Search Results (41)

The advancement of photocatalytic materials is critical for addressing environmental challenges such as water remediation, where efficient, robust, and reusable systems are in high demand. In this search, the development of hierarchically organized photocatalytic configurations with spatial control over active sites can significantly enhance performance. With this in mind, we present here a novel biomimetic approach for the patterned growth of TiO₂-ZnO photocatalytic heterostructures using solid-binding peptides (SBPs) as molecular linkers. Specifically, using bi-functional SBPs with selective affinity for both oxides, we achieve site-specific, molecularly guided deposition of TiO₂ nanoparticles onto pre-patterned ZnO-coated substrates. Leveraging the specific recognition capabilities and strong binding affinities of the engineered SBPs, the proposed biomimetic methodology allows for the fabrication of well-organized hybrid nanostructures under sustainable conditions. Photocatalytic degradation assays employing methyl orange as a model contaminant indicate that the patterned architecture enhances both the accessibility of the active photocatalytic sites and the recoverability of the material. This reusability is a critical parameter for the practical deployment of photocatalytic systems in water purification technologies. The obtained results underscore the potential of SBP-mediated molecular recognition as a versatile tool for green nanofabrication of functional materials with advanced architectural and catalytic properties. Full article

Electro-oxidation of urea (UOR) in alkaline medium is one of the most effective alternative ways of producing green hydrogen, as the oxidation potential in UOR is less and thermodynamically more favorable than conventional water oxidation. The development of cost-effective materials in catalyzing UOR is recently seeking more attention in the research hotspot. Suitably modifying the Ni-based catalysts towards active site creation and preventing surface passivation is much important in this context, following which we reported the synthesis of Ni₃S₂ (NS) supported with CuCo (CC) bimetallic (NSCC). A simple hydrothermal route for NS synthesis and the electrodeposition method for CuCo (CC) deposition is adapted in a self-supported manner. The NS and CC catalysts exhibited sheet-like morphology, as confirmed by SEM and TEM analysis. The bimetallic CC deposition prevented the surface passivation of nickel sulfide (NS) over oxygen evolution reaction (OER) and improved the charge-transfer kinetics. The NSCC catalyst catalyzed UOR in an alkaline medium, which required a lower potential of 1.335 V vs. RHE to attain the current density of 10 mAcm⁻², with a lower Tafel slope value of 131 mVdec⁻¹. In addition, a two-electrode cell setup is constructed with an operating cell voltage of 1.512 V for delivering 10 mAcm⁻² current density. This study illustrates the new strategy of designing heterostructure catalysts for electrocatalytic UOR. Full article

In response to escalating global energy demands and environmental challenges, electrochromic (EC) smart windows have emerged as a transformative technology for adaptive solar modulation. Herein, we report the rational design and fabrication of a bilayer WO₃/TiO₂ heterostructure via a synergistic two-step strategy involving the electrochemical deposition of amorphous WO₃ and the controlled hydrothermal crystallization of TiO₂. Structural and morphological analyses confirm the formation of phase-pure heterostructures with a tunable TiO₂ crystallinity governed by reaction time. The optimized WTi-5 configuration exhibits a hierarchically organized nanostructure that couples the fast ion intercalation dynamics of amorphous WO₃ with the interfacial stability and electrochemical modulation capability of crystalline TiO₂. Electrochromic characterization reveals pronounced redox activity, a high charge reversibility (98.48%), and superior coloration efficiency (128.93 cm²/C). Optical analysis confirms an exceptional transmittance modulation (ΔT = 82.16% at 600 nm) and rapid switching kinetics (coloration/bleaching times of 15.4 s and 6.2 s, respectively). A large-area EC device constructed with the WTi-5 electrode delivers durable performance, with only a 3.13% degradation over extended cycling. This study establishes interface-engineered WO₃/TiO₂ bilayers as a scalable platform for next-generation smart windows, highlighting the pivotal role of a heterostructure design in uniting a high contrast, speed, and longevity within a single EC architecture. Full article

In this study, nitrogen-doped TiO₂ heterojunction materials were successfully synthesized via a facile one-step solvothermal approach. A range of advanced characterization techniques were employed to thoroughly analyze the structural and compositional properties of the synthesized photocatalysts, and their application potential for tetracycline (TC) degradation under visible light was studied. The results indicated that N-doped TiO₂ exhibited a well-defined hierarchical micro/nanostructure and formed an efficient anatase/rutile homogeneous heterojunction. The photocatalytic performance of N-TiO₂ for TC degradation under visible light was significantly enhanced, achieving a degradation efficiency of up to 87% after 60 min of irradiation. This improvement could be attributed to the synergistic effects of optimal nitrogen doping, heterojunction formation, and the hierarchical micro/nanostructure, which collectively reduced the bandgap energy and suppressed the recombination rate of photogenerated carriers. Furthermore, density functional theory (DFT) calculations were conducted to systematically explore the impacts of substitutional and interstitial nitrogen doping on the energy band structure of TiO₂. Full article

