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Highly Enhanced Photocatalytic Water-splitting Activity of Gallium Zinc Oxynitride Derived from Flux-assisted Zn/Ga Layered Double Hydroxides
摘要： The Ga/Zn-oxynitride solid solution [(GaN)1-x(ZnO)x] is one of the promising visible-light harvesting photocatalysts for overall water-splitting. A series of (GaN)1-x(ZnO)x (0.11 ≤ x ≤ 0.33) are synthesized by calcining the carbonate-type Zn/Ga-LDH precursor with and without sodium carbonate flux at 850 oC for 8 - 14 h under a NH3 gas-flow. The solid solutions without flux are determined to be low in crystallinity but plate-like in morphology with preferred orientation could be observed. On the other hand, those with flux turn out to be better in crystallinity, and eventually exhibit significantly higher photocatalytic activity for overall water splitting under visible-light irradiation than those without flux. In addition, the bandgap energies can also be engineered from 2.57 eV to 2.72 eV by changing the synthetic parameter such as nitridation time. It is, therefore, suggested that the present new approach can offer new opportunities for designing the next generation photocatalytic systems.
关键词： Overall water splitting,Photocatalyst,Gallium Zinc Oxynitride,Layered double hydroxides,Flux
更新于2025-09-23 15:21:21
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A Noble-Metal-Free Heterogeneous Photosensitizer-Relay-Catalyst Triad Catalyzes Water Oxidation under Visible Light
摘要： An entirely earth abundant chromophore-relay-water oxidation catalyst triad system, which is robust and efficient at neutral pH, is presented. The synthesis involves the coordination of a porphyrin derivative to a bridging Fe(CN)5 group, which is then reacted with Co ions to prepare a covalently linked chromophore-Prussian blue analogue assembly. Light driven water oxidation studies in the presence of an electron scavenger indicate that the triad is active and it maintains a steady activity for at least 3 hours. Transient absorption experiments and computational studies reveal that the Fe(CN)5 group is more than a linker as it takes part in electron-transfer and co-operates with porphyrin in the charge separation process.
关键词： water splitting,triad,dye-sensitized,water oxidation,Prussian blue,porphyrin
更新于2025-09-23 15:21:01
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Ultrasound assisted deposition of highly stable self-assembled Bi2MoO6 nanoplates with selective crystal facet engineering as photoanode
摘要： The use of crystal facets of photocatalysts is well known as a promising strategy for the design of new photocatalysts with interesting physicochemical features for energy production applications. In this work, Bi2MoO6 thin films were synthesized by two methods, electrodeposition and sonoelectrodeposition. Preferential growth orientation depended on synthesis method. Results suggested that sonoelectrodeposition led to dominate the crystal facet {1 0 0} growth with self-assembled nanoplate morphologies while growth orientation in the {0 1 0} facet was dominant in electrodeposition in the absence of ultrasonic waves. As a highlight result, the {1 0 0} facet shows a smaller band gap, higher photocatalytic water splitting than the {0 1 0} facet. Efficient separation of charge pairs and long life time of photogenerated electrons was observed to be intrinsic features of the {1 0 0} facets. The higher charge transfer was confirmed by a higher photocurrent from linear sweep voltammetry and a smaller Nyquist radius arc. Ultrasound plays a key role in growth orientation and led to a production of homogeneous films with nanoplates which self-assembled together to form a flower-like structure. While in the absence of ultrasound the film has coral-like structure. Highly stable sonoelectrodeposited films exhibited incident photon-to-electron conversion efficiency (IPCE) of 22.4% at the specific wavelength of 500 nm. The sonoelectrodeposition method could act as a promising method for forming new films with specific crystal facet selection and developing as highly efficient photoanodes for PEC water splitting.
关键词： Crystal facet engineering,Coral-like,Water splitting,Bismuth molybdate,Self-assembled nanoplates,Sonoelectrodeposition
更新于2025-09-23 15:21:01
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Graphite/rolled graphene oxide/carbon nanotube photoelectrode for water splitting of exhaust car solution
摘要： Graphite/rolled graphene oxide/carbon nanotubes (G/R-GO/CNTs) was prepared and applied as a photoanode for water splitting from exhaust car solution. R-GO was prepared from graphene oxide (GO) using the modified Hummer method after settle down in solution for 2 months to roll out. The R-GO coated the graphite (G) electrode using the dip-coating method to form G/R-GO. Finally, CNTs were prepared on the G/R-GO electrode by using the chemical vapor deposition method to form G/R-GO/CNT electrode. The images of field emission scanning electron microscope show the formation of relatively homogenous and uniform R-GO with an average diameter of about 140 nm. Also, the high density of CNTs was observed with uniform diameters distribution and lengths of CNTs up to several micrometers. The values of the current density of the G/R-GO/CNT electrode for water splitting are changed from 0.82 mA cm?2 in dark to 1.50 mA cm?2 in light. The value of incident photon-to-current efficiency was 8.4% at 470 nm. The thermodynamic parameters were calculated, in which the activation energy (Ea), enthalpy (ΔH*), and entropy (ΔS*) values were 8.1 kJ mol?1, 29.9 J mol?1, and 56.4 J K?1 mol?1, respectively.
