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Enhanced Charge Separation in g-C3N4 – BiOI Heterostructures for Visible Light Driven Photoelectrochemical Water Splitting
摘要： Heterojunctions of the low bandgap semiconductor bismuth oxyiodide (BiOI) with bulk multilayered graphitic carbon nitride (g-C3N4) and few layered graphitic carbon nitride sheets (g-C3N4-S) are synthesized and investigated as an active photoanode material for sunlight driven water splitting. HR-TEM and elemental mapping reveals formation of a unique heterostructure between BiOI platelets and the carbon nitride (g-C3N4 and g-C3N4-S) network that consisted of dendritic BiOI nanoplates surrounded by g-C3N4 sheets. The presence of BiOI in g-C3N4-S/BiOI and g-C3N4-S/BiOI nanocomposites extends the visible light absorption profile from 500 nm up to 650 nm. Due to excellent charge separation in g-C3N4/BiOI and g-C3N4-S/BiOI, evident from quenching of the carbon nitride photoluminescence (PL) and a decrease in the PL lifetime, a significant increase in photoelectrochemical performance is observed for both types of g-C3N4-BiOI heterojunctions. In comparison to heterojunctions of bulk g-C3N4 with BiOI, the nancomposite consisting of few layered sheets of g-C3N4 and BiOI exhibits higher photocurrent density due to lower recombination in few layered sheets. A synergistic trap passivation and charge separation is found to occur in the g-C3N4-S/BiOI nanocomposite heterostructure which results in a higher photocurrent and a lower charge transfer resistance.
关键词： visible light driven photocatalysis,earth abundant semiconductor heterostructures,Graphenic semiconductors,photoelectrochemistry
更新于2025-11-21 11:01:37
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Cyano-rich mesoporous carbon nitride nanospheres for visible-light-driven photocatalytic degradation of pollutants
摘要： Visible-light-responsive photocatalysis offers exciting opportunities for sustainable environmental pollution control, but the unsatisfactory photoactivity of the existing photocatalysts impedes their practical application. Here, we fabricated a high-activity mesoporous carbon nitride nanosphere (MCNS) photocatalyst by a hard template synthesis method through incomplete polycondensation of the cyanamide precursors during thermal polymerization. The MCNS showed a unique nanosphere structure with a larger specific surface area and possessed more abundant cyano groups than two other graphitic carbon nitride (g-C3N4) materials (i.e., nanosheet and bulk g-C3N4). Experimental results and theoretical calculations indicate important roles of the cyano groups in narrowing the catalyst band gap to favor visible light absorption and accelerating the separation of the electron–hole pairs. With such superior surface properties and improved charge separation efficiency, the MCNS exhibited 14.7 times higher photocatalytic activity for bisphenol A (BPA) degradation than the bulk g-C3N4. The MCNS also showed good stability during repeated use. Therefore, the as-prepared MCNS has great potential for visible-light-responsive photocatalysis in environmental remediation and other photocatalytic applications.
关键词： pollutant degradation,visible-light-driven photocatalysis,bisphenol A,environmental remediation,Cyano-rich mesoporous carbon nitride nanospheres
更新于2025-09-19 17:15:36
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Surface plasma Ag-decorated single-crystalline TiO2?x(B) nanorod/defect-rich g-C3N4 nanosheet ternary superstructure 3D heterojunctions as enhanced visible-light-driven photocatalyst
摘要： Ag-TiO2-x(B)/g-C3N4 ternary heterojunctions photocatalysts are fabricated by hydrothermal-calcination, photo-deposition procedure, and followed by in-situ solid-state chemical reduction procedure. As-obtained photocatalysts are consisted with heterojunctions between 2D g-C3N4 sheets and 1D TiO2(B) single-crystalline nanorods. The band gap of Ag-TiO2-x(B)/g-C3N4 ternary heterojunctions photocatalysts is reduced to ~2.23 eV due to plasma Ag and surface engineering. Under visible light irradiation, it has an optimal photocatalytic property for the reduction of Cr6+ (95%) and degradation of NH4+ (93%). The apparent reaction rate constants (k) of ternary heterojunctions photocatalysts for NH4+ and Cr6+ are 25 and 12 folds higher than that of original TiO2(B). Furthermore, Ag-TiO2-x(B)/g-C3N4 also has excellent hydrogen production efficiency, which is up to 410 mmol h-1 g-1. This enhancement can be attributed to the unique heterojunction formed by 1D single-crystalline TiO2(B) nanorods and 2D g-C3N4 sheets, surface plasma resonance effect of plasma Ag nanoparticle, and surface engineering. A possible photocatalytic mechanism is also proposed by analysizing the XPS valence-band spectra and the Mott-Schottky.
