Recent Progress in the Photocatalytic Reduction of Carbon Dioxide

Abstract

Elimination or reduction of CO 2 in the atmosphere is a serious problem faced by humankind, and it has become imperative for chemists to find ways of transforming undesirable CO 2 to useful chemicals. One of the best means is the use of solar energy for the photochemical reduction of CO 2 . In spite of considerable efforts, discovery of stable photocatalysts which work in the absence of scavengers has remained a challenge although encouraging results have been obtained in the photocatalytic reduction of CO 2 in both gas and liquid phases. Semiconductor-based catalysts, multicomponent semiconductors, metal–organic frameworks (MOFs), and dyes as well as composites involving novel composite materials containing C 3 N 4 and MoS 2 have been employed for the photoreduction process. Semiconductor heterostructures, especially those containing bimetallic alloys as well as chemical modification of oxides and other materials with aliovalent anion substitution (N 3– and F – in place of O 2– ), remain worthwhile efforts. In this article, we provide a brief perspective of the present status of photocatalytic reduction of CO 2 in both liquid and gas phases.

Black TiO2: What are exact functions of disorder layer

“…In detail, hydrogen production reaction and CO 2 conversion reaction compete together at the same catalyst surface because the standard reduction potential of CO 2 into C 1 products is closely located at the reduction potential of water (Figure 4A). 60 Moreover, the negative energy level of the standard reduction potentials of CO 2 makes it harder to chose appropriate photocatalyst materials. Among the limited candidates for photocatalytic CO 2 reduction, TiO 2 is known as the best photocatalyst for CO 2 reduction because of its large bandgap energy with highly negative energy levels of CBM, long charge carrier lifetime, and fast water oxidation kinetics 57,61 .…”

Materials and Mechanisms of Photo‐Assisted Chemical Reactions under Light and Dark Conditions: Can Day–Night Photocatalysis Be Achieved?

“…Upon excitation,h oles will be transported to the p-type semiconductor for oxidative storage, in whiche lectrical neutrality will be maintained by the intercalation of anions or deintercalation of cations; thus the oxidative energy will be maintained stably.I nt he second model,a no xidanti s photocatalytically produced through the oxidation reactionand it oxidizes the redox-active material. (4)] are combined with the holes in TiO 2 .O nt he other hand, it is also possible that the photoexcited electrons in TiO 2 are consumed by an electron acceptor,s uch as active oxygen species( COH,H 2 O 2 ,O 2 C À /HO 2 C)a nd leading to the formation of oxidative species, as given in Equations (5) and (6). The electrons from Ni(OH) 2 [Eq.…”

“…[1,2] Of various strategies to address these concerns,p hotoassisted catalytic processes play vital roles. [3][4][5] It is not an exaggerationt os tate that photoassisted chemical reactions are ap romising phenomenon that could be employedf or severala pplications, such as environmental cleaningt hrough degradation of various pollutants, production of hydrogen through the watersplitting process, and fuel conversion. [6][7][8] In this context,m aterials are the key factorst om anifest the required phenomenon to successfully achievet he target applications.I nb rief, the phenomenon of photoassisted chemical reactions involves the absorption of light and the separation of excitons to produce potentialredox speciestoperform the reduction and oxidation reactions.…”

Experimental parameters affecting the photocatalytic reduction performance of CO2to methanol: A review

“…The addition of a hole scavenger, which is an independent, controllable experimental parameter, controls the density of holes present in the aqueous solution. Kamat noted the importance of scavenging one type of charge carrier, so as to make surplus the opposite charge type and allow it to accumulate within the photocatalyst particles.…”