关键词： rolled graphene oxide,carbon nanotube,exhaust cars solution,H2 generation,water splitting
更新于2025-09-23 15:21:01
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Angstrom Thick ZnO Passivation Layer to Improve the Photoelectrochemical Water Splitting Performance of a TiO2 Nanowire Photoanode: The Role of Deposition Temperature
摘要： In this paper, we demonstrate that angstrom thick single atomic layer deposited (ALD) ZnO passivation can significantly improve the photoelectrochemical (PEC) activity of hydrothermally grown TiO2 NWs. It is found that this ultrathin ZnO coating can passivate the TiO2 surface defect states without hampering the carrier’s transfer dynamics. Moreover, a substantial improvement can be acquired by changing the deposition temperature of the ZnO layer (80 °C, and 250 °C) and named as 80 °C TiO2-ZnO, and 250 °C TiO2-ZnO. It was found that the deposition of this single layer in lower temperatures can lead to higher PEC activity compared to that deposited in higher ones. As a result of our PEC characterizations, it is proved that photoconversion efficiency of bare TiO2 NWs can be improved by a factor of 1.5 upon coating it with a single ZnO layer at 80 °C. Moreover, considering the fact that this layer is a passivating coating rather than a continuous layer, it also keeps the PEC stability of the design while this feature cannot be obtained in a thick shell layer case. This paper proposes a bottom up approach to control the electron transfer dynamics in a heterojunction design and it can be applied to other metal oxide combinations.
关键词： deposition temperature,atomic layer deposition,photoelectrochemical water splitting,ZnO passivation,TiO2 nanowire
更新于2025-09-23 15:21:01
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Nitrogen-doped Graphene Quantum Dots for Remarkable Solar Hydrogen Production
摘要： We synthesized nitrogen (N)-doped graphene quantum dots (N-GQDs) using a top-down hydrothermal cutting approach. The concentration of N dopants was readily controlled by adjusting the concentration of the N source of urea. When N dopants were incorporated into GQDs, visible absorption was induced by C-N bonds, which created another pathway for generating photoluminescence (PL). Time-resolved PL data revealed that the carrier lifetime of GQDs was increased upon doping with the optimized N concentration. The photoelectrochemical properties of N-GQDs towards water splitting were studied, and the results showed that 2N-GQDs prepared with 2 g of urea produced the highest photocurrent. The photocatalytic activity of 2N-GQDs powder photocatalyst for hydrogen production was also examined under AM 1.5G illumination, showing substantial enhancement over that of pristine GQDs. Electrochemical impedance spectroscopy data further revealed a significant improvement in charge dynamics and reaction kinetics, and an increased carrier concentration as a result of N doping.
关键词： Solar Hydrogen Production,Charge Dynamics,Water Splitting,Graphene Quantum Dots,Nitrogen-doped
更新于2025-09-23 15:21:01
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Enhanced Photoelectrochemical Water Oxidation from CdTe Photoanodes Annealed with CdCl2
摘要： CdTe absorbs sunlight up to 830 nm and has the potential to promote efficient photoelectrochemical (PEC) water splitting. However, most CdTe photoanodes and CdTe photocathodes show positive and negative photocurrent onset potentials for water oxidation and reduction, respectively, and are thus unable to drive PEC water splitting without external applied biases. In this work, we enhanced the activity of a CdTe photoanode having an internal p-n junction during PEC water oxidation by applying a CdCl2 annealing treatment together with surface modifications. The resulting CdTe photoanode generated photocurrents of 1.8 and 5.4 mA cm-2 at 0.6 and 1.2 VRHE, respectively, with a photoanodic current onset potential of 0.22 VRHE under simulated sunlight (AM 1.5G). The CdCl2 annealing increased the grain sizes in this material and lowered the density of grain boundaries, allowing for more efficient charge separation. Consequently, a two-electrode tandem PEC cell comprising a CdTe-based photoanode and photocathode split water without any external bias at a solar-to-hydrogen conversion efficiency of 0.51% at the beginning of the reaction.
