Graphitic Carbon Nitride with Dopant Induced Charge Localization for Enhanced Photoreduction of CO₂ to CH₄

Abstract

The photoreduction of CO2 to hydrocarbon products has attracted much attention because it provides an avenue to directly synthesize value‐added carbon‐based fuels and feedstocks using solar energy. Among various photocatalysts, graphitic carbon nitride (g‐C3N4) has emerged as an attractive metal‐free visible‐light photocatalyst due to its advantages of earth‐abundance, nontoxicity, and stability. Unfortunately, its photocatalytic efficiency is seriously limited by charge carriers′ ready recombination and their low reaction dynamics. Modifying the local electronic structure of g‐C3N4 is predicted to be an efficient way to improve the charge transfer and reaction efficiency. Here, boron (B) is doped into the large cavity between adjacent tri‐s‐triazine units via coordination with two‐coordinated N atoms. Theoretical calculations prove that the new electron excitation from N (2px, 2py) to B (2px, 2py) with the same orbital direction in B‐doped g‐C3N4 is much easier than N (2px, 2py) to C 2pz in pure g‐C3N4, and improves the charge transfer and localization, and thus the reaction dynamics. Moreover, B atoms doping changes the adsorption of CO (intermediate), and can act as active sites for CH4 production. As a result, the optimal sample of 1%B/g‐C3N4 exhibits better selectivity for CH4 with ≈32 times higher yield than that of pure g‐C3N4.

Iron phthalocyanine with coordination induced electronic localization to boost oxygen reduction reaction

“…It should be mentioned that FeAB-O exhibits a lower peak intensity of in-plane FeN 4 structure than that of FePc/AB, which can be attributed to the axial coordination breaking the in-plane Fe-N 4 structure 17,39 . Additionally, extended X-ray absorption fine structure (EXAFS) spectra of Fe K-edge show that the coordination number of Fe in FeAB-O is higher than the precise four nitrogen-coordination (FeN 4 ) and lower than the six-oxygen coordination (FeO 6 ) in Fe 2 O 3 , respectively 40,41 . These characterization results prove the formation of axial O coordination between the FePc and oxygen group of AB-O in FeAB-O.…”

Designing a 0D/2D S‐Scheme Heterojunction over Polymeric Carbon Nitride for Visible‐Light Photocatalytic Inactivation of Bacteria

“…Thei nsitu irradiated XPS spectroscopy acts as one of effective tools to investigate the chemical state of elements and flow direction of electrons.A ss hown in Figure 6, all the XPS spectra have been calibrated with reference to C1 peak at 284.6 eV before analysis.F or the high-resolution XPS spectra of Ce lements in Figure 6a,t he peaks at 284.6 and 286.4 eV are mainly attributed to the surface adventitious carbon species C À C/C = Cand C À O, respectively.T he peak at 287.9 eV on the PCN framework can be assigned to the N = C À N 2 . [30] In comparison with pristine PCN,t his peak over the CeO 2 /PCN composite shifts to higher binding energy (288.1 eV) in darkness and lower binding energy (287.7 eV) under illumination, which suggests that the Cspecies of PCN component in CeO 2 /PCN composite are the electron donor in the absence of illumination but electron acceptor under illumination. Thes imilar phenomenon occurs in the highresolution XPS spectra of Ne lements in Figure 6b.F or pristine PCN,t he peaks at 401.2, 399.7, and 398.3 eV are related to the amino Na toms (N À H), bridging Na toms (N À (C) 3 ), and sp 2 -hybridized Na toms (C = N À C), respectively.…”

Designing a 0D/2D S‐Scheme Heterojunction over Polymeric Carbon Nitride for Visible‐Light Photocatalytic Inactivation of Bacteria

“…For the high‐resolution XPS spectra of C elements in Figure a, the peaks at 284.6 and 286.4 eV are mainly attributed to the surface adventitious carbon species C−C/C=C and C−O, respectively. The peak at 287.9 eV on the PCN framework can be assigned to the N=C−N 2 . In comparison with pristine PCN, this peak over the CeO 2 /PCN composite shifts to higher binding energy (288.1 eV) in darkness and lower binding energy (287.7 eV) under illumination, which suggests that the C species of PCN component in CeO 2 /PCN composite are the electron donor in the absence of illumination but electron acceptor under illumination.…”