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A Combined Experimental and Theoretical Insights into the Synergistic Effect of Cerium Doping and Oxygen Vacancies into BaZrO <sub/>3-δ</sub> Hollow Nanospheres for Efficient Photocatalytic Hydrogen Production
摘要： The long-standing debate over the influence of oxygen vacancies and various dopants has been the center point in perovskite-based compounds for their photocatalytic applications. Hydrothermally synthesized Cerium doped BaZrO3 (BZO) hollow nanospheres has been systematically studied by experimental and theoretical calculations to understand the effect of Cerium doping and oxygen vacancies on the photocatalytic properties. Compounds synthesized by a template-free route were composed of hollow nanospheres generated by Ostwald ripening of spherical nanospheres, which were formed by agglomeration of nanoparticles. The high alkaline condition and high temperature during the hydrothermal condition may lead to the formation of local disorders and oxygen vacancies in the compounds, confirmed by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) analysis and density functional theoretical (DFT) calculations. Combination of oxygen vacancies and progressive doping of Ce onto BZO, BaZr1–xCexO3 (x = 0.00 – 0.04), creates additional energy levels stipulated by vacancy defects and Ce mixed valance states within the band gap of BZO thereby reducing its band gap. The photocatalytic efficacy of the compounds has been examined by photo-driven H2 generation concomitant with oxidation of a sacrificial donor. In this study, BaZr0.97Ce0.03O3 shows the highest efficiency (823 μmol h-1 g-1) with an apparent quantum yield (AQY) of 6% in photocatalytic H2 production among all five synthesized samples. The data obtained from the UV–Vis DRS, XPS, ESR analysis and DFT calculations, the synergistic effect of decreasing the band gap due to Ce doping and the presence of Ce (III)/Ce (IV) pairs along with oxygen vacancies and lattice distortions could be the reasons behind the enhanced photocatalytic efficacy of BaZr1–xCexO3 (x = 0.00 – 0.04) under UV–Visible light.
关键词： Photocatalytic hydrogen production,Cerium doping,Oxygen vacancies,BaZrO3,Hollow nanospheres
更新于2025-11-21 11:01:37
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Snowflake-like Cu2S/Zn0.5Cd0.5S p–n heterojunction photocatalyst for enhanced visible light photocatalytic H2 evolution activity
摘要： Building a p–n heterojunction can accelerate the separation and transfer of photoinduced charges, which is considered to be a promising approach to constructing photocatalysts with excellent H2 evolution activities. Herein, novel snowflake-like Cu2S/Zn0.5Cd0.5S heterojunction photocatalysts were successfully synthesized. Compared to the pure Cu2S and Zn0.5Cd0.5S, the as-synthesized Cu2S/Zn0.5Cd0.5S showed remarkably improved H2 evolution rate. Cu2S/Zn0.5Cd0.5S with a Cu2S content of 3 wt% showed the optimized H2 evolution rate of 4923.5 μmol g?1 h?1 in Na2S–Na2SO3 solutions, and the corresponding apparent quantum efficiency is 30.2% at 420 nm. The experimental results indicate that the enhanced H2 evolution rates can be attributed to the fabrication of the p–n heterojunction between Cu2S and Zn0.5Cd0.5S, effectively boosting photogenerated charge carriers separation and transfer. Moreover, a plausible mechanism was proposed.
