WO3 Nanowires Research Articles

Robust Z-scheme g-C3N4/WO3 heterojunction photocatalysts with morphology control of WO3 for efficient degradation of phenolic pollutants

Z-scheme g-C3N4/WO3 heterojunction photocatalysts with morphology control of WO3 are facilely fabricated via a thermal-induced self-polymerization of melamine in the presence of WO3 nanowires, nanosheets and microflowers, and they are successfully applied in simulated sunlight photocatalytic degradation of two refractory phenolic pollutants, p-nitrophenol and methylparaben. The g-C3N4/WO3 heterojunctions exhibit enhanced photocatalytic removal efficiency towards the target pollutants in comparison of pristine g-C3N4 and WO3; moreover, both the ratio and morphology of WO3 influence the photocatalytic activity of g-C3N4/WO3 dramatically. At the same ratio of WO3 in heterojunctions, g-C3N4/WO3 nanowires exhibit the highest pollutants removal efficiency among three heterojunction photocatalysts. By combination of testing results including photoelectronchemistry, photoluminescence and active species trapping it is confirmed that the unique Z-scheme band alignment of g-C3N4/WO3 heterojunctions plays the dominated role to the enhanced photocatalytic activity, which not only boosts the spatial separation of charge carriers but also endows the g-C3N4/WO3 with supreme redox capacity; additionally, intimate interfacial contact between WO3 and g-C3N4 in the heterojunctions can further promote this Z-scheme-dictated charge carrier transfer and separation. Under the attack of active species like hVB+, O2− and OH radicals, the target pollutants can be oxidized deeply to harmless inorganic compounds.

Amorphous Cr2WO6-Modified WO3 Nanowires with a Large Specific Surface Area and Rich Lewis Acid Sites: A Highly Efficient Catalyst for Oxidative Desulfurization.

The oxidative desulfurization (ODS) of fuel oils is of great significance for environmental protection, and the development of efficient ODS heterogeneous catalysts is highly desired. Herein, we have designed and synthesized a novel material of amorphous Cr2WO6-modified WO3 (a-Cr2WO6/WO3) nanowires (3-6 nm) with a large specific surface area of 289.5 m2·g-1 and rich Lewis acid sites. The formation of such a unique nanowire is attributed to the adsorption of Cr3+ cations on non-(001) planes of WO3. In the ODS process, the a-Cr2WO6/WO3 nanowires can efficiently oxidize benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) to their corresponding sulfones in a quasi-microemulsion reaction system and possess the highest activity (Ea = 55.4 kJ/mol) for DBT: 99.0% of 15,000 ppm DBT with 2600 ppm S can be removed (70 °C, H2O2 as the oxidant). The improvement in ODS activity from most of WO3 catalysts is owing to the sufficient active sites and enhanced adsorption of DBT on the basis of structural features of a-Cr2WO6/WO3 nanowires. Combined with free radical capture experiments, a possible ODS mechanism of W(O2) peroxotungstate route based on surface -OH groups is reasonably proposed. Moreover, the a-Cr2WO6/WO3 nanowires have good stability and can be synthesized on a large scale, suggesting its potential applications as an efficient heterogeneous catalyst.

Synthesis of highly oriented WO3 nanowire bundles decorated with Au for gas sensing application

This study demonstrates the synthesis of self-assembled hexagonal WO3 nanowire bundles, with both ordered and random structures in the presence of SO42− ions, by a simple but efficient solvent-thermal method. The as-synthesized products are composed of hierarchical bundles with assembled ultrathin nanowire subunits. The growth and assembly mechanisms, regarding WO3 nanowire bundles, may be elucidated through oriented attachment or Ostwald ripening growth, based on a synergistic effect from both oxalic acid and ethylene glycol in dehydrating WO3·xH2O to WO3 nanocrystals and in controlling segregation behavior, along with high surface areas (18.4 m2 g-1 for ordered structures while 11.6 m2 g-1 disordered ones), which makes WO3 bundles great potential for gas sensing. To further enhance gas sensing, gold nanoparticles were chosen to deposit on the surface of WO3 nanowire bundles by acting with amino groups linked with WO3 bundles in the HAuCl4 solution with further oxidation. The Au-WO3 composites were examined towards various reducing gases, with exemplary sensitivities of (S = 127, 82), (S = 72, 52) towards n-butanol and acetone, respectively. The sensing mechanisms of such WO3 bundle structures are further understood in detail. This work will make the unique WO3 bundle nanostructures highly potential for gas sensing applications.