Considerable levels of pollution produced by urbanization and industrial development have established a need for monitoring the presence of harmful compounds and the assessment of environmental risks to provide a basis for timely reaction and the prevention of disastrous consequences. Chemical sensors offer a reasonable solution; however, the desired properties, such as high sensitivity, selectivity, stability and reliability, ease of fabrication, and cost-effectiveness, are not always easily met. To this end, the incorporation of zeolites in sensor materials has attracted considerable attention. Such hybrid sensor materials exhibit excellent performances due to the unique properties of zeolites, which have been successfully utilized in gas-sensing applications. In this review, we discuss recent findings in the area of the application of zeolites as sensor materials, focusing on the detection of volatile organic compounds and highlighting the role of zeolite frameworks and the proposed mechanisms in the sensing process. Finally, we consider possible future directions for the development of zeolite-based sensor technology, including the application of hierarchical materials, nanosized zeolites, and 2D material–zeolite heterostructures that would fulfill industrial and environmental demands. Full article

In the present study, self-assembled hierarchical CoMn-LDH, CoMn@CuZnS, and CoMn@CuZnFeS heterostructured composites were synthesized for bifunctional applications. As an electrode for a supercapacitor, CoMn-LDH demonstrated superior areal and specific capacitance of 5.323 F cm⁻² (279.49 mAh/g) at 4 mA cm⁻², comparable to or even higher than other LDHs. The assembled AC//CoMn-LDH hybrid supercapacitor device further demonstrated better stability with 63% original capacitance over 20,000 cycles. Later, as a catalyst, CoMn-LDH, CoMn@CuZnS, and CoMn@CuZnFeS electrodes revealed better performance, with overpotentials of 340, 350, and 366 and −199, −215, and −222 mV to attain 10 mA cm⁻² of current density for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Moreover, for CoMn-LDH, small Tafel slopes of 102 and 128 mV/dec were noticed for OER and HER with good stability compared to heterostructured electrodes. Full article

As a sustainable alternative technology to the cost- and energy-intensive Haber–Bosch method, electrochemical nitrogen (N₂) reduction offers direct conversion of N₂ to NH₃ under ambient conditions. Direct use of noble metals or non-noble metals as electrocatalytic materials results in unsatisfactory electrocatalytic properties because of their low electrical conductivity and stability. Herein, three-dimensional flexible carbon nanofiber (CNF/TiO₂@CoS) nanostructures were prepared on the surface of CNF by using electrospinning, a hydrothermal method, and in situ growth. We investigated the behavior of CNFs/TiO₂@CoS as an electrocatalytic material in 0.1 M sodium sulfate. The highest ammonia yield of the material was 4.61 × 10⁻¹¹ mol s⁻¹ cm⁻² at −0.45 V vs. RHE, and the highest Faraday efficiency, as well as superior long-term durability, was 8.3% at −0.45 V vs. RHE. This study demonstrates the potential of firecracker-shaped nanofiber templates for loading varied noble metals or non-noble metals as a novel development of hybrid composites for electrocatalytic nitrogen reduction. Full article

A novel hierarchical porous biomorphic ZnO/SnO was facilely synthesized in one step using bagasse as a bio-template. The structural features of the ZnO/SnO₂ n–n heterostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results revealed that the as-prepared ZnO/SnO₂ retained the original pore morphology of the bagasse material, and the ZnO/SnO₂ was demonstrated with higher sensing performance as compared with the pure SnO₂. Particularly, when the molar ratio of SnO₂:ZnO = 1:1, the sensor displayed the highest response, showing an excellent response value of 37 under 100 ppm methanol at 340 °C. Meanwhile, the ZnO/SnO₂ composite exhibited good gas selectivity and stability to methanol, which could mainly be attributed to the formation of n-n junctions between SnO₂ and ZnO and the high capability of absorbed oxygen species of the ZnO/SnO₂ composite. Full article