关键词： Photocatalytic,Hydrogen production,Snowflake-like,p–n heterojunction
更新于2025-09-23 15:23:52
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Revealing the role of kapok fibre as bio-template for In-situ construction of C-doped g-C3N4@C, N co-doped TiO2 core-shell heterojunction photocatalyst and its photocatalytic hydrogen production performance
摘要： For the first time, C-doped g-C3N4@C, N co-doped TiO2 core-shell heterojunction photocatalyst was successfully prepared by an in-situ one-pot hydrothermal bio-template approach, assisted by calcination treatment at 500?°C. Kapok fibre was used as a bio-templates and in-situ C doping in g-C3N4 and TiO2 during the formation of core-shell heterojunction photocatalyst. Moreover, the used of urea as g-C3N4-precursor also contribute to band-gap narrowing by an in-situ carbon and nitrogen doping in TiO2. Various characterisation techniques were employed to understand the effect TiO2 precursor concentration on the evolution of core-shell nanostructure heterojunction photocatalyst that can affect and boost the catalytic activity. The detailed understanding of the concurrent growth of C-doped g-C3N4 (CCN) and C, N co-doped TiO2 mechanism, as well as the formation of core-shell nanostructures heterojunction formation, are also proposed in this study. Our finding indicated that the bio-template core-shell nanostructure heterojunction photocatalysts showed a dramatic increase in photoinduced electron-hole separation efficiency as demonstrated by the photoelectrochemical and photoluminescence analyses. The enhancement in photogenerated charge carrier separation and narrower band gap resulted in superior photocatalytic activities with the highest rate of hydrogen production was recorded by CCN/T-1.5 sample (625.5 μmol h-1 g-1) in methanol aqueous solution. The well-developed interconnected heterojunction formation with appropriate CCN and TiO2 contents in core-shell nanoarchitectures system is a prime factor for the future design of a highly efficient visible-light-driven photocatalyst.
关键词： Bio-template,Heterojunction photocatalyst,Core-shell,Co-doping,Photocatalytic hydrogen production,Visible light
更新于2025-09-23 15:23:52
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Photocatalytic hydrogen production by biomimetic indium sulfide using Mimosa pudica leaves as template
摘要： Biomimetic sulfur-deficient indium sulfide (In2.77S4) was synthesized by a template-assisted hydrothermal method using leaves of Mimosa pudica as a template for the first time. The effect of this template in modifying the morphology of the semiconductor particles was determined by physicochemical characterization, revealing an increase in surface area, decrease in microsphere size and pore size and an increase in pore volume density in samples synthesized with the template. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of organic sulfur (S-O/S-C/S-H) and sulfur oxide species (eSO2, SO3^2-, SO4^2-) at the surface of the indium sulfide in samples synthesized with the template. Biomimetic indium sulfide also showed significant amounts of Fe introduced as a contaminant present on the Mimosa pudica leaves. The presence of these sulfur and iron species favors the photocatalytic activity for hydrogen production by their acting as a sacrificial reagent and promoting water oxidation on the surface of the templated particles, respectively. The photocatalytic hydrogen production rates over optimally-prepared biomimetic indium sulfide and indium sulfide synthesized without the organic template were 73 and 22 mmol g^-1 h^-1, respectively, indicating an improvement by a factor of three in the templated sample.
关键词： Photocatalytic hydrogen production,XPS analysis,In2.77S4,Template-assisted hydrothermal
更新于2025-09-23 15:23:52
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Introduction of Nitrogen Defects into a Graphitic Carbon Nitride Framework by Selenium Vapor Treatment for Enhanced Photocatalytic Hydrogen Production
摘要： Graphitic carbon nitride (g-C3N4) is a metal-free semiconductor photocatalyst that has attracted significant attention due to its promising application in photocatalytic hydrogen production. However, pristine g-C3N4 suffers from a high recombination rate of photo-generated charge carriers and also has a limited visible-light absorption range, resulting in low photocatalytic activity. Herein, we report on the preparation and testing of a g-C3N4 photocatalyst with tunable nitrogen defects that delivered improved photocatalytic activity. The nitrogen defects were gradually introduced into the g-C3N4 framework by a selenium vapor treatment of pure g-C3N4, which resulted in improved, stable catalytic activity for photocatalytic hydrogen production. Based on the experimental results and DFT calculations, we proposed that the enhanced photoactivity is attributed to the defect state (DS) formed by the nitrogen vacancy (VN) in the unit cell of g-C3N4 and a small widening of visible light absorption. This nitrogen-based photocatalyst with nitrogen deficiencies was found to deliver an average hydrogen generation rate of 1.16 mmolg-1h-1 at room temperature (25 oC), which was 3.4 times greater than pristine g-C3N4. This process of introducing nitrogen defects into the graphitic carbon provides a promising way for enhancing the photocatalytic activity of g-C3N4-based materials for hydrogen production.