Formaldehyde detection with chemical gas sensors based on WO3 nanowires decorated with metal nanoparticles under dark conditions and UV light irradiation

We report results of formaldehyde gas (CH2O) detection under dark conditions and UV light irradiation with pristine tungsten trioxide nanowires (WO3 NWs) and metal nanoparticles decorated WO3 NWs gas sensing layers. The resistive layers were deposited by one step aerosol assisted chemical vapor deposition (AACVD) on commercial alumina substrates with 10-pair interdigitated platinum electrodes. The elaborated gas sensors, based on pristine WO3 and on WO3 decorated with Au, Pt, Au/Pt, Ni and Fe nanoparticles, were investigated towards three concentrations of formaldehyde gas (5, 10 and 15 ppm) under dark conditions and under UV light irradiation at the wavelength of 394 nm. Two main effects were observed: firstly, under UV light irradiation the response time for CH2O desorption was significantly reduced with the exception of the nanomaterial with Fe NPs dopant; secondly, the gas induced baseline shift was reduced under UV light irradiation conditions. These results can be explained by the additional energy induced by the UV light, accelerating the adsorption-desorption processes. The results obtained confirmed that both the decoration of WO3 NWs with selected metal nanoparticles as well as sensors operation under UV light irradiation are a practical and affordable way to enhance gas sensing towards formaldehyde detection, although both strategies applied together did not introduce an amplified synergetic effect.

A Dopant Replacement-Driven Molten Salt Method toward the Synthesis of Sub-5-nm-Sized Ultrathin Nanowires.

The high-temperature molten-salt method is an important inorganic synthetic route to a wide variety of morphological phenotypes. However, its utility is limited by the fact that it is typically incapable of producing ultrathin (<5 nm diameter) nanowires, which have a crucial role in novel nanotechnology applications. Herein, a rapid molten salt-based synthesis of sub-5-nm-sized nanowires of hexagonal tungsten oxide (h-WO3 ) that is critically dependent on a substantial proportion of molybdenum (Mo) dopant is described. This dopant-driven morphological transition in tungsten oxide (WO3 ) may be attributable to the collapse of layered structure, followed by nanocluster aggregation, coalescence, and recrystallization to form ultrathin nanowires. Interestingly, due to the structural properties of h-WO3 , the thus-formed ultrathin nanowires are demonstrated to be excellent photocatalysts for the production of ammonia (NH3 ) from nitrogen (N2 ) and water. The ultrathin nanowires exhibit a high photocatalytic NH3 -production activity with a rate of 370 µmol g-1 h-1 and an apparent quantum efficiency of 0.84% at 420 nm, which is more than twice that obtained from the best-performing Mo-doped W18 O49 nanowire catalysts. It is envisaged that the dopant replacement-driven synthetic protocol will allow for rapid access to a series of ultrathin nanostructures with intriguing properties and increase potential applications.

Assessment of Electronic Sensing Techniques for the Rapid Identification of Alveolar Echinococcosis through Exhaled Breath Analysis.

Here we present a proof-of-concept study showing the potential of a chemical gas sensors system to identify the patients with alveolar echinococcosis disease through exhaled breath analysis. The sensors system employed comprised an array of three commercial gas sensors and a custom gas sensor based on WO3 nanowires doped with gold nanoparticles, optimized for the measurement of common breath volatile organic compounds. The measurement setup was designed for the concomitant measurement of both sensors DC resistance and AC fluctuations during breath samples exposure. Discriminant Function Analysis classification models were built with features extracted from sensors responses, and the discrimination of alveolar echinococcosis was estimated through bootstrap validation. The commercial sensor that detects gases such as alkane derivatives and ethanol, associated with lipid peroxidation and intestinal gut flora, provided the best classification (63.4% success rate, 66.3% sensitivity and 54.6% specificity) when sensors’ responses were individually analyzed, while the model built with the AC features extracted from the responses of the cross-reactive sensors array yielded 90.2% classification success rate, 93.6% sensitivity and 79.4% specificity. This result paves the way for the development of a noninvasive, easy to use, fast and inexpensive diagnostic test for alveolar echinococcosis diagnosis at an early stage, when curative treatment can be applied to the patients.

Effect of Annealing on Morphology and Photoluminescence of WO₃ Nanowires Deposited by Glancing Angle Deposition Techniques.

