WO3 Surface Research Articles

Role of oxygen vacancies in improving the NO gas sensing behavior of DC magnetron sputtered sub-stoichiometric WO3 thin films

Abstract WO3 thin films have been deposited on alumina substrates at different O2/Ar gas ratios and thicknesses by reactive DC magnetron sputtering for NO gas sensing. X-ray photoelectron spectroscopy (XPS) confirms the presence of oxygen vacancies in all monoclinic-phase WO3 thin films. A systematic decrease in the band gap was found with an increase in the oxygen vacancies leading to a significant upward shift in the Fermi level. Here, the influence of stoichiometry of WO3 thin film on the NO gas sensing performance is presented. It was found that the fabricated device using sub-stoichiometric WO3-x showed enhanced performance in terms of high stability, high selectivity, and fast response/recovery time with a sensor response of 147 for 50 ppm NO concentration at 275 oC, with a fast response time (~ 19 s) and recovery time (~ 17 s). The NO gas sensing of WO3 thin films has been tested at different operating temperatures (175–350 oC) and gas concentrations (1–50 ppm), witnessing a variation in sensor response. The NO gas sensing mechanism on the surface of WO3 has also been discussed.

Modelling the Impact of Argon Atoms on a WO3 Surface by Molecular Dynamics Simulations.

Machine learning potential energy functions can drive the atomistic dynamics of molecules, clusters, and condensed phases. They are amongst the first examples that showed how quantum mechanics together with machine learning can predict chemical reactions as well as material properties and even lead to new materials. In this work, we study the behaviour of tungsten trioxide (WO3) surfaces upon particle impact by employing potential energy surfaces represented by neural networks. Besides being omnipresent on tungsten surfaces exposed to air, WO3 plays an important role in nuclear fusion experiments due to the preferred use of tungsten for plasma-facing components. In this instance, the formation of WO3 is caused by the omnipresent traces of oxygen. WO3 becomes a plasma-facing material, but its properties, especially concerning degradation, have hardly been studied. We employ molecular dynamics simulations to investigate sputtering, reflection, and adsorption phenomena occurring on WO3 surfaces irradiated with Argon. The machine-learned potential energy function underlying the MD simulations is modelled using a neural network (NNP) trained from large sets of density functional theory calculations by means of the Behler-Parrinello method. The analysis focuses on sputtering yields for both oxygen and tungsten (W), for various incident energies and impact angles. An increase in Ar incident energy increases the sputtering yield of oxygen, with distinct features observed in different energy ranges. The sputtering yields of tungsten remain exceedingly low, even compared to pristine W surfaces. The ratios between the reflection, adsorption, and retention of the Ar atoms have been analyzed on their dependence of impact energy and incident end angles. We find that the energy spectrum of sputtered oxygen atoms follows a lognormal distribution and offers information about surface binding energies on the WO3 surface.

Atomically Resolved Surface Reconstruction of WO3 (002).

The rearrangement of surface atoms in oxide nanocrystals, namely surface reconstruction, plays an important role in improving the physical and chemical properties of metal oxides. However, structural information pertaining to reconstructed surfaces is scarce due to the challenges associated with directly imaging surface and sub-surface atoms under reconstruction conditions. Herein, the reconstruction of the nanocrystalline tungsten trioxide (002) surface is directly investigated via scanning transmission electron microscope (STEM). The results reveal that the atoms on the reconstructed WO3 (002) surface are rearranged into a (1 × 2) structure, and the structural model is determined by density functional theory (DFT) calculation. In addition, after surface reconstruction, the Fermi level shifted toward the conduction band compared to the initial surface, achieving an effect similar to n-type doping. Surprisingly, analogous atomic rearrangements are also observed in cracks, indicating that sub-nanometer fractures in tungsten trioxide can be remedied through surface reconstruction, thus proposing an unconventional mechanism for crack healing. Furthermore, DFT calculations are used to analyze the models and electronic properties of the reconstruction structures. These findings provide insights into the surface reconstruction of WO3 (002) and the healing of nanoscale cracks in tungsten trioxide.

