Supercritical Carbon Dioxide-Based Processes in Photocatalytic Applications

Abstract

Conventional methods generally used to synthesize heterogeneous photocatalysts have some drawbacks, mainly the difficult control/preservation of catalysts’ morphology, size or structure, which strongly affect the photocatalytic activity. Supercritical carbon dioxide (scCO2)-assisted techniques have recently been shown to be a promising approach to overcome these limitations, which are still a challenge. In addition, compared to traditional methods, these innovative techniques permit the synthesis of high-performance photocatalysts by reducing the use of toxic and polluting solvents and, consequently, the environmental impact of long-term catalyst preparation. Specifically, the versatility of scCO2 allows to prepare catalysts with different structures (e.g., nanoparticles or metal-loaded supports) by several supercritical processes for the photocatalytic degradation of various compounds. This is the first updated review on the use of scCO2-assisted techniques for photocatalytic applications. We hope this review provides useful information on different approaches and future perspectives.

Porous Aerogels and Adsorption of Pollutants from Water and Air: A Review

“…As mentioned before, SAs have unique properties that have made them attractive in many areas [ 159 ]. For example, they can be used (1) as absorbents of oils and organic liquids, to control accidental and deliberate releases of these substances during transportation and storage [ 160 ]; (2) as humidity sensors and matrices for biosensors [ 161 ]; (3) in thermal and acoustic insulation [ 162 , 163 ]; (4) as catalysts, photocatalysts, or catalyst carriers [ 164 , 165 ]; (5) as sorbents to capture CO 2 gas [ 166 ]; (6) in the removal of air pollutants—such as benzene, toluene, ethylbenzene, and xylene (BTEX) [ 167 ]—or, in general, of volatile organic compounds (VOCs) [ 168 ]; or (7) in wastewater treatments, such as in the removal of dyes [ 169 ], or of heavy metal ions [ 170 ].…”

Supercritical CO2 Directional‐Assisted Synthesis of Low‐Dimensional Materials for Functional Applications

“…Motivated by the thrill of these discoveries, there have been significant advances in supercritical fluid-facilitated exfoliation and processing, ranging from fundamental science and applied technologies. [109][110][111][112] For example, an ultrasonic-assisted production of graphene in SC CO 2 using a pressure reactor coupled with an ultrasonic generator can achieve a high yield of graphene sheets with less than three layers. [113] Moreover, a procedure of shear-assisted SC CO 2 exfoliation also the production of produce high-quality and large-quantity graphene nanosheets.…”

Study on supercritical CO2‐assisted modification of aramid pulp and properties of its reinforced EPDM composites

“…At present, many metal organic compounds, hydrocarbons, esters, ethers, and epoxy compounds have been soluble in scCO 2 ; thus, scCO 2 has been widely used in the synthesis and deposition of nanomaterials. [29][30][31] The precursor can be uniformly dispersed into the matrix to synthesize the non-agglomerated nanomaterial in scCO 2 . In our previous research, under the scCO 2 environment, nano-SiO 2 and nano-TiO 2 were synthesized uniformly on the surface of the aramid fiber without agglomeration, thereby improving the high-temperature resistance, mechanical properties, and UV resistance of the aramid fiber.…”