In this article, vertically aligned WO₃ nanowires were synthesized by employing the glancing angle deposition technique. The significant improvement in the crystallinity and surface morphology of the synthesized WO₃ nanowires were observed for 500 °C annealed samples and beyond that temperature it starts degrading. The X-ray diffraction confirmed the different phase transition after annealing. Increase in crystallite size from 68.93 nm to 77.41 nm was observed with the increase in annealing temperature from 300 °C to 500 °C. Upon 250 nm excitation, a broad blue emission aroused by near band edge emission is observed. Also, other emission peaks were observed due to the localized states of oxygen vacancies in the conduction band of WO₃. Fourier transform infrared result shows the bonding of WO₃ nanowires and intensity were greatly enhanced as the annealing temperature increases up to 500 °C. These enhancements in the properties could be applicable for the development of WO₃ based nanodevices.

Facile Preparation of WO3 Nanowires by Bubble-Electrospinning and their Photocatalytic Properties.

As a relatively novel and promising method, the bubble electrospinning is to fabricate continuous and uniform nanowires using an aerated polymer solution in an electric field. A large number of oxidized docking nanowires were established on a silicon substrate using the bubble electrospinning, and then using Tungsten Oxide Ammonium (AMT) as an appropriate calcined air with the WO3 sources. WO3 production can enhance its catalytic activity, stability, and can raise its rhodamine B degradation rate as well; the prospect of its wide application. The high aspect ratio of WO3 nanowires is successfully prepared by a lightweight bubble electrospinning technique using Polyoxyethylene (PEO) and Ammonium-Tungstate (AMT) as the WO3 precursor after annealing in air at 400, 450 and 500°C, respectively. The products were characterized by SEM, FTIR, XRD, and TG analysis. This Paper reviews the related patents on bubble electrospinning and WO3 nanowires. The results were shown that the diameter of WO3 nanowires ranges from 2μm to 450nm, which varies with the calcination temperature. XRD diffraction and infrared spectroscopy showed that monoclinic crystals were prepared at different calcination temperatures (400, 450 and 500°C). In addition, the UV-vis diffuse reflectance spectroscopy showed that the fiber had a bandgap energy of 2.63 eV after calcination at 450oC, showing excellent photocatalytic activity in the degradation of Rh B at 245 nm. The preparation of WO3 nanowires by bubble electrospinning method is a feasible patented technology.

Ultra-long high quality catalyst-free WO3 nanowires for fabricating high-performance visible photodetectors

This work presents a study on the controlled growth of WO3 nanowires via chemical vapor deposition without catalyst, and their potential applications in visible photodetectors. The influence of growth conditions on the morphology of WO3 nanowires is studied in order to understand the growth mechanism of WO3 nanowires, and ultra-long (60 , the longest one ever reported) WO3 nanowires with a spindle shape are achieved by optimizing the growth conditions. It was found that the length of WO3 nanowires increases from 15 to 60 with increasing the argon carrier gas flow rate from 30 sccm to 90 sccm, and then saturates with further increasing the argon carrier gas flow rate. However, the length of WO3 nanowires reduces from 60 to 19 with increasing the tube inner pressure from 2.5 Torr to 3.5 Torr. The photoconductor detectors based on WO3 single nanowires present excellent device performance with a responsivity as high as 19 A W−1 at a bias of 0.1 V, a detectivity as high as 1.06 × 1011 Jones, and a response (rising and decay) time as short as 8 ms under the illumination of a 404 nm laser. These results indicate the great potential of WO3 nanowires for applications in fabricating high performance visible photodetectors.

Cuprous ion (Cu+) doping induced surface/interface engineering for enhancing the CO2 photoreduction capability of W18O49 nanowires

Solar-driven reduction of CO2 and H2O into fuels is a promising approach for addressing global warming and energy crisis. Herein, Cu+ doped W18O49 nanowires were prepared by a facile solvothermal method and applied in photocatalytic reduction of CO2. The composition and structure of pristine and Cu+ doped W18O49 samples have been characterized. It was found that the morphology of W18O49 nanowires was changed with increasing amounts of dopant. The photocatalytic CO2 reduction activity of W18O49 nanowires and the Cu+ doped W18O49 samples were evaluated using H2O as reducing agent. The strategy of Cu+ doping not only could affect the band edge position and the surface wettability, but also influenced separation of the photogenerated electron-hole pairs. It was found that Cu+ doping could introduce oxygen vacancy and change the conduction edge to a more negative position for W18O49 nanowires, which might be beneficial for the activation of CO2 and promote the following CO2 reduction. Furthermore, the higher separation efficiency of photogenerated electron-hole pairs with Cu+ doping could contribute to the CO2 photoreduction enhancement. In addition, the Cu+ doped W18O49 nanowires (Cu-W18O49-0.005) presented a relatively poor hydrophilic property, which might be beneficial for the adsorption of CO2 molecules and contribute to its superior photocatalytic CO2 reduction capability.