Experimental and theoretical insights into the adsorption mechanism of methylene blue on the (002) WO3 surface

This work investigates the efficiency of green-synthesized WO3 nanoflakes for the removal of methylene blue dye. The synthesis of WO3 nanoflakes using Hyphaene thebaica fruit extract results in a material with a specific surface area of 13 m2/g and an average pore size of 19.3 nm. A combined theoretical and experimental study exhibits a complete understanding of the MB adsorption mechanism onto WO3 nanoflakes. Adsorption studies revealed a maximum methylene blue adsorption capacity of 78.14 mg/g. The pseudo-second-order model was the best to describe the adsorption kinetics with a correlation coefficient (R2) of 0.99, suggesting chemisorption. The intra-particle diffusion study supported a two-stage process involving surface adsorption and intra-particle diffusion. Molecular dynamic simulations confirmes the electrostatic attraction mechanism between MB and the (002) WO3 surface, with the most favorable adsorption energy calculated as -0.68 eV. The electrokinetic study confirmed that the WO3 nanoflakes have a strongly negative zeta potential of -31.5 mV and a uniform particle size of around 510 nm. The analysis of adsorption isotherms exhibits a complex adsorption mechanism between WO3 and MB, involving both electrostatic attraction and physical adsorption. The WO3 nanoflakes maintained 90% of their adsorption efficiency after five cycles, according to the reusability tests.

Cu(111)-supported W3Ox clusters: Stoichiometry and symmetry effects on CO2 activation and dissociation

Density functional calculations with dispersion corrections (DFT-D) have been performed to study the adsorption and dissociation of CO2 on W3Ox/Cu(111) inverse catalyst (x = 9 or 6). The W3O9 aggregate adsorbs in several different geometries through the formation of O-Cu bonds, in all the cases taking electronic charge from the metal surface. The reduced W3O6 particle anchors very strongly to Cu by means of W-Cu bonds; in this case, the charge transfer is opposite than for W3O9/Cu yielding the oxide particle positively charged. CO2 is activated on W3O6/Cu(111) at the oxide/metal interface; its dissociation was found to be exothermic and kinetically more favorable than on the pure counterparts, Cu(111) and WO3(001) surfaces. In contrast, CO2 is activated on W3O9/Cu(111) only in the form that is by far the least stable (the one possessing Cs symmetry). Our results suggest that stoichiometry and symmetry of Cu-supported W3Ox clusters play a crucial role in CO2 activation and dissociation. In particular, the mixed W3O6/Cu(111) system appears as a catalyst of great potential for reactions involving CO2 dissociation.

Pt-decorated oxygen-vacancy-tuned high temperature hydrogen-annealed WO3 as an efficient anode electrocatalyst for PEMFC

One of the most significant steps for the widespread application of Proton Exchange Membrane Fuel Cells (PEMFC) is the development of an efficient and corrosion-resistant electrocatalyst for Hydrogen Oxidation Reaction (HOR). To achieve an enhanced electrocatalytic activity towards HOR, we developed a carbon-free electrocatalyst that performs on par with the Pt/C commercial-based catalyst. Pt nanoparticles dispersed on hydrogenated WO3 surfaces were synthesized and experimentally shown to be an efficient HOR electrocatalyst. Furthermore, different characterizations and electrochemical studies validate the performances of all the hydrogenated samples. Pt/a-WO3/H400, hydrogenated at 400 °C, exhibits excellent electrocatalytic activity in terms of onset potential, limiting current density, and electrochemical surface area (ECSA). The membrane electrode assembly (MEA) was fabricated, and its single-cell performance was carried out using Pt/a-WO3/H300, Pt/a-WO3/H400, and Pt/a-WO3/H500 at the anode with Pt loading of 0.125 mg/cm2. The single-cell performance of Pt/a-WO3/H400 as anode electrocatalyst has the highest power density (540 mW/cm2) at 50 °C and high durability, compared to Pt/C. The enhanced electrocatalytic performance is attributed to the synergistic catalytic effect between Pt nanoparticles and the WO3-x interface. This occurs due to the preferential orientation of the highly active (002) facet and the creation of an optimum amount of oxygen vacancies due to the hydrogenation impact.

Gas sensing performance regulating of ZIF-8 encapsulated WO3 nanosheets

Reasonably regulating the adsorption properties on the surface of metal oxide semiconductors (MOS) to enhance sensor selectivity remains a challenge, limiting their application in detecting diseases biomarkers in human exhaled gas. To address this, we proposed a metal-organic frameworks (MOFs) encapsulated strategy to provide a gas-selective permeable nano-filtration layer for MOS gas sensors. By adjusting the coating thickness of ZIF-8, we successfully modulate the sensing properties of WO₃ to different potential biomarkers. The optimized WO₃/ZIF-8 composite shows improved selectivity and response to various disease biomarkers compared to WO₃ alone. The unique porous structure of ZIF-8 and the heterojunction of WO3/ZIF-8 synergistically promote the gas adsorption performance. QCM test results confirm that ZIF-8 modification effectively regulates gas adsorption on the WO₃ surface. This study provides a valuable reference for designing exhaled gas sensor arrays for detecting serious diseases.