关键词： Surface engineering,g-C3N4 sheet,Visible-light-driven photocatalysis,Single-crystalline TiO2(B) nanorod,Heterojunction
更新于2025-09-19 17:15:36
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Visible-light-driven Photocatalytic Removal of PPCPs using Magnetically Separable Bismuth Oxybromo-iodide Solid Solutions: Mechanisms, Pathways, and Reusability in Real Sewage
摘要： In testing a series of bismuth oxybromo-iodide (BiOBrxI1-x; 0 ≤ x ≤ 1) solid solutions, BiOBr0.9I0.1, due to its superior charge-carriers separation, exhibited the best performance in the visible-light-driven photocatalytic degradation of pharmaceutical and personal care products (PPCPs). Subsequently, its superparamagnetic version, BiOBr0.9I0.1/Fe3O4@SiO2, possessing a mesoporous hierarchical morphology, was solvothermally developed, and completely degraded the two model PPCPs, ibuprofen and benzophenone-3, in 1 and 2 h, respectively. Scavenger studies revealed that the ibuprofen degradation was dominated by e–, ?O2–, and h+, while the benzophenone-3 degradation was dominated by e– and ?O2–. Hydroxylation, decarboxylation, and demethylation were found to be the major reactions involved in the degradation pathways. The aquatic toxicity of the intermediates ― estimated using the ECOSAR software ― was found to be lower than for the parent PPCP molecules, indicating a reduced environmental risk after photocatalytic degradation. The solution matrix study elaborated the varying extent of the interacting roles of the co-present anions, cations, and NOM. The reusability and stability of BiOBr0.9I0.1/Fe3O4@SiO2 was examined in real secondary treated sewage in a prototype photocatalytic reactor equipped with a magnetic separator. Due to the interferences and unwanted interactions caused by the co-present constituents in secondary treated sewage, a gradual loss in the photocatalytic performance of BiOBr0.9I0.1/Fe3O4@SiO2 was observed during consecutive rounds of recycling.
关键词： visible-light-driven photocatalysis,magnetic photocatalyst,Bismuth oxyhalide,pharmaceuticals and personal care products,solid solution
更新于2025-09-19 17:15:36
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Tripyridine-Derivatives-Derived Semiconducting Iodo-argentate/cuprate Hybrids with Excellent Visible-light Induced Photocatalytic Performance
摘要： Through regulating the pH values, a series of iodo-argentate/cuprate hybrids, [Me3(4-TPT)]4[Ag6I18] (1, Me3(4-TPT) = N,N’,N’’-trimethyl-2,4,6-tris(4-pyridyl)-1,3,5-triazine), [Me3(4-TPT)][M5I8] (M=Ag/2, Cu/2a), [Me3(3-TPT)][M5I8] (Me3(3-TPT) = N,N’,N’’-trimethyl-2,4,6-tris(3-pyridyl)-1,3,5-triazine, M=Ag/3, Cu/4), exhibit adjustable structural variations with different dimensional structures, have been obtained under solvothermal conditions. They are directed by two types of in situ N-alkylation TPT-derivatives (Me3(4-TPT) for 1/2/2a and Me3(3-TPT) for 3/4) and represent the isolated units (1), 1-D polymeric chain (4), 2-D layered structures (2/2a, 3) based on diverse metal iodide clusters. These compounds possess reducing band gaps comparing with the bulk β-AgI and CuI and belong to potential semiconductor materials. Iodocuprates feature highly efficient photocatalytic activity in sunlight-induced degradation of organic dyes. The detailed study on the possible photocatalytic mechanism, including the radical trapping tests and theoretical calculations, reveals that the N-alkylation TPT moieties contribute to the narrow semiconducting behavior and effectively inhibit the recombination of photogenerated electron–hole pairs, which result in an excellent visible-light induced photocatalytic performance.
关键词： visible-light-driven,photocatalysis,structural variations,inorganic–organic hybrid metal halides,polypyridine-derivatives
更新于2025-09-09 09:28:46
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Selective Ferroelectric BiOI/Bi4Ti3O12 Heterostructures For Visible-light-driven Photocatalysis
摘要： Ferroelectric-photocatalyst/photocatalyst heterojunctions have very attractive photocatalytic activities. Beside enhanced charge carrier separation due to their internal electric fields, charge transfer could be even further enhanced by designing the heterojunction interface. In this work, the polarization-adsorption interaction that exists in ferroelectric materials was employed for successful deposition of BiOI on specific surfaces of Bi4Ti3O12 plates in the dark at room temperature, where the positively polarized region was found. The crystal structure, morphology, and composition of samples were confirmed by X-ray diffraction, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. Higher photocatalytic activity was achieved by the use of heterojunctions, with the reason behind the enhancement of activity confirmed to be the modified band structure, which contributed to the transfer of photoelectrons from Bi4Ti3O12 to BiOI, the increased visible light absorption, the increased active site area of positively polarized Bi4Ti3O12, and the elimination of the screening layer, which contributes impedance in charge transfer.
关键词： Visible-light-driven,Photocatalysis,Heterostructures,BiOI/Bi4Ti3O12,Ferroelectric
更新于2025-09-04 15:30:14