Ultrathin low dimensional heterostructure composites with superior photocatalytic activity: Insight into the multichannel charge transfer mechanism

Abstract Multi-level and multi-angle designations of photocatalysts have attracted great attention to address the insufficient photogenerated charge generation and transformation in photocatalysis. In this study, we reported an ultrathin 1D/2D W18O49/g-C3N4 nanocomposites with unique multiscale structure and electronic property through direct growth of 1D plasmonic W18O49 nanowires onto the surface of 2D ultrathin g-C3N4 nanosheets. Owing to the unique multiscale structure and electronic property, the synthesized nanocomposites present enhanced photocatalytic activity, owns the maximum removal efficiency of 96.3% and rate constant of 0.0464 min−1 for Ibuprofen (IBF) after 60 min under AM 1.5G light. Meanwhile, under near-infrared (NIR) light irradiation, the optimum UWN-3 present 39.2% removal efficiency of IBF and the reaction rate reached 0.0027 min−1 after 120 min. Additionally, the degradation pathway indicated that the decarboxylation process was the main decomposition route of IBF in this reaction system, and OH radical species attack process also contributed to the degradation of IBF. Scavenge experiments and mechanism analysis illustrated that IBF degradation in this reaction system mainly depends on h+, O2– and OH radical species, and the promoted photocatalytic performance of the synthesized ultrathin 1D/2D W18O49/g-C3N4 nanocomposites are stem from the synergism of the multichannel photogenerated charge transfer pathways. The combination of the multichannel charge transfer pathways mentioned above resulted in the highly efficient photocatalytic activity of the ultrathin 1D/2D W18O49/g-C3N4 nanocomposites.

Fabrication of a Micro-Electromechanical System-Based Acetone Gas Sensor Using CeO2 Nanodot-Decorated WO3 Nanowires.

Preparation of reliable, stable, and highly responsive gas-sensing devices for the detection of acetone has been considered to be a key issue for the development of accurate disease diagnosis systems via exhaled breath. In this paper, novel CeO2 nanodot-decorated WO3 nanowires are successfully synthesized through a sequential hydrothermal and thermolysis process. Such CeO2 nanodot-decorated WO3 nanowires exhibited a remarkable enhancement in acetone-sensing performance based on a miniaturized micro-electromechanical system device, which affords high response (S = 1.30-500 ppb, 1.62-2.5 ppm), low detection limit (500 ppb), and superior selectivity toward acetone. The improved performance of the acetone sensor is likely to be originated from the fast carrier transportation of WO3 nanowires, the formation of WO3-CeO2 heterojunctions, and the existence of large amounts of oxygen vacancies in CeO2. The improved reaction thermodynamics and sensing mechanisms have also been revealed by the specific band alignment and X-ray photoelectron spectroscopy analysis.

Mo-doped WO3 nanowires for adsorbing methylene blue dye from wastewater

Doping tungsten oxide with other metals is a promising approach for obtaining improved properties as compared with its undoped counterpart. Here, the effect of molybdenum doping on the morphology, crystalline structure, and adsorption properties of nanostructured WO3 was investigated. Undoped and Mo-doped hexagonal WO3 (h-WO3) nanowire bundles were synthesized by hydrothermal method. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, scanning transmission electron microscopy, selected-area electron diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. The surface areas of the samples were evaluated by N2 adsorption–desorption isotherm, and their adsorption properties were evaluated based on their ability to adsorb cationic dye methylene blue (MB) in aqueous solution. Upon the addition of molybdenum, the morphology of the h-WO3 nanowire changes from large bundles to narrow bundles with a higher number of isolated thin nanowires. Mo doping also has changed the crystalline structure, porosity, and surface area of the bundled h-WO3 nanowires. Interestingly, Mo-doped h-WO3 nanowire bundles exhibit an enhanced and faster MB uptake, thus implying that Mo-doping WO3 can be an effective strategy to improve the adsorption properties, thereby adding value in developing alternative adsorption-based methods for wastewater treatment.