Observation on Switching Properties of WO3-Based H2 Sensor Regulated by Temperature and Gas Concentration.

Transition metal oxide semiconductors have great potential for use in H2 sensors, but in recent years, the strange phenomena about gas-sensitive performance associated with their special properties have been more widely discussed in research. In some cases, the resistance of transition metal oxide gas sensors will emerge with some changes contrary to their intrinsic semiconductor characteristics, especially in gas sensor research of WO3. Based on the hydrothermal synthesis of WO3, our work focuses on the abnormal change of tungsten oxide resistance to different gases at low temperature (80-200 °C) and high temperature (above 200 °C). Through in situ FT-IR and in situ XPS, combined with density functional theory calculations, a new reasonable explanation of WO3 is proposed for the abnormal resistance change caused by temperature and the strange response due to gas concentration. The occurrence of these findings can be attributed to the synergistic effect resulting from the presence of two contributing factors. One of them is attributed to the alteration in the surface valence state of WO3 induced by gas, resulting in the reduction of W6+. The other one is due to the reaction between gas and adsorbed oxygen on the surface of WO3. This work presents a novel and rational concept for addressing the reaction mechanism between gas and transition metal oxide semiconductors, thereby paving the way for the development of highly efficient gas sensors based on transition metal oxide semiconductors.

Controlling of Crystal Facets by Dysprosium-Modified WO3/Carbon Nanofibers Enhance the Flexible Supercapacitor Performance.

Dysprosium-modified tungsten oxide/carbon nanofibers (Dy-WO3/PCNFs) are fabricated via electrospinning combined with high-temperature calcination to synthesize a flexible, self-supporting electrode material that does not require a conductive agent or binder. XRD and TEM analyses showed that introducing dysprosium promoted the preferential growth of WO3 crystals along the preponderance crystal planes involved in the electrochemical reaction, enhancing the exposure of the (002) and (200) crystal planes. Furthermore, DFT calculations demonstrated that the incorporation of Dy resulted in enhanced adsorption of Dy-WO3 by PCNFs, with an adsorption energy of -1.21eV. The Bader charge results indicate a transfer of 1.70 |e| from PCNFs to Dy-WO3. DFT calculations demonstrate that strong adsorption facilitates charge adsorption/desorption, which contributes to charge transfer and enhances storage capacity. The prepared Dy-WO3/PCNFs exhibited a high specific capacitance (557.28Fg-1 at 0.5Ag-1). Supercapacitors assembled with Dy-WO3/PCNFs as the positive electrode and CNFs as the negative electrode have high energy density (29.8Whkg-1 at a power density of 363.48Wkg-1). This study demonstrates the successful synthesis of Dy-WO3/PCNFs with exceptional electrochemical properties and offers significant insights into the design and application of flexible electrodes by incorporating dysprosium to modulate the crystal surface of WO3.

Unraveling the Effect of Oxygen Vacancy on WO3 Surface for Efficient NO2 Detection at Low Temperature.

Oxygen vacancies (VO) in metal oxide semiconductors play an important role in improving gas-sensing performance of chemiresistive gas sensors. Nonetheless, there is still a lack of clear understanding of the inherent mechanism of the influence of oxygen vacancies on gas sensing due to generally focusing on the concentration of VO. Herein, oxygen vacancies were rationally modulated in WO3 nanoflower structures via an annealing process, resulting in a transformation of VO from neutral (VO0) to a doubly ionized (VO2+) state. Density functional theory (DFT) calculations indicate that VO2+ is significantly more efficient than VO0 for NO2 detection in competition with atmospheric O2. Benefiting from a high concentration of VO2+, the WO3-450 (WO3 annealed at 450 °C) sensor exhibits excellent sensing performance with an ultrahigh sensitivity (3674.1 to 5 ppm NO2), superior selectivity, and long-term stability (one month). Furthermore, the sensor with the wide range of concentration detection not only can detect NO2 gas with parts per million (ppm) but also can detect NO2 with parts per billion (ppb) level concentration, with a high sensibility reaching 2.8 to 25 ppb NO2 and over 100 to 100 ppb NO2. This study elucidates the oxygen vacancy mediated sensing mechanism toward NO2 and provides an effective strategy for the rational design of gas sensors with high sensing performance.

