Shedding Light Onto the Nature of Iron Decorated Graphene and Graphite Oxide Nanohybrids for CO₂ Conversion at Atmospheric Pressure

Abstract

We report on the design and testing of new graphite and graphene oxide‐based extended π‐conjugated synthetic scaffolds for applications in sustainable chemistry transformations. Nanoparticle‐functionalised carbonaceous catalysts for new Fischer Tropsch and Reverse GasWater Shift (RGWS) transformations were prepared: functional graphene oxides emerged from graphite powders via an adapted Hummer's method and subsequently impregnated with uniform‐sized nanoparticles. Then the resulting nanomaterials were imaged by TEM, SEM, EDX, AFM and characterised by IR, XPS and Raman spectroscopies prior to incorporation of Pd(II) promoters and further microscopic and spectroscopic analysis. Newly synthesised 2D and 3D layered nanostructures incorporating carbon‐supported iron oxide nanoparticulate pre‐catalysts were tested, upon hydrogen reduction in situ, for the conversion of CO2 to CO as well as for the selective formation of CH4 and longer chain hydrocarbons. The reduction reaction was also carried out and the catalytic species isolated and fully characterised. The catalytic activity of a graphene oxide‐supported iron oxide pre‐catalyst converted CO2 into hydrocarbons at different temperatures (305, 335, 370 and 405 °C), and its activity compared well with that of the analogues supported on graphite oxide, the 3‐dimensional material precursor to the graphene oxide. Investigation into the use of graphene oxide as a framework for catalysis showed that it has promising activity with respect to reverse gas water shift (RWGS) reaction of CO2 to CO, even at the low levels of catalyst used and under the rather mild conditions employed at atmospheric pressure. Whilst the γ‐Fe2O3 decorated graphene oxide‐based pre‐catalyst displays fairly constant activity up to 405 °C, it was found by GC‐MS analysis to be unstable with respect to decomposition at higher temperatures. The addition of palladium as a promoter increased the activity of the iron functionalised graphite oxide in the RWGS. The activity of graphene oxide supported catalysts was found to be enhanced with respect to that of iron‐functionalised graphite oxide with, or without palladium as a promoter, and comparable to that of Fe@carbon nanotube‐based systems tested under analogous conditions. These results display a significant step forward for the catalytic activity estimations for the iron functionalised and rapidly processable and scalable graphene oxide. The hereby investigated phenomena are of particular relevance for the understanding of the intimate surface morphologies and the potential role of non‐covalent interactions in the iron oxide‐graphene oxide networks, which could inform the design of nano‐materials with performance in future sustainable catalysis applications.

The effect of thermally treated AlN powder on PVT-grown single crystals

“…Furthermore, while the FFT patterns of the AlN lattice are observed for both crystals A and B in Fig. 5, crystal A exhibits an additional pattern due to the presence of micro-sized graphite oxides, 23,24 which are not observed in crystal B. The assignment of the graphite oxide was determined by secondary phase with expanded lattice of crystal A.…”

Shedding light on the use of graphene oxide-thiosemicarbazone hybrids towards the rapid immobilisation of methylene blue and functional coumarins

“…From a large selection of micrographs corresponding to different batches of GO, ZnBTSC and ZnBTSC@GO complexes including several previously published batches, 57–59 the pore size of such hybrids was measured directly from SEM images using ImageJ 1.52. 60…”

“…From a large selection of micrographs corresponding to different batches of GO, ZnBTSC and ZnBTSC@GO complexes including several previously published batches, [57][58][59] the pore Fig. 4 Extensive FESEM imaging whereby solid samples were deposited on HOPG as the carbon support and gold coated, for various batches of (a) GO, (b) ZnBTSC3, (c) ZnBTSC4 and (d) ZnBTSC3@GO with corresponding estimated pore sizes distributions for (e) GO, (f) compound ZnBTSC3 and (g) compound ZnBTSC4 (h) ZnBTSC3@GO hybrid, showing a general trend for the diminishing of pore sizes of GO upon ZnBTSC3 incorporation.…”

“…The pore sizes estimated here are a very good match with previously reported values from BET measurements for GO, rGO and porphyrin-rGO systems. 57,58 Previous studies reporting solvothermal/hydrothermal fabricated graphene 3D structures generally led to a relatively large pore sizes of around 5 mm or above. [62][63][64][65][66] Considering the striking difference in the hybrid morphology for the morphology of compound ZnBTSC3 when supported onto GO with respect to individual components, it we postulated that the two species (ZnBTSC and GO nanoakes) that the species remain associated in the dispersed phase.…”

Self-Assembled Materials Incorporating Functional Porphyrins and Carbon Nanoplatforms as Building Blocks for Photovoltaic Energy Applications

“…We reported recently on the lab scale preparation of new functional porphyrins modified in both meso-and β-position and metalled to obtain a more tuneable UV-vis absorption. Such functional porphyrins have been deemed challenging to synthesis on a lab scale previously; however, in our recent studies, we isolated these and studied their interactions with carbon nanomaterials (Mao et al, 2016;Tyson et al, 2016a;Mao et al, 2017;Calatayud et al, 2019;Mao et al, 2019;Owen et al, 2020).…”