Carbon dioxide photoconversion driven by visible-light excitation of small carbon nanoparticles in various configurations

Recent Advances in Heterogeneous Photocatalytic CO2 Conversion to Solar Fuels

“…Nonmetal-based photocatalysts especially carbon, ,,− carbon nitride, ,− and silicon carbide are also hot photocatalysts for solar fuel production. In addition to the informative and specialized reviews on this issues, ,, many carbon-based photocatalysts such as carbon quantum dots (CQDs), graphene (G), and/or its oxides (GO) are still used as photocatalysts or its supports in the last 3 years. − For instance, it was reported that GO is an effective, low-cost photocatalyst for simultaneous CO 2 reduction and solar energy harvesting . By modulating the oxygenated functional groups, the CH 3 OH conversion rate can be achieved up to 0.172 μmol h –1 g cat –1 on GO under 300 W halogen lamp irradiation, much higher than that of TiO 2 .…”

“…Recently, carbon quantum dots (CQDs) with bright fluorescence emissions, were also researched as new water-soluble photocatalysts for CO 2 reduction because their excellent photoinduced redox properties resemble those found in conventional semiconductor nanostructures. , Bunker and Sun’s group has demonstrated that aqueous suspended bare CQDs can be excited with visible light to convert CO 2 into formic acid with the performance competitive to that of widely used semiconductor nanoparticles . The surface-doping of the CQDs with a metal can substantially improve the CO 2 reduction activity. , Moreover, Au-doped carbon dots show visible-light-driven CO 2 reduction to small organic acids, including acetic acid (for which the reduction requires many more electrons than that for formic acid) and, more interestingly, demonstrate significantly enhanced activity with higher CO 2 pressures over aqueous suspended photocatalysts …”

Carbon Dots: Bottom‐Up Syntheses, Properties, and Light‐Harvesting Applications

“…To p-down methods include laser ablation,d ischarge, and electrochemical oxidation, which generally require expensive equipment and harsh conditions for the exfoliation or oxidation of carbon powder or graphitic rods. [7] In contrast, CDs can be readily synthesized using facile bottom-up methods, including hydrothermalo r solvothermalc arbonization,a cid hydrolysis,a nd microwave pyrolysis, starting from abundant and low-cost organic precursors. [8] In particular,C Ds display excellent light absorption and carrier generationp roperties, which result in high photoluminescence (PL) as well as efficient charge transfer to/fromthe materials hybridized.…”

Alternative photocatalysts to TiO 2 for the photocatalytic reduction of CO 2

“…The photocatalytic activity of carbonaceous photocatalysts has been studied either in aqueous/organic suspensions or in gas-solid systems where the gaseous reaction mixture consisted of H 2 O and CO 2 . Aqueous suspensions of BiVO 4 /RGO (51.5 μmol ethanol/g * 10h), ZnO(10%wt)/RGO (263.1 μmol CΗ 3 OΗ /g * 3h) and solutions of Cs 2 Mo 6 Br i 8 Br a 6 /GO (1644 μmol CΗ 3 OΗ /g * 24h) in H 2 O/DMF exhibited the most enhanced activities among the GR based carbonaceous photocatalysts [139,145,[147][148][149][150]. Among the g-C 3 N 4 photocatalysts, the optimal photocatalytic activities were exhibited by aqueous suspensions of g-C 3 N 4 /r-P (295 μmol CΗ 4 /g * h) and S/g-C 3 N 4 (1.12 umol CΗ 3 OΗ /g * 3h) owing to its surface defects [155,157,[170][171][172][173].…”

“…Besides, owing to the high mobility of charged species and its increased specific surface area, GO enhances the photocatalytic activity synergistically [149]. The photocatalytic efficiency of aqueous suspensions of carbon nanoparticles, bare or bearing metals (such as Au) on their surface, which act as electron acceptors, was also evaluated [150]. CdS nanorods /RGO composites photocatalytically reduced CO 2 to CH 4 under visible light irradiation (2.51 μmol CH 4 g * h).…”