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Enhanced light harvesting and electron-hole separation for efficient photocatalytic hydrogen evolution over Cu7S4-enwrapped Cu2O nanocubes
摘要： P-type Cu2O is an advantageous photocatalyst as the appropriate bandgap structure and low-cost. However, poor photocatalytic and instability of such promising material is still a great challenge. Here the core-shell Cu7S4-coated Cu2O nanocubes (Cu2O/Cu7S4 NCs) were successfully synthesized by solution method coupled with anion exchange, integrated structure of Cu2O/Cu7S4 NCs exhibited apparent improved photocatalytic hydrogen evolution activity compared with Cu2O photocatalyst. Particularly, Cu2O/Cu7S4 NCs had a high hydrogen production rate of 1689.00 μmol·g-1·h-1 under full spectra irradiation with additives of Na2SO3, which was higher than that of Cu2O NCs with a factor of 1.71 times. Excellent synergistic effect of Cu2O and Cu7S4 can be responsible for the improved hydrogen evolution properties, namely, the presence of Cu7S4 with localized surface plasma resonance (LSPR) can promote the photogenerated electrons transfer from the Cu2O surface, prolong the photogenerated holes lifetime, accelerate the separation of photogenerated electrons and holes, and ameliorate the photoelectric properties of semiconductors. The in situ formed multifunctional Cu7S4 layer offers a promising avenue to design photocathodes rationally for photocatalytic water reduction.
关键词： Photocatalyst,Localized surface plasma resonance,Electron-hole separation,Hydrogen evolution reaction,Cu2O/Cu7S4 nanocubes
更新于2025-09-23 15:22:29
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Tuning electronic and optical properties of TiO<sub>2</sub> with Pt/Ag doping to a prospective photocatalyst: a first principles DFT study
摘要： Using first-principles density functional theory, the modulated electronic and optical properties of TiO2 with Pt/Ag substitutional dopants with varying concentration are investigated. Our calculations reveal the significant decreasing trend in the band gap of TiO2 while increasing the Pt (direct band gap) and Ag (indirect band gap) impurity concentration from 4.17% to 8.33% to 12.5%. The spin-polarized density of states reveal strong hybridization between the impurity bands with Ti-(3d) and O-(2p) bands near the Fermi level. The charge transfer mechanism depicts the delocalized electron cloud forming a strong bonding between the dopants (Pt/Ag) and oxygen of TiO2. Moreover, the absorption spectra of the Pt doped TiO2 structures have a broad peak at the visible range of energy spectrum with maximum absorption up to 0.7×10?5cm?1. The calculated reflectivity, energy loss function and extinction coefficient shows the enhanced optical properties of doped TiO2 compared to its pristine form. The obtained results predict the way to tailor the optical properties of Pt/Ag-doped TiO2 as an efficient photocatalyst in the visible region.
关键词： Pt,Optical properties,Electronic structure,Photocatalyst,Ag doped TiO2
更新于2025-09-23 15:22:29
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Effect of dissolved silica on photocatalytic water purification with a TiO2 ceramic catalyst
摘要： If photocatalytic water purification technologies will find practical applications, the impact of total dissolved solids in the source water on the activity of the photocatalyst must be evaluated. In this study, we evaluated the effects of SiO3 2? in water on a TiO2 ceramic photocatalyst; specifically, we determined the effects of SiO3 2? on the rate of photocatalytic degradation of formic acid (as a model contaminant) and on the rate of photocatalytic inactivation of Escherichia coli in an aqueous solution. Both the rate of formic acid degradation and the sterilization rate decreased with increasing SiO3 2? concentration. On the other hand, at a given SiO3 2? concentration, the activity of the photocatalyst did not decrease over the course of 120 h, and the surface structure of the photocatalyst did not change (i.e., no precipitate formed on the surface). The decreases in photocatalytic activity due to the presence of SiO3 2? could be recovered by flushing the experimental apparatus with distilled water. These results show that the reason for the lower photocatalytic activity in the presence of SiO3 2? than in its absence was due to adsorption of SiO3 2? onto the surface of the TiO2 photocatalyst and that SiO3 2? adsorption was an equilibrium process in water.
关键词： TiO2 ceramic photocatalyst,SiO3 2?,Photocatalysis,formic acid,E. coli
更新于2025-09-23 15:21:21
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Rational band design in metal chalcogenide Ba6Zn6HfS14: splitting orbitals, narrowing forbidden gap and boosting photocatalyst property
摘要： The insufficient light sources absorption often limits photocatalyst applications of metal chalcogenides because of their excessively broad band gap. Thus, it is necessary to discover and design a compound with rational band gap. Here, a new visible-light photocatalyst, Ba6Zn6HfS14, is prepared through the traditional high temperature solid-state reaction. A set of experiments on the visible-light decomposition of methylene blue demonstrated that the photocatalytic efficiency of Ba6Zn6HfS14 (0.00761 min-1) is improved, compared to that of Ba6Zn6ZrS14 (0.00553 min-1) which proved to be a previously reported visible-light photocatalyst with similar structure. The UV-visible reflection spectra demonstrated the energy gap of Ba6Zn6HfS14 (E1=1.45eV; E2 =2.55eV) is smaller than that of Ba6Zn6ZrS14 (E1 = 1.78eV; E2 = 2.50eV; E3 = 2.65eV). The Ba6Zn6HfS14 absorbs more visible light and exhibits preferably photocatalytic activity. The origin of splitted energy bands were elucidated via the first calculations.