关键词： Photoanode,Overall water splitting,Photoelectrochemistry,p-n junction,CdCl2 treatment
更新于2025-09-23 15:21:01
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Puffing quaternary FexCoyNi1-x-yP nanoarray via kinetically controlled alkaline etching for robust overall water splitting; ?￠±???è???3??????oè?¨???FexCoyNi1a??xa??yP??????é?μ?????????é?? ???è￡?è§￡?°′??§è??;
摘要： Designing and constructing bifunctional electrocatalysts with high efficiency, high stability and low cost for overall water splitting to produce clean hydrogen fuel is attractive but highly challenging. Here we constructed puffed quaternary FexCoyNi1?x?yP nanoarrays as bifunctional electrodes for robust overall water splitting. The iron was used as the modulator to manipulate the electron density of NiCoP nanoarray, which could increase the positive charges of metal (Ni and Co) and P sites. The resultant electronic structure of FexCoyNi1?x?yP was supposed to balance the adsorption and desorption of H and accelerate the oxygen evolution reaction (OER) kinetics. Moreover, the morphological structure of FexCoyNi1?x?yP was modulated through the kinetically controlled alkaline etching by using the amphoteric features of initial FeCoNi hydroxide nanowires. The resultant puffed structure has rich porosity, cavity and defects, which benefit the exposure of more active sites and the transport of mass/charge. As a result, the cell integrated with the puffed quaternary FexCoyNi1?x?yP nanoarrays as both the cathode and anode only requires the overpotentials of 25 and 230 mV for hydrogen evolution reaction (HER) and OER at the current density of 10 mA cm?2 in alkaline media and a cell voltage of 1.48 V to drive the overall water splitting. Moreover, the puffed FexCoyNi1?x?yP demonstrates remarkable durability for continuous electrolysis even at a large current density of 240 mA cm?2.
关键词： water splitting,puffed nanoarray,electrocatalysis,morphology control,alkaline etching
更新于2025-09-23 15:21:01
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Theoretical design of InSe/GaTe VDW heterobilayer: A potential visible-light photocatalyst for water splitting
摘要： Using first-principles calculations, we show that two-dimensional (2D) van der Waals (vdW) InSe/GaTe heterobilayer (HBL) can serve as a potential visible-light-driven photocatalyst for water splitting to produce hydrogen, which notably improves the photocatalytic performance over isolated InSe and GaTe monolayers. The type-II band alignment and high carrier mobility of the InSe/GaTe HBL facilitate the spatial separation of photo-generated carriers and thus enhances the photocatalytic efficiency. Meanwhile, the separated absorption of H+ and OH- on the surfaces of InSe/GaTe HBL is beneficial to the photocatalytic redox reactions. Moreover, InSe/GaTe HBL can significantly extend the range of light harvesting from visible-light to infrared-light. The predicted maximum power conversion efficiency (PCE) attains 12.3%. These results indicate the InSe/GaTe HBL is a promising photocatalyst for water splitting.
关键词： water splitting,InSe/GaTe heterobilayer,photocatalyst,first-principles calculations,visible-light
更新于2025-09-23 15:21:01
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Citrus limetta Organic Waste Recycled Carbon Nanolights: Photo-electro catalytic, Sensing and Biomedical Applications
摘要： The present work reports green route-waste recycled carbon nanolights i.e. carbon dots (GCDs) synthesized via a facile one-step pyrolysis method from Citrus limetta waste pulp. The size of these obtained pristine GCDs is ~4-7 nm (HR-TEM), with high optical and structural quality as revealed by FT-IR and Raman spectroscopic analysis. They exhibit the highest quantum yield of 63.3 % over other similar green synthesized GCDs, favourable for many applications. Further, we demonstrate the multifunctional aspects of these synthesized GCDs for photo-electrochemical water splitting, photocatalytic methylene blue degradation, Fe(III) ions sensing, bactericidal activity (against E. coli and S. aureus), and bioimaging with excellent performance. The visible light active characteristic of GCDs is observed to achieve an efficient current density of ~6 mA/cm2 towards water splitting. This study demonstrates the waste to wealth potential of recycled waste derived GCDs in wide range of application domains.
关键词： GCDs,Biomedical,Green Synthesis,Waste Recycle,Dye Degradation,Water Splitting
更新于2025-09-23 15:21:01