Photoelectrochemical oxygen evolution with cobalt phosphate and BiVO4 modified 1-D WO3 prepared by flame vapor deposition

We demonstrate the cobalt phosphate (Co-Pi) modified 1-D WO3/BiVO4 nanowire heterojunction photoanode as oxygen evolution catalyst for photoelectrochemical (PEC) water splitting application. WO3 nanowires were prepared by flame vapor deposition (FVD) process and BiVO4 nanoparticles were spin-coated on top of WO3 nanowires. In order to improve oxygen evolution kinetics, WO3/BiVO4 heterojunction photoanode was modified by photo-assisted electrodeposition of Co-Pi. Co-Pi improve the PEC water oxidation efficiency of 1 D-WO3/BiVO4 by reducing the charge recombination, facilitating the hole transfer and reducing the overpotential of oxygen evolution reaction. The optimum amount of Co-Pi for high photocurrent density was proposed. The loaded Co-Pi has enhanced the overall PEC performance showing largely shifted onset potential (∼450mV) with significantly increased photocurrent (2.7 times at 1.23V vs. RHE). The prepared composite photoanode of 1-D WO3/BiVO4/Co-Pi shows the higher incident photon to current efficiency and applied bias photon-to-current efficiency than without Co-Pi loading. We obtain the highest level of PEC performance with WO3/BiVO4/Co-Pi heterojunction composite photoanode which is based on 1-D framework of WO3 prepared by facile, rapid and economical FVD in this study.

Enhanced core–shell CeO2:Er,Yb@W18O49 heterojunction H2 generation by multiband emissions of Er ions

The core–shell CeO2:Er,Yb@W18O49 heterojunction is successfully synthesized via the facile solvothermal method. The octahedral CeO2:Er,Yb nanocrystal’s core exhibits green (2H11/2, 4S3/2 → 4I15/2), red (4F9/2 → 4I15/2) and NIR (4I11/2 → 4I15/2 and 4I13/2 → 4I15/2) emission under 980 nm laser diode excitation, and the multiband emissions are absorbed by the W18O49 nanowire’s shell, re-exciting its higher energy localized surface plasmon resonances (LSPR). With the excitation of 980 nm, the photocatalytic property of CeO2:Er,Yb@W18O49 for hydrogen (H2) evolution from ammonia borane (BH3NH3), a three-fold increase compared to W18O49, is researched. The application of natural sunlight for the production of H2 is studied, and an obvious H2 production enhancement compared to the use of W18O49 (two-fold) is also observed. This remarkable enhancement in the catalytic activity of CeO2:Er,Yb@W18O49 heterostructures is ascribed to the re-excitation of LSPR by multiband emissions of CeO2:Er,Yb.

Nanowires-assembled WO3 nanomesh for fast detection of ppb-level NO2 at low temperature

Hierarchical WO3 nanomesh, assembled from single-crystalline WO3 nanowires, is prepared via a hydrothermal method using thiourea (Tu) as the morphology-controlling agent. Formation of the hierarchical architecture comprising of WO3 nanowires takes place via Ostwald ripening mechanism with the growth orientation. The sensor based on WO3 nanomesh has good electrical conductivity and is therefore suitable as NO2 sensing material. The WO3 nanomesh sensor exhibited high response, short response and recovery time, and excellent selectivity towards ppb-level NO2 at low temperature of 160 ℃. The superior gas performance of the sensor was attributed to the high-purity hexagonal WO3 with high specific surface area, which gives rise to enhanced surface adsorption sites for gas adsorption. The electron depletion theory was used for explaining the NO2-sensing mechanism by the gas adsorption/desorption and charge transfer happened on the surface of WO3 nanomesh.

Facile synthesis of ultrafine rGO/WO3 nanowire nanocomposites for highly sensitive toxic NH3 gas sensors

We introduce a facile and scalable synthesis of rGO/WO3 nanocomposites by hydrothermal method for gas sensing applications. The characterization of rGO/WO3 nanocomposites by some advanced techniques such as scanning electron microscopy, high resolution transmission electron microscopy and Raman spectroscopy revealed that high quality rGO/WO3 nanocomposites included single crystal WO3 nanowires (average diameter of 10 nm) entangled by thin rGO layers. Sensing measurements demonstrated that the rGO/WO3 nanocomposite-based sensor can detect highly toxic NH3 gas at low concentrations ranging from 20 ppm to 500 ppm and fulfills practical applications. The developed gas sensors based on rGO/WO3 nanocomposites have significant application prospects in environment pollution monitoring at detection limit of about 138 ppb. We also discussed the gas sensing mechanism of the rGO/WO3 nanocomposites based on the p-n junction.