Exploring the Gas-Sensing Mechanism of a WO3 Nanowires-Based Sensor for Ethanol Detection by Near-Ambient Pressure XPS

The WO3 nanowires (NWs), fabricated on a commercial Al2O3-based sensor platform, underwent near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) analysis during ethanol detection. Our findings revealed challenges that may appear in utilizing NAP-XPS studies for studying a real gas sensor in operando conditions. Through NAP-XPS analysis, we explored the gas-sensing mechanisms of pristine and Pt-decorated WO3 NWs for ethanol sensing at different temperatures, demonstrating a combination of several mechanisms commonly observed in metal-oxide chemiresistors. For ethanol sensing, the primary driving force for the sensor's macroscopic electrical response at low temperatures was the adsorption of ethanol molecules. Conversely, at high temperatures, it involved the adsorption of ethoxy groups along with the reducing effect of ethanol on the WO3 surface. It is shown that the surface oxygen vacancies play a crucial role in the ethanol sensing mechanism of WO3 NWs-based gas sensors. Figure 1

Construction of Ag2O/WO3-based hollow microsphere p-n heterojunction for continuous detection of ppb-level H2S gas sensor

Three-dimensional (3D) hierarchical hollow microsphere WO3 and Ag2O/WO3 heterojunction materials were prepared by a simple hydrothermal method for a highly sensitive continuous response H2S gas sensor. The results show that compared with the original WO3 (Ra/Rg=12.5, 10 ppm, 70℃), the sensor based on Ag2O/WO3 has excellent H2S sensing performance at 60℃. Including ultra-high sensitivity (Ra/Rg=207.12, 10 ppm), continuous detection of different concentrations of H2S gas (0.05–50 ppm), fast response capability (15 s), low detection limit (50 ppb), high selectivity and reliable stability. The study of gas sensing mechanism shows that the synthesized 3D hierarchical hollow microsphere structure provides more channels for gas diffusion and transmission. The dispersion of Ag2O nanoparticles (NPs) on the surface of WO3 provides more reactive sites for gas adsorption. At the same time, the charge transfer is promoted by constructing Ag2O/WO3 p-n heterojunction. Sulfurization of Ag2O improved the response value and selectivity to H2S gas. These factors together determine the superior performance of the prepared Ag2O/WO3 H2S-based sensor.

Visible light-induced photocatalytic degradation of tetrabromobisphenol A on platinized tungsten oxide

In this study, we investigated the degradation of the flame retardant tetrabromobisphenol A (TBBPA) using platinized tungsten oxide (Pt/WO3), synthesized via a simple photodeposition method, under visible light. The results of degradation experiments show a significant enhancement in TBBPA degradation upon surface platinization of WO3, with the degradation rate increasing by 13.4 times compared to bare WO3. The presence of Pt on the WO3 surface stores conduction band electrons, which facilitates the two-electron reduction of oxygen and enhances the production of valence band holes (hVB+) and hydroxyl radicals (●OH). Both hVB+ and ●OH are significantly involved in the degradation of TBBPA in the visible light-irradiated Pt/WO3 system. This was verified through fluorescence spectroscopy employing coumarin as a chemical probe and oxidizing species-quenching experiments. The analysis of degradation products and their toxicity assessment demonstrate that the toxicity of TBBPA-contaminated water is significantly reduced after Pt/WO3 photocatalysis. The degradation rate of TBBPA increased with increasing Pt/WO3 dosage, reached an optimum at a Pt content of 0.5 wt%, but decreased with increasing TBBPA concentration. The decrease in degradation efficiency of Pt/WO3 was minor, both in the presence of various anions and after repeated use. This study proposes that Pt/WO3 is a viable photocatalyst for the degradation of TBBPA in water under visible light.

Insight into selectivity of photocatalytic methane oxidation to formaldehyde on tungsten trioxide

Tungsten trioxide (WO3) has been recognized as the most promising photocatalyst for highly selective oxidation of methane (CH4) to formaldehyde (HCHO), but the origin of catalytic activity and the reaction manner remain controversial. Here, we take {001} and {110} facets dominated WO3 as the model photocatalysts. Distinctly, {001} facet can readily achieve 100% selectivity of HCHO via the active site mechanism whereas {110} facet hardly guarantees a high selectivity of HCHO along with many intermediate products via the radical way. In situ diffuse reflectance infrared Fourier transform spectroscopy, electron paramagnetic resonance and theoretical calculations confirm that the competitive chemical adsorption between CH4 and H2O and the different CH4 activation routes on WO3 surface are responsible for diverse CH4 oxidation pathways. The microscopic mechanism elucidation provides the guidance for designing high performance photocatalysts for selective CH4 oxidation.