关键词： band gap engineering,chalcogenides,visible-light photocatalyst
更新于2025-09-23 15:21:21
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Theory-Driven Heterojunction Photocatalyst Design with Continuously Adjustable Band Gap Materials
摘要： The utilization efficiency of hot carriers in photocatalyst is limited at present by their fast recombination. Heterojunction interface would reduce the recombination rate by effectively facilitating spatial separation of the hot electron and hole. Here, we establish a heterojunction photocatalyst design principle by using continuously adjustable band gap materials. This is demonstrated using first-principles calculations, and is subsequently validated by direct measurements of photocatalytic activity of ZnxCd1-xS-reduced graphene oxide (RGO) heterojunction as a proof-of-concept photocatalyst. Tuning the Zn/Cd ratio and/or the reduction degree of RGO can result into three types of heterojunction, and different conduction and valence band offsets by varying their band gap and positions of band edges. The modulation of efficient electron-hole separation at the interface is manifested by the consistency of calculated and experimental optical absorbance, and enhanced photocatalytical activity of ZnxCd1-xS-RGO heterojunction. This results can also rationalize the available experimental results of RGO-based composites. This design principle is broadly applicable to the development of other heterojunction materials ranging from photocatalysts and solar cells to functional electronic devices through interfacial band alignment engineering.
关键词： band gap,photocatalytic activity,RGO,heterojunction,ZnxCd1-xS,photocatalyst,first-principles calculations
更新于2025-09-23 15:21:21
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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Preparation and characterization of TiO2/BiVO4 composite: Can this photocatalyst, under visible light, be able to eliminate rhodamine B from water and why?
摘要： Bismuth vanadate (BiVO4) can be composited with titanium dioxide (TiO2) to obtain a photocatalyst that can be activated by visible light. Such photocatalyst may be operated by solar light, principally, a free photon source. Many researchers have been working hard to find a stable, efficient, and low cost photocatalytic systems. In this presentation, we will report our effort to prepare and characterize TiO2/BiVO4 composite, which is responsive under visible light. The TiO2/BiVO4 composite was prepared by co-precipitation method, in which the self-prepared TiO2 nanotubes was immersed in solution containing bismuth (III) and vanadate ions under certain pH. The freshly obtained TiO2/BiVO4 was dried and subjected to a heat treatment, then was characterized by XRD, UV-visible diffuse reflectance spectrophotometer, SEM, and photo-electro-chemical working station. The results showed a crystal phase mixture of TiO2/BiVO4 composite system, which are anatase (2θ of 27.5°, 36.1°, 54.3°) and monoclinic scheelite, bismuth vanadate (2θ of 19°, 29°). The photocurrent evolution under visible light exposure was investigated carefully. The results showed that the composite system is active under visible light, due to visible light absorption by narrow bandgap semiconductor, namely BiVO4. While the heterojunction system in TiO2/BiVO4 composite enhanced the separation of electron and charge, eventually, the electron would flow from the conduction band of BiVO4 to conduction band of TiO2, so the photocurrent will be enhanced. When this composite was being applied to the photoelectrocatalytic reactor system, containing aqueous rhodamine B, the enhancement of photo-catalytic degradation of rhodamine B was also significantly observed. The influence of bias potential applied during photoelectrocatalytic degradation process will be further discussed.
关键词： degradation rhodamine B,TiO2/BiVO4 composite,photocatalyst
更新于2025-09-23 15:21:21
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Hydrogen Production from Residual Glycerol in Biodiesel Synthesis by Photocatalytic Reforming
摘要： Biodiesel (BDF) has gained much attention as new sustainable energy alternative to petroleum-based fuels. In particular, BDF market has significantly increased in Europe to adhere energy and climate policies. Therefore, the increased BDF production requires new utilization of glycerol which is by product of BDF synthesis. We have focused on photocatalytic reforming using titanium oxide (TiO2) photocatalyst using glycerol as sacrificial agent (SaH). Recently we have found that SaH with all of the carbon attached oxygen atoms such as glycerol and methanol continued to serve as an electron source until their sacrificial ability was exhausted in photocatalyzed hydrogen evolution using a Pt-loaded TiO2 (Pt/TiO2) catalyst. Here we investigated the utilization of residual glycerol in BDF synthesis by photocatalytic reforming.