Excess conductivity investigations of WO3 nanowires added to YBa2Cu3O7-d superconductor

Series of YBa2Cu3O7-d + x wt% WO3 nanowire mixtures where x = 0.0–2.0 wt% were prepared via solid-state reaction method. X-ray diffraction (XRD) patterns show the unaffected orthorhombic structure in various composites. Scanning electron microscopy (SEM) micrographs show the increase in grains size and the filling of voids between grains by WO3 nanowires. The superconducting transition temperatures deduced from electrical resistivity versus temperature (ρ(T)) measurements are almost unchanged by lower WO3 nanowires addition (i.e., x 0.5 wt%). The analysis of excess conductivity fluctuation (∆σ) by means of Aslamazov–Larkin (AL) and Lawrence–Doniach (LD) approaches was investigated. Dimensional fluctuations, coherence lengths, effective layer thickness, zero temperature lower and upper critical magnetic fields (Bc1 (0) and Bc2 (0)), and critical current density at temperature T = 0 K (Jc(0)) were extracted and discussed in relation with the structure and morphology. Improvements in Bc1 (0), Bc2 (0), and Jc(0)) were noticed for samples added with lower WO3 nanowires content, particularly for x = 0.1 wt% composite sample.

Wavelength-Dependent Solar N2 Fixation into Ammonia and Nitrate in Pure Water.

Solar-driven N2 fixation using a photocatalyst in water presents a promising alternative to the traditional Haber-Bosch process in terms of both energy efficiency and environmental concern. At present, the product of solar N2 fixation is either NH4+ or NO3−. Few reports described the simultaneous formation of ammonia (NH4+) and nitrate (NO3−) by a photocatalytic reaction and the related mechanism. In this work, we report a strategy to photocatalytically fix nitrogen through simultaneous reduction and oxidation to produce NH4+ and NO3− by W18O49 nanowires in pure water. The underlying mechanism of wavelength-dependent N2 fixation in the presence of surface defects is proposed, with an emphasis on oxygen vacancies that not only facilitate the activation and dissociation of N2 but also improve light absorption and the separation of the photoexcited carriers. Both NH4+ and NO3− can be produced in pure water under a simulated solar light and even till the wavelength reaching 730 nm. The maximum quantum efficiency reaches 9% at 365 nm. Theoretical calculation reveals that disproportionation reaction of the N2 molecule is more energetically favorable than either reduction or oxidation alone. It is worth noting that the molar fraction of NH4+ in the total product (NH4+ plus NO3−) shows an inverted volcano shape from 365 nm to 730 nm. The increased fraction of NO3− from 365 nm to around 427 nm results from the competition between the oxygen evolution reaction (OER) at W sites without oxygen vacancies and the N2 oxidation reaction (NOR) at oxygen vacancy sites, which is driven by the intrinsically delocalized photoexcited holes. From 427 nm to 730 nm, NOR is energetically restricted due to its higher equilibrium potential than that of OER, accompanied by the localized photoexcited holes on oxygen vacancies. Full disproportionation of N2 is achieved within a range of wavelength from ~427 nm to ~515 nm. This work presents a rational strategy to efficiently utilize the photoexcited carriers and optimize the photocatalyst for practical nitrogen fixation.

Anchoring of black phosphorus quantum dots onto WO3 nanowires to boost photocatalytic CO2 conversion into solar fuels.

A 0D-1D direct Z-scheme heterojunction consisting of black phosphorus quantum dots (BPQDs) anchored onto WO3 nanowires was well designed. Kelvin probe force microscopy studies provide direct evidence for charge transfer and separation between BPQDs and WO3 in a single nanowire, confirming the Z-scheme model. The BPQD-WO3 heterojunction displays excellent performance of photocatalytic reduction of CO2, exhibiting not only highly efficient carbon monoxide solar fuel conversion, but also a significant amount of ethylene (C2H4), a highly value-added hydrocarbon species, rarely reported in previous photocatalysis processes. Both experimental and theoretical calculations demonstrate that BPQD plays a critical role in photocatalytic formation of C2H4 from CO2.