Construction of n-n heterojunction copper manganese spinel/mesoporous WO3 photocatalyst for efficient H2 evolution rate from aqueous glycerol

Mesoporous metal oxides can expedite charge separation and mobility and give enormous active sites for H2 production. Herein, n-n heterojunction CuMn2O4/WO3 nanocomposites were constructed by a sol-gel procedure employing F-127 surfactant. The synthesized CuMn2O4/WO3 photocatalysts have been evaluated for H2 evolution from aqueous glycerol as an electron donor under visible illumination. XRD patterns of the synthesized CuMn2O4/WO3 nanocomposite manifested the formation of the monoclinic structure of WO3 and crystalline cubic CuMn2O4 spinel. The TEM image of WO3 NPs showed quasi-spherical ∼10–20 nm and CuMn2O4 NPs ∼10 nm were regularly dispersed on the surface of WO3. The optimum 12%CuMn2O4/WO3 nanocomposite exhibited a significant enhancement photocatalytic ability with the maximal H2 evolution rate (2856.6 μmol h−1g−1), which is about of 14.4 -fold higher than WO3 NPs. The optimal photocatalyst dosage is 2.4 g/L with a large evolution rate of 3427.2 μmol h−1g−1. The close interfacial connection existing between CuMn2O4 and WO3 with S-scheme mechanism and active charge separation generated the high H2 yield. The H2 evolution experiments for 45 h using CuMn2O4/WO3 nanocomposite are stable with high efficiency after five cyclings. This superb H2 evolution rate was utilized from the design of proper bandgap energy; the fostered light harvest, and the enhancement of separation efficiency photocarriers. The resultant CuMn2O4/WO3 nanocomposites exhibit a favorable photocatalyst for sustainability where it is effectively utilized in glycerol by-product through the renewable solar illumination to produce H2 and cleanly water concomitantly.

Cyclodextrin-Assisted Surface-Enhanced Photochromic Phenomena of Tungsten(VI) Oxide Nanoparticles for Label-Free Colorimetric Detection of Phenylalanine.

Herein are presented the results of experiments designed to evaluate the effectiveness of host-guest interactions in improving the sensitivity of colorimetric detection based on surface-enhanced photochromic phenomena of tungsten(VI) oxide (WO3) nanocolloid particles. The UV-induced photochromic coloration of WO3 nanocolloid particles in the presence of aromatic α-amino acid (AA), l-phenylalanine (Phe) or l-2-phenylglycine (Phg), and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TMβCDx) in an aqueous system was investigated using UV-vis absorption spectrometry. The characteristics of the adsorption modes and configurations of AAs on the WO3 surface have also been identified by using a combination of adsorption isotherm analysis and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). A distinct linear relationship was observed between the concentration of AAs adsorbed on the WO3 nanocolloid particles and the initial photochromic coloration rate in the corresponding UV-irradiated colloidal WO3 in aqueous media, indicating that a simple and sensitive quantification of AAs can be achieved from UV-induced WO3 photochromic coloration without any complicated preprocessing. The proposed colorimetric assay in the Phe/TMβCDx/WO3 ternary aqueous system had a linear range of 1 × 10-8 to 1 × 10-4 mol dm-3 for Phe detection, with a limit of detection of 8.3 × 10-9 mol dm-3. The combined results from UV-vis absorption, ATR-FTIR, and adsorption isotherm experiments conclusively indicated that the TMβCDx-complexed Phe molecules in the Phe/TMβCDx/WO3 ternary aqueous system are preferentially and strongly inner-sphere adsorbed on the WO3 surface, resulting in a more significant surface-enhanced photochromic phenomenon. The findings in this study provided intriguing insights into the design and development of the "label-free" colorimetric assay system based on the surface-enhanced photochromic phenomenon of the WO3 nanocolloid probe.