关键词： nitrogen vacancies,photocatalytic hydrogen production,g-C3N4,bandgap
更新于2025-09-23 15:22:29
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Highly efficient white-LED-light-driven photocatalytic hydrogen production using highly crystalline ZnFe2O4/MoS2 nanocomposites
摘要： Designing efficient photocatalytic systems for hydrogen evolution is extremely important from the viewpoint of the energy crisis. Highly crystalline heterostructure catalysts have been established, considering their interface electric field effect and structural features, which can help improve their photocatalytic hydrogen-production activity. In this study, we fabricated a highly crystalline heterojunction consisting of ZnFe2O4 nanobricks anchored onto 2D molybdenum disulfide (MoS2) nanosheets (i.e., ZnFe2O4/MoS2) via a hydrothermal approach. The optimized ZnFe2O4/MoS2 photocatalyst, with a ZnFe2O4 content of 7.5 wt%, exhibited a high hydrogen-production rate of 142.1 mmol h?1 g?1, which was 10.3 times greater than that for the pristine ZnFe2O4 under identical conditions. The photoelectrochemical results revealed that the ZnFe2O4/MoS2 heterojunction considerably diminished the recombination of electrons and holes and promoted efficient charge transfer. Subsequently, the plausible Z-scheme mechanism for photocatalytic hydrogen production under white-LED light irradiation was discussed. Additionally, the influence of cocatalysts on the photocatalytic hydrogen evolution for the ZnFe2O4/MoS2 heterostructure was investigated. This work has demonstrated a simplified coupling of one-dimensional or zero-dimensional structures with 2D nanosheets for improving the photocatalytic hydrogen production activity as well as confirmed that MoS2 is a viable substitute for precious metal-free photocatalysis.
关键词： Photocatalytic hydrogen production,Layered materials,MoS2,Photocatalysts,Heterojunction
更新于2025-09-23 15:21:01
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Facile preparation of self-assembled MXene@Au@CdS nanocomposite with enhanced photocatalytic hydrogen production activity; è?a???è￡??o3?±3?¤??????????MXene@Au@CdS???????¤????????????????????°￠?′???§;
摘要： Photocatalytic hydrogen production is considered a promising approach to generating clean sustainable energy. However, the conventional co-catalyst (e.g., Pt) used in photocatalytic hydrogen production is high-cost and difficult to obtain. Here, we designed and prepared a ternary nanocomposite MXene@Au@CdS, which can be used in the field of efficient and excellent photocatalytic hydrogen production. The MXene@Au@CdS has a hydrogen production rate of 17,070.43 μmol g?1 h?1 (tested for 2 h), which is 1.85 times that of pure CdS nanomaterials. The improved hydrogen production performance of the MXene@Au@CdS is attributed to: (i) MXene provides more active adsorption sites and reaction centers for Au and CdS nanoparticles; (ii) the synergistic effect of Au’s strong surface plasmon resonance expands the optical response range of CdS. Therefore, this work solves the problem of the solid connection between the surface functional groups of photocatalyst, and achieves rapid interface charge transfer and long-term stability during the hydrogen production.
关键词： MXene,nanocomposite,photocatalytic hydrogen production
更新于2025-09-23 15:21:01
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Realizing Synergistic Effect of Electronic Modulation and Nanostructure Engineering over Graphitic Carbon Nitride for Highly Efficient Visible-Light H2 Production Coupled with Benzyl Alcohol Oxidation
摘要： Photocatalytic H2 production based on g-C3N4 faces enormous challenging issues including limited visible-light absorption, poor separation and transfer abilities of photo-generated electron-hole pairs. Herein, we realize the synergistic effect of nanostructure engineering and electronic modulation with a supramolecular assembly mediated synthesis of heteroatom doped g-C3N4 hierarchical mesoporous spheres. The favorable doping site and possible effect on electronic structure are disclosed by DFT calculation with supporting experimental analysis. Impressively, S-doped g-C3N4 delivers a 13.2 times higher H2 production rate than bulk g-C3N4 under visible-light. More importantly, as the dual functional photocatalyst for H2 production and selective oxidation of benzyl alcohol, it can exhibit outstanding activity with a H2/benzaldehyde production rate of 3.76/3.87 μmol h-1, respectively. This work not only provide a new rationale for photocatalytic performance enhancement, but also shed new light on the highly efficient utilization of solar energy by coupling H2 generation with value added chemical production.