In recent years, there has been significant interest in transition-metal sulfides (TMSs) due to their economic affordability and excellent catalytic activity. Nevertheless, it is difficult for TMSs to achieve satisfactory performance due to problems such as low conductivity, limited catalytic activity, and inadequate stability. Therefore, a catalyst with a heterostructure constituted of a nickel–iron-layered double hydroxide, nickel sulfide, molybdenum disulfide, and cerium dioxide was designed. At the current density of 10 mA cm⁻² in an alkaline solution, the catalyst exhibits a HER overpotential of 116 mV. In addition, an overpotential of 235 mV@150 mA cm⁻² was displayed for OER. The catalyst showed a good retention rate (94.7% for HER, 98.6% for OER) after 160 h stability tests. The excellent electrochemical performance is attributed to the following points: 1. The self-supporting three-dimensional hierarchical structure provides abundant sites, fast ion diffusion channels, and electron transfer paths, and ensures structural stability. 2. The strong interfacial electron interaction between Ni₃S₂/MoS₂ heterojunction and NiFe-LDH improves the OER reaction kinetics. 3. The Ce³⁺ and oxygen vacancies in CeO₂ promote the dissociation of H₂O and promote the HER reaction kinetics. This approach paves the way for developing highly efficient electrocatalysts for various electrochemical applications. Full article

Accessible and superior electrocatalysts to overcome the sluggish oxygen evolution reaction (OER) are pivotal for sustainable and low-cost hydrogen production through electrocatalytic water splitting. The iron and nickel oxohydroxide complexes are regarded as the most promising OER electrocatalyst attributed to their inexpensive costs, easy preparation, and robust stability. In particular, the Fe-doped NiOOH is widely deemed to be superior constituents for OER in an alkaline environment. However, the facile construction of robust Fe-doped NiOOH electrocatalysts is still a great challenge. Herein, we report the facile construction of Fe-doped NiOOH on Ni(OH)₂ hierarchical nanosheet arrays grown on nickel foam (FeNi@NiA) as efficient OER electrocatalysts through a facile in-situ electrochemical activation of FeNi-based Prussian blue analogues (PBA) derived from Ni(OH)₂. The resultant FeNi@NiA heterostructure shows high intrinsic activity for OER due to the modulation of the overall electronic energy state and the electrical conductivity. Importantly, the electrochemical measurement revealed that FeNi@NiA exhibits a low overpotential of 240 mV at 10 mA/cm² with a small Tafel slope of 62 mV dec⁻¹ in 1.0 M KOH, outperforming the commercial RuO₂ electrocatalysts for OER. Full article

The detection of trimethylamine (TMA) is critically important due to its toxic and flammable nature, which poses significant risks to human health and the environment. However, achieving high response, rapid kinetics, selectivity, and low operating temperatures in TMA sensing remains challenging. In this study, WS₂/WO₃ nanohybrids with flower-like hierarchical structures were synthesized via an in situ sulfurization process, utilizing varying amounts of thioacetamide to control the sulfurization state of WO₃. These novel hierarchical WS₂/WO₃ nanohybrids exhibit remarkable selectivity towards TMA, as well as rapid response and recovery characteristics. Specially, the optimal WS₂/WO₃ sensor, composed of 5% WS₂/WO₃ nanohybrids, demonstrates exceptional TMA sensing performance, including a high response (19.45 at 10 ppm), good repeatability, reliable long-term stability, and a low theoretical detection limit (15.96 ppb). The superior sensing capabilities of the WS₂/WO₃ nanohybrids are attributed to the formation of p-n heterojunctions at the interface, the unique hierarchical structures, and the catalytic activity of WS₂. Overall, this work provides a straightforward and versatile approach for synthesizing multifunctional nanomaterials by combining metal oxide micro-flowers with transition metal dichalcogenide nanoflakes for applications in monitoring TMA in complex environments. Full article

Molybdenum diselenide (MoSe₂) is a promising anode for alkali-ion storage due to its intrinsic advantages. However, MoSe₂ still encounters the issues of structural instability and poor rate performance caused by drastic volume change and sluggish reaction kinetics. Reasonable design of electrode structure is crucial for achieving superior electrochemical performance. Herein, a novel hierarchical structure coupled with 1D/1D subunits is elaborately designed and constructed, in which the MoSe₂/CoSe₂ heterostructure is the “trunk” and the N-doped carbon nanotubes are the “branches” (MoSe₂/CoSe₂/NCNTs). Benefiting from the properties endowed by unique configurations, MoSe₂/CoSe₂/NCNTs electrodes manifest faster reaction kinetics and better structure durability. Evaluated as an anode for LIBs and SIBs, MoSe₂/CoSe₂/NCNTs deliver high reversible capacity, superior rate capability (452 at 10 A g⁻¹ in LIBs and 296 at 10 A g⁻¹ in SIBs), and prominent cycle life (553 after 2000 cycles at 5 A g⁻¹ in LIBs and 310 after 2000 cycles at 5 A g⁻¹ in SIBs). Such design conception can also provide guidance for the development of other high-performance electrodes. Full article