关键词： Bio-diesel,Reforming,TiO2,Hydrogen,Photocatalyst,BDF
更新于2025-09-23 15:21:21
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Bimetallic PtNi/g-C3N4 nanotubes with enhanced photocatalytic activity for H2 evolution under visible light irradiation
摘要： Bimetallic PtNi-decorated graphitic carbon nitride (g-C3N4) nanotubes were prepared through calcining the mixture of urea and thiourea in the presence of Pluronic F127, followed by deposition of bimetallic PtNi nanoparticles (NPs) via chemical reduction. It is found that the photocatalytic activity of PtNi/g-C3N4 nanotubes is strongly dependent on the molar ratio of Pt/Ni and the highest activity is observed for Pt1Ni1/g-C3N4. Under visible light (l > 420 nm) irradiation, the H2 generation rate over Pt1Ni1/g-C3N4 nanotubes is 104.7 mmol h?1 from a triethanolamine (10 vol%) aqueous solution, which is higher than that of Pt/g-C3N4 nanotubes (98.6 mmol h?1) and is about 47.6 times higher than that of pure g-C3N4 nanotubes. The cyclic photocatalytic reaction indicates that our Pt1Ni1/g-C3N4 nanotubes function as a stable photocatalyst for visible light-driven H2 production. The effect of bimetallic PtNi NPs in the transfer and separation of photogenerated charge carriers occurring in the excited g-C3N4 nanotubes was investigated by performing photoelectrochemical and photoluminescence measurements. Our results reveal that bimetallic PtNi could replace Pt as a promising cocatalyst for photocatalytic H2 evolution with better performance and lower cost.
关键词： Hydrogen evolution,g-C3N4,Nanotube,Bimetallic PtNi,Photocatalyst
更新于2025-09-23 15:21:21
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Room temperature synthesis of CdS/SrTiO3 nanodots-on-nanocubes for efficient photocatalytic H2 evolution from water
摘要： Spontaneous solar-driven water splitting to generate H2 with no pollution discharge is an ideal H2 generation approach. However, its ef?ciency remains far from real application owing to the poor light-harvesting and ultrafast charge recombination of photocatalysts. To address these issues, herein, we employed a novel but simple chemical bath deposition (CBD) method to construct CdS/SrTiO3 nanodots-on- nanocubes at room temperature (ca. 25 (cid:1)C). The as-synthesized nanohybrids not only expand light absorption from ultraviolet (UV) to visible light but also signi?cantly retard charge recombination owing to the well-de?ned heterostructure formation. As a result, the CdS/SrTiO3 exhibits high photocatalytic performance with H2 evolution rate of 1322 lmol g(cid:1)1 h(cid:1)1, which is 2.8 and 12.2 times higher than that of pristine CdS and SrTiO3, respectively. This work provides a universal approach for the heterostructure construction, and inspired by this, higher ef?cient photocatalysts for H2 evolution may be developed in the near future.
关键词： Nanoheterostructure,H2 generation,Room temperature,CdS/SrTiO3,Photocatalyst
更新于2025-09-23 15:21:21
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Cu2O photocatalyst modified antifouling polysulfone mixed matrix membrane for ultrafiltration of protein and visible light driven photocatalytic pharmaceutical removal
摘要： This study explains synthesis, characterization of an effective and efficient mixed matrix polysulfone (PSF) ultrafiltration membrane modified with Cu2O photocatalyst, synthesized using electrodeposition method, for pharmaceutical removal. Cu2O photocatalyst, polyethylene glycol, and N-methyl-2-pyrrolidone were used as additive, pore former, and solvent, respectively in the phase inversion method. Characterization techniques, such as XRD, FTIR, FESEM, FESEM-EDX, and AFM were used to characterize the photocatalyst and blended membranes so as to analyze their structural and functional attributes. Further, the membranes were analyzed by using permeation techniques to analyze their flux profiles. Similarly, antifouling nature and hydrophilicity of the membranes were studied by permeating aqueous BSA solutions and measuring the static water contact angle (SWCA), respectively. The pharmaceutical removal studies were carried out using ibuprofen (IBP). The additive improves the membrane attributes, such as flux improved from 34.24 L m-2 h-1 to 179.54 L m-2 h-1 deciphering improved porosity and pore size distribution; SWCA decreased from 71.5° to 45.3° showing increase in the hydrophilicity of the membranes; BSA adsorption decreased from 56 μg cm-2 to 27 μg cm-2; and successful removal of IBP at 86% was achieved under visible light conditions with a removal rate of 32.63 × 10-3 min-1.
关键词： antifouling,Ultrafiltration,mixed matrix membranes,pharmaceutical,Photocatalyst
更新于2025-09-23 15:21:21