关键词： graphitic carbon nitride,hierarchical mesoporous spheres,DFT calculation,benzyl alcohol oxidation,photocatalytic hydrogen production
更新于2025-09-23 15:19:57
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Charge transfer dynamics and catalytic performance of a covalently linked hybrid assembly comprising a functionalized cobalt tetraazamacrocyclic catalyst and CuInS <sub/>2</sub> /ZnS quantum dots for photochemical hydrogen production
摘要： Although the cobalt complex, [Co(CR)X2]+ (CR ? 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene), has been studied as a catalyst for electro- and photochemical H2 generation and CO2 reduction for more than thirty years, only the unfunctionalized one was used as a free catalyst in bulk solutions. Considering that the immobilization of functionalized molecular catalysts (MCs) on the surface of light harvesting materials through a stable covalent linkage was often an effective strategy to boost the activity of semiconductor/MC hybrid photocatalytic systems, we prepared the first anchoring group-functionalized [Co(CR)X2]+ complex (C1, X ? Br), which bears a (20,60-dicarboxypyridin-40-yl) group at position 15 of the macrocyclic ligand. The covalent attachment of C1 to the surface of CuInS2/ZnS (CISZ) core–shell quantum dots (QDs) afforded the C1@CISZ hybrid assembly. Comparative studies on the visible-light-induced H2 evolution performances of C1@CISZ and the non-bonded reference system comprising the unfunctionalized [Co(CR)Br2]+ complex (C2) and CISZ QDs (denoted as C2+CISZ) revealed that the photocatalytic activity of C1@CISZ was twice to thrice as high as that of C2+CISZ under the same conditions. Appealingly, the isolated C1@CISZ assembly was more stable than the C2+CISZ system in long-term photolysis. Moreover, photoluminescence (PL) and transient absorption (TA) spectroscopic studies demonstrated that covalent immobilization of C1 on the surface of CISZ QDs accelerated the electron transfer from QDs to the catalyst and meanwhile retarded the charge recombination process on the surface of QDs. The evidently improved charge separation efficiency resulted in the higher activity of the hybrid assembly C1@CISZ than that of C2+CISZ for photocatalytic hydrogen production.
关键词： photochemical H2 generation,cobalt complex,photocatalytic hydrogen production,CO2 reduction,charge transfer dynamics,CuInS2/ZnS quantum dots
更新于2025-09-16 10:30:52
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MoS <sub/>2</sub> Quantum Dots Modified Black Ti <sup>3+</sup> –TiO <sub/>2</sub> /g‐C <sub/>3</sub> N <sub/>4</sub> Hollow Nanosphere Heterojunction toward Photocatalytic Hydrogen Production Enhancement
摘要： The MoS2 quantum dots (QDs) modified black Ti3+–TiO2/g-C3N4 hollow nanosphere heterojunction is synthesized via the continuous chemical template deposition and sculpture–reduction processes. The results of structural characterizations imply that the Ti3+–TiO2/g-C3N4/MoS2 QDs hollow nanosphere heterojunction is prepared successfully. The photocatalytic hydrogen evolution reaction (HER) of the B-TiO2/g-C3N4/MoS2 QDs (≈1524.37 μmol g?1 h?1) exhibits an enhancement of ≈33 folds compared with the normal TiO2. Furthermore, the process of photocatalysis and the mechanism of photocatalytic HER enhancement are explored, which can be ascribed to the HER activity sites of MoS2 QDs, Ti3+/Ov ions in the Ti3+–TiO2, and hollow nanosphere heterojunction, which are proved by electrochemical measurements.
关键词： MoS2 quantum dots,photocatalytic hydrogen production,heterojunction,black Ti3+–TiO2
更新于2025-09-11 14:15:04