Developing microwave absorbers with superior low-frequency electromagnetic wave absorption properties is one of the foremost important factors driving the boom in 5G technology development. In this study, via a simple hydrothermal and pyrolysis strategy, randomly interleaved CoNiO₂ nanosheets and uniformly ultrafine CoNi nanocrystals are anchored onto both sides of a single-layered MXene. The absorption mechanism demonstrated that the hierarchical heterostructure prevents the aggregation of MXene nanoflakes and magnetic crystallites. In addition, the introduction of the double-magnetic phase of CoNiO₂/CoNi arrays can not only enhance the magnetic loss capacity but also generate larger void spaces and abundant heterogeneous interfaces, collectively promoting impedance-matching and furthering microwave attenuation capabilities at a low frequency. Hence, the reflection loss of the optimal absorber (M–MCNO) is −45.33 dB at 3.24 GHz, which corresponds to a matching thickness of 5.0 mm. Moreover, its EAB can entirely cover the S-band and C-band by tailoring the matching thickness from 2 to 7 mm. Satellite radar cross-section (RCS) simulations demonstrated that the M–MCNO can reduce the RCS value to below −10 dB m² over a multi-angle range. Thus, the proposed hybrid absorber is of great significance for the development of magnetized MXene composites with superior low-frequency microwave absorption properties. Full article

The rational design of a heterostructure electrocatalyst is an attractive strategy to produce hydrogen energy by electrochemical water splitting. Herein, we have constructed hierarchically structured architectures by immobilizing nickel–cobalt oxide nanowires on/beneath the surface of reduced graphene aerogels (NiCoO₂/rGAs) through solvent–thermal and activation treatments. The morphological structure of NiCoO₂/rGAs was characterized by microscopic analysis, and the porous structure not only accelerates the electrolyte ion diffusion but also prevents the agglomeration of NiCoO₂ nanowires, which is favorable to expose the large surface area and active sites. As further confirmed by the spectroscopic analysis, the tuned surface chemical state can boost the catalytic active sites to show the improved oxygen evolution reaction performance in alkaline electrolytes. Due to the synergistic effect of morphology and composition effect, NiCoO₂/rGAs show the overpotential of 258 mV at the current density of 10 mA cm⁻². Meanwhile, the small values of the Tafel slope and charge transfer resistance imply that NiCoO₂/rGAs own fast kinetic behavior during the OER test. The overlap of CV curves at the initial and 1001st cycles and almost no change in current density after the chronoamperometric (CA) test for 10 h confirm that NiCoO₂/rGAs own exceptional catalytic stability in a 1 M KOH electrolyte. This work provides a promising way to fabricate the hierarchically structured nanomaterials as efficient electrocatalysts for hydrogen production. Full article

New and efficient sensors of nerve agents are urgently demanded to prevent them from causing mass casualties in war or terrorist attacks. So, in this work, a novel hierarchical nanoheterostructure was synthesized via the direct growth of α-Fe₂O₃ nanorods onto multiwall carbon nanotube (MWCNT) backbones. Then, the composites were functionalized with hexafluoroisopropanol (HFIP) and successfully applied to detect dimethyl methylphosphonate (DMMP)-sarin simulant gas. The observations show that the HFIP-α-Fe₂O₃@MWCNT hybrids exhibit outstanding DMMP-sensing performance, including low operating temperature (220 °C), high response (6.0 to 0.1 ppm DMMP), short response/recovery time (8.7 s/11.9 s), as well as low detection limit (63.92 ppb). The analysis of the sensing mechanism demonstrates that the perfect sensing performance is mainly due to the synergistic effect of the chemical interaction of DMMP with the heterostructure and the physical adsorption of DMMP by hydrogen bonds with HFIP that are grafted on the α-Fe₂O₃@MWCNTs composite. The huge specific surface area of HFIP-α-Fe₂O₃@MWCNTs composite is also one of the reasons for this enhanced performance. This work not only offers a promising and effective method for synthesizing sensitive materials for high-performance gas sensors but also provides insight into the sensing mechanism of DMMP. Full article