Materials For CO2 Reduction Research Articles

Voltammetric investigation on iron-(nickel-)sulfur surface under conditions for the emergence of life

Iron (II) sulfide minerals have gained attention in the last decades due to their relevance in hypotheses for the emergence of life on the early Earth around 4 billion years ago. In the submarine vent theory, it has been proposed that those minerals, especially mackinawite, had a key role in prebiotic processes. Those are estimated to be present in a natural electrochemical setting, analogous to a chemiosmotic one, formed in the interface between the early ocean and the interior of the alkaline hydrothermal systems, the early vent-ocean interface. To evaluate this and other hypotheses, voltammetric studies were performed to better understand the electrochemical behavior of minerals under conditions analogous to the vent-ocean interface. The preliminary results presented here indicate that, in the potential range estimated to exist in that interface, mackinawite can transition to other mineral phases and may posibly coexist with other minerals, resulting from its oxidation. This can create a local chemical diversity. In addition, it has been tested a protocol for Ni incorporation in mackinawite structure, resulting in a surface that showed an interesting behavior in the presence of CO2, although definitive experiments showed necessary for a deeper comprehension of that behavior. Overall, the results are consistent with previous results on electrocatalytical properties of Fe-Ni-S materials for CO2 reduction, and also could lead to the emergence of a protometabolism on early Earth.

Graphene‐based catalysts for electrochemical carbon dioxide reduction

AbstractElectrochemical carbon dioxide (CO2) reduction is considered to be an efficient strategy to produce usable fuels and overcome the concerns regarding global warming. For this purpose, an efficient, earth abundant, and a low cost catalyst has to be designed. It has been found that graphene‐based materials could be promising candidates for CO2 conversion because of their unique physical, mechanical, and electronic properties. In addition, the surface of graphene‐based materials can be modified by using different strategies, including doping, defect engineering, producing composite structures, and wrapping shapes. In this review, the fundamentals of electrochemical CO2 reduction and recent progress of graphene‐based catalysts are investigated. Furthermore, recent studies on graphene‐based materials for CO2 reduction are summarized.

A Novel Ag2O/Fe–TiO2 Photocatalyst for CO2 Conversion into Methane Under Visible Light

Modified TiO2 based nanomaterials have attained significant interest because of their unique morphology and excellent optical and photocatalytic properties. In this research, a very novel and highly efficient Ag2O/Fe–TiO2 porous structure was developed by simple hydrothermal method. The structural and morphological properties of the photocatalysts were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface areas of the samples were measured by Brunauer–Emmett–Teller theory (BET). The chemical composition and optical properties were investigated using X-ray photoelectron spectroscopy (XPS) and UV–visible spectroscopy. The optical absorption measurements show a clear red-shift in absorption edge of Fe–TiO2 after loading of Ag2O (Ag2O/Fe–TiO2 composite). Moreover, Ag2O varying ratio (0–15 at.%) has also enhanced the efficiency of Ag2O/Fe–TiO2 photocatalyst for CO2 conversion into methane under visible light illumination (λ ≥ 420 nm). The optimum ratio of Ag2O loading which exhibited maximum performance is 10 at.%. Moreover, the 10%Ag2O/Fe–TiO2 composite synthesized at 180 °C hydrothermal temperature showed an excellent increase in photocatalytic activity than other composites synthesized at 150 and 210 °C. This excellent performance of photocatalyst can be attributed to the highly porous petal-like structure of composite. Therefore, it is expected that the present study will be a good addition in literature for designing highly active photocatalytic materials for reduction of CO2 into useful hydrocarbons.