Sensitization of La modified NaTaO 3 with cobalt tetra phenyl porphyrin for photo catalytic reduction of CO 2 by water with UV–visible light

Photocatalytic CO2 Conversion to Ethanol: A Concise Review

Photo-catalytically converting the greenhouse gas CO2 into ethanol is an important avenue for the mitigation of climate issues and the utilization of renewable energies. Catalysts play critical roles in the reaction of photocatalytic CO2 conversion to ethanol, and a number of catalysts have been investigated, including semiconductors and plasmonic metal-based catalysts, as well as several other catalysts. In this review, the progress in the development of each category of catalysts is summarized, the current status is reviewed, the remaining challenges are pointed out, and the future research directions are prospected, with the aim being to pave pathways for the rational design of better catalysts.

Porphyrins and phthalocyanines as biomimetic tools for photocatalytic H2 production and CO2 reduction

The increasing energy demand and environmental issues caused by the over-exploitation of fossil fuels render the need for renewable, clean, and environmentally benign energy sources unquestionably urgent. The zero-emission energy carrier, H₂ is an ideal alternative to carbon-based fuels especially when it is generated photocatalytically from water. Additionally, the photocatalytic conversion of CO₂ into chemical fuels can reduce the CO₂ emissions and have a positive environmental and economic impact. Inspired by natural photosynthesis, plenty of artificial photocatalytic schemes based on porphyrinoids have been investigated. This review covers the recent advances in photocatalytic H₂ production and CO₂ reduction systems containing porphyrin or phthalocyanine derivatives. The unique properties of porphyrinoids enable their utilization both as chromophores and as catalysts. The homogeneous photocatalytic systems are initially described, presenting the various approaches for the improvement of photosensitizing activity and the enhancement of catalytic performance at the molecular level. On the other hand, for the development of the heterogeneous systems, numerous methods were employed such as self-assembled supramolecular porphyrinoid nanostructures, construction of organic frameworks, combination with 2D materials and adsorption onto semiconductors. The dye sensitization on semiconductors opened the way for molecular-based dye-sensitized photoelectrochemical cells (DSPECs) devices based on porphyrins and phthalocyanines. The research in photocatalytic systems as discussed herein remains challenging since there are still many limitations making them unfeasible to be used at a large scale application before finding a large-scale application.

Synthesis of SrTiO3 submicron cubes with simultaneous and competitive photocatalytic activity for H2O splitting and CO2 reduction

Single crystalline strontium titanate (SrTiO3) submicron cubes have been synthesized based on a molten salt method. The submicron cubes showed superior photocatalytic activity towards both water splitting and carbon dioxide reduction, in which methane (CH4) and hydrogen (H2) were simultaneously produced. The average production rate of methane up to 8 h is 4.39 μmol g-1 h-1 but drops to 0.46 μmol g-1 h-1. However, the average production rate of hydrogen is 14.52 before 8 h but then increases to 120.23 μmol g-1 h-1 after 8 h. The rate change of the two processes confirms the competition between the H2O splitting and CO2 reduction reactions. Band structure and surface characteristics of the SrTiO3 submicron cubes were characterized by diffuse reflective UV-Vis spectroscopy, Mott-Schottky analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results reveal that the simultaneous and competitive production of methane and hydrogen is due to a thermodynamics factor, as well as the competition between the adsorption of carbon dioxide and water molecules on the surface of the faceted SrTiO3. This work demonstrates that SrTiO3 photocatalysts are efficient in producing sustainable fuels via water splitting and carbon dioxide reduction reactions.

Nanostructured materials for photocatalysis

Photocatalysis is a green technology which converts abundantly available photonic energy into useful chemical energy.

A review on photocatalytic CO2 reduction using perovskite oxide nanomaterials

As the search for efficient catalysts for CO₂ photoreduction continues, nanostructured perovskite oxides have emerged as a class of high-performance photocatalytic materials. The perovskite oxide candidates for CO₂ photoreduction are primarily nanostructured forms of titanates, niobates, tantalates and cobaltates. These materials form the focus of this review article because they are much sought-after due to their nontoxic nature, adequate chemical stability, and tunable crystal structures, bandgaps and surface energies. As compared to conventional semiconductors and nanomaterial catalysts, nanostructured perovskite oxides also exhibit an extended optical-absorption edge, longer charge carrier lifetimes, and favorable band-alignment with respect to reduction potential of activated CO₂ and reduction products of the same. While CO₂ reduction product yields of several hundred μmol^-1 h^-1 are observed with many types of perovskite oxide nanomaterials in stand-alone forms, yield of such quantities are not common with semiconductor nanomaterials of other types. In this review, we present current state-of-the-art synthesis methods to form perovskite oxide nanomaterials, and procedures to engineer their bandgaps. This review also presents a comprehensive summary and discussion on crystal structures, defect distribution, morphologies and electronic properties of the perovskite oxides, and correlation of these properties to CO₂ photoreduction performance. This review offers researchers key insights for developing advanced perovskite oxides in order to further improve the yields of CO₂ reduction products.