Constructing van der Waals Heterogeneous Photocatalysts Based on Atomically Thin Carbon Nitride Sheets and Graphdiyne for Highly Efficient Photocatalytic Conversion of CO₂ into CO

Abstract

Atomically thin two-dimensional (2D) carbon nitride sheets (CNs) are attracting attention in the field of photocatalytic CO2 reduction. Because of the rapid recombination of photogenerated electron–hole pairs and limited more active sites, the photocatalytic efficiency of CNs cannot meet the actual requirements. Here, atomically thin 2D/2D van der Waals heterostructures of metal-free graphdiyne (GDY)/CNs are fabricated through a simple electrostatic self-assembly method. Experimental characterizations along with first-principles calculations show that the introduction of GDY in CNs promoted the transport of photogenerated carriers in the melon chain, thus suppressing the recombination of photogenerated electron–hole pairs. Both in situ FTIR measurements and DFT calculation confirm that the introduced GDY served as the CO2 adsorption site and enhanced the CO2 adsorption capacity of the CNs/GDY heterostructure. Thanks to the 2D/2D van der Waals heterojunction, the optimized CNs/GDY enhances significantly the CO generation rate up to 95.8 μmol g–1 that is 19.2-fold higher than that of CNs. This work provides a viable approach for the design of metal-free van der Waals heterostructure-based photocatalysts with high catalytic activity.

2D graphdiyne: an emerging carbon material

“…In recent years, GDY-based heterostructures have provided promising application potential in CO 2 reduction. [164][165][166][167][168][169][170] Gu et al 171 reported a 2D GDY/graphene (GDY/G) heterostructure to anchor cobalt phthalocyanine (CoPc) (Fig. 20a-d).…”

Constructing Heterogeneous Photocatalysts Based on Carbon Nitride Nanosheets and Graphene Quantum Dots for Highly Efficient Photocatalytic Hydrogen Generation

“…As a non-metallic photocatalyst, the atomically thin graphitic carbon-nitride nanosheets (CNs) are considered to be promising emerging photocatalysts because of their simple synthesis, high stability, and nontoxicity [ 6 , 24 , 27 , 28 ]. Although their conduction band and valence band position meet the requirements for overall water splitting, they can only respond to light of a wavelength below 419 nm owing to the large band gap of 3.06 eV, and therefore miss the most visible light [ 6 , 27 , 33 , 34 , 35 ]. Additionally, low photogenerated carrier separation efficiency and the quick recombination of photoinduced electron–hole pairs are still the key obstacles restricting the application of CNs.…”

“…To address these challenges, a composite of semiconductor photocatalytic materials and graphene systems can be used to broaden the absorption range of visible light and enhance the light absorption intensity of its materials [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. Due to graphene’s metallic properties, the heterojunctions constructed are transformed into Schottky heterojunctions.…”

Biotemplated g-C3N4/Au Periodic Hierarchical Structures for the Enhancement of Photocatalytic CO2 Reduction with Localized Surface Plasmon Resonance

“…284.9, 286.3, and 287.9/287.8 eV, corresponding to the C−C bonds of the graphitic carbon in the carbon nitride matrix or of the surface-contaminated carbon species, 35 C−NH 2 species, and sp 2 N−CN bonds in N-containing aromatic rings. 36 For the N 1s spectra (Figure 3b), four peaks at 398.3, 399.9, 400.9, and 404.0 eV are fitted in the CN−B spectrum, corresponding to the sp 2 -hybridized N-containing aromatic ring (C−NC), sp 3 -bonded N (N− [C] 3 ), amino-functional groups with a hydrogen atom (C−N− H), and π excitations from positive charge localization in the heterocycles. 37 It can be seen that the N 1s peak moves toward higher binding energy in the 10AuCN−B spectrum, which may mean that there is a significant flow of charge from g-C 3 N 4 to Au.…”

“…With the rapid improvement of the consumption level and industrial level in the human society, carbon-containing fossil fuels have been extensively developed and utilized. This phenomenon has caused a series of serious consequences, especially the rapid reduction of nonrenewable energy and the greenhouse effect caused by carbon dioxide (CO 2 ) emissions. , As widely recognized, solar energy is a kind of inexhaustible clean energy that has the potential to replace the fossil fuels, so collecting and converting solar energy to different kinds of chemical fuels attract widespread attention. − Among various technologies aiming to solve these problems mentioned above, such as electrochemical routes, thermochemical processes, and biomass production, the solar-driven photocatalytic CO 2 reduction reaction (CO 2 RR) is a promising strategy not only because it uses solar light as the sole energy source, but also because it converts CO 2 into renewable fuels such as carbon monoxide (CO) and hydrocarbons (CH 4 , C 2 H 4 , C 2 H 6 , etc.) .…”