Conversion of carbon dioxide to methanol: A comprehensive review

This review explains the various methods of conversion of Carbon dioxide (CO₂) to methanol by using homogenous, heterogeneous catalysts through hydrogenation, photochemical, electrochemical, and photo-electrochemical techniques. Since, CO₂ is the major contributor to global warming, its utilization for the production of fuels and chemicals is one of the best ways to save our environment in a sustainable manner. However, as the CO₂ is very stable and less reactive, a proper method and catalyst development is most important to break the CO₂ bond to produce valuable chemicals like methanol. Litertaure says the catalyt types, ratio and it surface structure along with the temperature and pressure are the most controlling parameters to optimize the process for the production of methanol from CO₂. This article explains about the various controlling parameters of synthesis of Methanol from CO₂ along with the advantages and drawbacks of each process. The mechanism of each synthesis process in presence of metal supported catalyst is described. Basically the activity of Cu supported catalyst and its stability based on the activity for the methanol synthesis from CO₂ through various methods is critically described.

Carbon-dot wrapped ZnO nanoparticle-based photoelectrochemical sensor for selective monitoring of H2O2 released from cancer cells

This study reports on a simple approach for the fabrication of an electrode modified with biocompatible C-dot wrapped ZnO nanoparticles for selective photoelectrochemical monitoring of H₂O₂ released from living cells. The biocompatibility of the ZnO nanoparticles was confirmed through in-vitro cellular testing using the MTT assay on Huh7 cell lines. The ZnO nanoparticles wrapped with dopamine-derived C-dots possess numerous catalytically active sites, excessive surface defects, good electrical conductivity, and efficient separation ability of photo-induced electrons and holes. These properties offer highly sensitive and selective non-enzymatic photo-electrochemical monitoring of H₂O₂ released from HeLa cells after stimulation with N-formylmethionyl-leucyl-phenylalanine. The sensor has a wide linear range (20-800 nM), low detection limit (2.4 nM), and reliable reproducibility, this implying its suitability for biological and biomedical applications. Graphical abstract Schematic of the fabrication of ZnO nanoparticles by using a plant extract as a reducing agent. Wrapping of ZnO with C-dots enhances the photoelectrocatalytic efficacy. Sensitive and selective photoelectrochemical monitoring of H₂O₂ released from cancer cells is demonstrated.

Structural and compositional control in copper selenide nanocrystals for light-induced self-repairable electrodes

In nature, self-healing can be induced by sunlight for damage and wound repair, and this phenomenon is very important to living species for prolonging their lives. This self-repairing feature is obviously highly desirable for non-biological materials and manmade systems. In this paper, we demonstrate, for the first time, that battery electrodes can be self-repaired when exposed to sunlight. Here, we show that the optical, and photoelectrochemical (PEC) properties can be controlled by varying structural and compositional parameters of copper selenide nanocrystals (NCs). Cation to anion ratio in copper selenide (Cu_2±xSe) NCs can be controlled over a wide range of 1.3-2.7 by simply changing the reaction temperature and impurity. Light-induced self-repairable behavior is demonstrated with electrochemical (EC) and PEC performances of electrodes made with stoichiometric copper selenide NCs. This nature-inspired, self-repairing behavior can be applied to batteries, supercapacitors, and photo-electrochemical fuel generators.

Enhanced TiO2 nanorods photocatalysts with partially reduced graphene oxide for degrading aqueous hazardous pollutants

Enhanced TiO₂ nanorods (TNRs) with partially reduced graphene oxide (RGO) (designated as GT) were prepared for degrading aqueous hazardous pollutants. The degree of RGO oxidation had an important role in affecting the photoelectronic and photocatalytic activities of GT composites. The study examined the impact of the degree of RGO oxidation on the photocatalytic activities. The photocatalytic activity of the materials was investigated for degrading rhodamine b (RhB), methyl orange (MO), methylene blue (MB), and phenol by using ultraviolet (UV) light. The highest photocatalytic activity was observed when the atomic oxygen-to-carbon (O/C) ratio of RGO was 0.130 ± 0.003. This study suggested the photocatalytic performance was maximized by preserving a selected amount of the RGO oxygen-containing groups. The work reported in this study on optimizing the RGO-based TiO₂ photocatalyst could serve as a promising approach for preparing and optimizing other types of carbon-based photocatalysts such as graphene-based CdS.