS) results suggest that the Fe species might exist in the Fe3+ state and form Fe-N bonds with N atoms, thereby extending the visible light absorption areas and decreasing the band gap of MCN. Furthermore, doping with precise amounts of Fe might induce exfoliation and increase the specific surface area, but excessive Fe could destroy the MCN structure. The optimized Fe-MCNC nanostructure had a specific surface area of 23.6 m2 g−1, which was 8.1 times greater than that of MCN (2.89 m2 g−1). To study its photocatalytic properties, the nanostructure was tested for photocatalytic hydrogen evolution and nitrogen fixation; 2Fe-MCNC shows the highest photocatalytic activity, which is approximately 13.3 times and 2.4 times better, respectively, than MCN-1H. Due to its high efficiency and stability, the Fe-MCNC nanostructure is a promising and ideal photocatalyst for a wide range of applications.

Synergistic Enhancement of Water-Splitting Performance Using MOF-Derived Ceria-Modified g-C3N4 Nanocomposites: Synthesis, Performance Evaluation, and Stability Prediction with Machine Learning

“…Hence, such NCs having higher concentrations of defects can lead to heightened photocatalytic performance because such vacancies can act as donors as well as there can be an efficient production of photoinduced carrier pairs. 56,57 PEC Water Splitting. The current−voltage curves were established for bare g-C 3 N 4 , gC NCs, and ternary gC/metal oxide hybrid structurebased photoanodes in 0.5 M Na 2 SO 4 under light conditions.…”

“…This indicates that these synthesized samples have a higher concentration of defects than bare g-C 3 N 4 NSs. Hence, such NCs having higher concentrations of defects can lead to heightened photocatalytic performance because such vacancies can act as donors as well as there can be an efficient production of photoinduced carrier pairs. , …”

Recent Advances in Application of 1D Nanomaterials for Photocatalytic Nitrogen Fixation

“…If an organic solvent is used, then the process is termed solvothermal. Although some syntheses have been conducted under supercritical conditions, the vast majority of nanomaterial synthesis occurs at significantly lower temperatures and pressures [80][81][82]. This approach has been used to create a variety of essential nanomaterials with 1D morphologies, such as nanotubes, nanorods, and nanowires, including TiO 2 , ZnO, g-C 3 N 4 , and CdTe [80,[83][84][85].…”

“…Although some syntheses have been conducted under supercritical conditions, the vast majority of nanomaterial synthesis occurs at significantly lower temperatures and pressures [80][81][82]. This approach has been used to create a variety of essential nanomaterials with 1D morphologies, such as nanotubes, nanorods, and nanowires, including TiO 2 , ZnO, g-C 3 N 4 , and CdTe [80,[83][84][85]. The hydrothermal approach has been extensively used for synthesizing nanostructured titania, which is considered a highly significant photocatalyst.…”

Recent Advances on g‐C3N4 Based Photocatalysts for Typical Antibiotics Photodegradation: Preparation, Mechanism and Influencing Factors

“…[47] Doping can achieve catalysis in the visual region due to the impurity energy levels formed by the dopant ions that narrow the forbidden band of graphite-phase carbon nitride, and it is an effective way to modulate its electronic structure, which is widely used for high-efficiency transformation of the solar energy. [48] To date, elemental doping of g-C 3 N 4 includes metallic elements (e. g., iron (Fe), [49] copper (Cu), [50] cobalt (Co), [51] etc.) and non-metallic elements (e. g., nitrogen (N), [52] oxygen (O), [53] sulfur (S), [54] phosphorus (P), [55] etc.)…”