A new insight into vacancy modulation in lead-doped tungsten oxide nonarchitect for photoelectrochemical water splitting: An experimental and density functional theory approach

In this study, the impact of lead (Pb) doping on the photoelectrochemical (PEC) water splitting performance of tungsten oxide (WO3) photoanodes was investigated through a combination of experimental and theoretical approaches. Pb-doped WO3 nanostructured thin films were synthesized hydrothermally, and extensive characterizations were conducted to study their morphologies, band edge, optical and photoelectrochemical properties. Pb-doped WO3 exhibited efficient carrier density and charge separations by reducing the charge transfer resistance. The 0.96 at% Pb doping shows a record photocurrent of ∼ 1.49 mAcm−2 and ∼ 3.44 mAcm−2 (with the hole scavenger) at 1.23 V vs. RHE besides yielding a high charge separation and Faradaic efficiencies of ∼ 86 % and > 90 %, respectively. A shift in the Fermi level towards the conduction band was also observed upon the Pb doping. Additionally, density functional theory (DFT) simulations demonstrated the changes in the density of states and bandgap upon Pb doping, exhibiting favorable changes in the surface and bulk properties of WO3.

Epitaxial heterostructure of CdIn2S4/WO3 with the tunable built-in field for efficient photocathodic protection of 304SS and Q235

Photocathodic protection (PCP) can convert solar energy into protecting marine metallic structures from corrosion. However, the serious photocarrier recombination in the photoanode has hindered the development of the PCP technique. This study reported a feasible approach to construct the heterojunction with a tunable built-in electric field by epitaxially growing CdIn2S4(CIS) on the surface of WO3. The light absorbance, carrier separation, and transportation were found to be strongly dependent on the built-in field, and it would enable not only protection of the 304SS but also retard the corrosion of more vulnerable Q235. Accordingly, the OCP of coupled photoelectrode shifted to -950 and -880 mVAg/AgCl for 304SS and Q235, and their photocurrent density also reached 100 and 170 μA/cm2, respectively. Notably, the PCP performance of anti-corrosion on the 304SS and Q235 was visualized by microscopy, further proving the effectiveness of the photoanode. The underlying mechanisms and different protection capabilities were discussed in detail.

92.58 % efficiency of solar-driven degradation of tetracycline solution by Pt/WO3 nanohybrid

By using the dry plasma reduction method, Pt nanoparticles were successfully immobilized into WO3 to fabricate a Pt/WO3 composite catalyst and its application as an efficient photocatalysis in solar-driven degradation of Tetracycline (TTC). As a result, Pt nanoparticles (∼5nm) are uniform and well-distributed on the surface of WO3. The bandgap of Pt/WO3 is slightly lower than that of WO3. The optimized TTC degradation efficiency reached 76.62 % and 92.58 % under visible light and 1-sun irradiation, respectively. The mineralization study further proved that at the optimum operational parameters, only 53.68 % and 71.38 % of TTC compounds were decomposed completely into inorganic ones under compact light and 1-sun irradiation, respectively. The transformation process of TTC showed that holes and hydroxyl radicals are the main agents for TTC degradation. The removal percentage declined by 6 % after seven consecutive cycles, showing high reusability, full-scale, and practical application of Pt/WO3 material in organic compound treatment.

Mesoporous PdO–loaded WO3 nanocrystals: A promising photocatalyst for highly efficient photoreduction of nitrobenzene to aniline under visible light

BackgroundNitrobenzene (NTB) conversion to aniline (AN) is a key technology for large-scale industrial chemical production and wastewater treatment. Accordingly, photocatalytic reduction of nitrobenzene has emerged as a green technology to produce aniline. MethodsThis study offers a simple nontoxic surfactant-assisted fabrication of mesoporous tungsten oxide (WO3) nanostructures accompanied by the incorporation of tiny contents (0.5‒2.0 wt%) of palladium oxide (PdO) nanoparticles through impregnation and calcination. Significant findingsPhysicochemical investigations of fabricated heterostructures revealed the formation of mesoporous surfaces and showed the implication of PdO loading on textural and optoelectronic characteristics of WO3. Only 2.0 wt% PdO on the WO3 surface caused a notable decline in the energy bandgap from 2.77 to 1.07 eV, confirming visible light-harvesting improvement. The prepared PdO–loaded WO3 was examined for NTB photoreduction to AN. The optimum content of 1.5 wt% PdO/WO3 (2.0 g L–1) exhibited a complete phototransformation of NTB to AN after only 40 min with excellent reusability and recyclability. The PdO loading significantly facilitated photoinduced charge carriers’ separation and mobility through the construction of Step (S)-scheme heterojunction. This work opens the door for developing semiconductor-based photocatalysis as a green process for effectively converting contaminated water into useful value-added chemicals.