Frustrated Lewis Pairs Constructed on 2D Amorphous Carbon Nitride for High‐Selective Photocatalytic CO₂ Reduction to CH₄

Abstract

Photocatalytic reduction of CO2 into high value‐added fuels paves a new avenue for alleviating the energy crisis and green‐house effect, yet it is still challenging to achieve a highly active photocatalyst with high selectivity. Herein, for the first time, a facile structural engineering strategy is developed to construct tunable frustrated Lewis pairs (FLPs) on 2D amorphous graphitic carbon nitride (C3N4) via the introduction of boric acid with the assistance of supercritical CO2, wherein the FLPs are composed of B(OH)2 groups (Lewis acid sites) and adjacent NHx (Lewis base sites). Ideally, the synergetic effects of the FLPs on the 2D amorphous C3N4 can help to efficiently adsorb, activate, and reduce CO2 to CH4 with enhanced selectivity of ≈96.0%.

Strong ferromagnetism of g-C3N4 achieved by atomic manipulation

“…To fabricate the borate-functionalized 2D amorphous g-C 3 N 4 nanosheets (B-C 3 N 4 -X MPa), wherein B refers to the introduced boron bridges and X refers to the pressure of SC CO 2 , one-step SC CO 2 treatment was utilized, where H 3 BO 3 is used as the boron source. In this process, the straining and anisotropic acidic etching effect of SC CO 2 is expected to cleave the weak van der Waals forces between layers and the in-planar hydrogen bonds of tri-s-triazine units in the layers, thereby exfoliating bulk C 3 N 4 into 2D nanosheets, facilitating the formation of the amorphous and defective structure with -NH x groups [26][27][28][29][30] . Meanwhile, since H 3 BO 3 is presented over the preparation process, the empty sp 2 orbital on B of H 3 BO 3 is expected to be nucleophilic attacked by the lone pair of -NH x groups of the defected g-C 3 N 4 26 , forming in-planar bridging -B(OH)-groups (Fig.…”

“…1a, b). Specifically, the introduction of planar B into the g-C 3 N 4 motif is accomplished by supercritical CO 2 treatment, which has been well demonstrated in heteroatom doping [24][25][26] . To our knowledge, introducing bridging B to establish the exchange of local magnetic moments and form long-range magnetic order, tuning magnetic property of 2D materials is proposed for the first time.…”

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

“…Considering the phase transition in crystal structure relying on pressure and temperature, strain engineering of SC CO 2 plays a key role in the morphology evolution, lattice distortion, and destruction of 2D materials. [ 151–159 ] Through altering the pressure and temperature, single‐layer 2D VS 2 nanosheets have been successfully obtained in SC CO 2 expanded solvent systems (such as water/SC CO 2 /NMP). [ 160 ] The experiment results showed that the similar surface energies of NMP and VS 2 , the enhanced solubility and diffusivity of VS 2 , and anisotropic etching are critical factors in the exfoliation efficiency.…”

“…Considering the phase transition in crystal structure relying on pressure and temperature, strain engineering of SC CO 2 plays a key role in the morphology evolution, lattice distortion, and destruction of 2D materials. [151][152][153][154][155][156][157][158][159] Through altering [143] Copyright 2021, Wiley-VCH.…”

Constructing a crystalline–amorphous hydrated niobium pentoxide homojunction for superior photocatalytic CO2 reduction into CH4 with high selectivity

“…29 Particularly, selective production of CH 4 from CO 2 photoreduction was witnessed by constructing an amorphous phase on crystalline photocatalysts such as titania (TiO 2 ) and graphitic carbon nitride (g-C 3 N 4 ). 30,31 Therefore, the construction of a crystalline-amorphous homojunction in semiconductor photocatalysts is a promising approach to boost the photoactivity and selectivity of CO 2 reduction. Nonetheless, the fabrication of a crystalline-amorphous interface in photocatalysts usually involves complex synthesis procedures, such as acid treatment on the catalyst surface or thermal treatment under H 2 -rich conditions at high temperature.…”