Intimate Interfacial Contact Research Articles

In-situ growth of few-layer graphene on ZnO with intimate interfacial contact for enhanced photocatalytic CO2 reduction activity

Intimate interfacial contact between semiconductor photocatalysts and cocatalysts is important for the transfer and separation of photogenerated charge carriers. Herein, few-layer graphene, as an efficient cocatalyst, was in-situ deposited on the surface of ZnO. The composite demonstrated improved photocatalytic CO2 reduction performance than pristine ZnO, ascribing to the intimate interfacial contact and Schottky junction between ZnO and graphene. Meanwhile, photothermal effect of graphene and π-π conjugation interaction between graphene and CO2 molecules also contributed to the performance enhancement. This work not only provides a feasible approach for the in-situ growth of graphene, but also develops an efficient photocatalyst for CO2 reduction.

In-situ growth of Ti3C2@MIL-NH2 composite for highly enhanced photocatalytic H2 evolution

The design and development of efficient metal–organic frameworks (MOFs) for photocatalytic H2 production from water have gained significant attention. However, the photocatalytic activity of MOFs is greatly limited by the poor conductivity. Herein, a Ti-based MOF (MIL-NH2) are in-situ grown onto layered Ti3C2 MXene, and the latter acts as the Ti source at the same time. The obtained composite (Ti3C2@MIL-NH2) displays superior H2 evolution performance with a rate as high as 4383.1 μmol h−1 g−1, which is much higher than the other MOF-based materials as far as we know. Combined analysis suggests that the Ti atom in Ti3C2 coordinates with the –NH2 group in MIL-NH2. This intimate interfacial contact is crucial for accelerating electron transfer and improving the photo-generated charge separation efficiency.

1D/1D Na2Ti3O7/SWCNTs electrode for split-cell-type asymmetric supercapacitor device

Hybrid storage systems require electrode materials with efficient capacitance and long cycle life. Their development is garnering increasing attention, with numerous efforts having been undertaken. Sodium titanate (Na2Ti3O7) has significant potential as an appropriate electrode material candidate for progressive energy storage. However, the application of Na2Ti3O7 is limited by its low electrical conductivity and cycling strength. Herein, a novel Na2Ti3O7/single-walled carbon nanotubes i.e NT/CNT nanostructure was fabricated via an in-situ hydrothermal method. Owing to the 1D/1D morphological features, high surface area, enriched interfacial conductivity, abundant active edge sites, and mesoporous nature of the Na2Ti3O7/SWCNTs nanostructure electrode, a remarkable capacity of 576.01 F g−1 at 0.8 A g−1 was obtained, with cycling stability featuring 91.43% retaining of capacitance after 5000 cycles. Importantly, a split-cell-type asymmetric supercapacitor was fabricated, demonstrating an energy density of 8.75 Wh kg−1 at a power density of 4500 W kg−1. A significant improvement in the electrochemical behavior of the novel 1D/1D NT/CNT nanostructure was primarily ascribed to the robust and intimate interfacial contact between the constituent Na2Ti3O7 and SWCNTs, acting as an optimal reservoir for electrolyte ions. These outcomes indicate that the NT/CNT nanostructure is a remarkable electrode material for electroactive energy storage devices.

2D/2D Nb3O7F/g-C3N4 Heterojunction Photocatalysts with Enhanced Hydrogen Evolution Activity

Constructing two-dimensional (2D)/2D heterojunctions with intimate interfacial contact is of great importance to achieve high photocatalytic efficiency for hydrogen evolution. Herein, 2D/2D niobium...

Constructing a 2D/2D interfacial contact in ReS2/TiO2via Ti–S bond for efficient charge transfer in photocatalytic hydrogen production

The 2D/2D intimate interfacial contact and short carrier transport distance were achieved by Ti–S bond in ReS2/TiO2. Dramatic photocatalytic hydrogen activity relies on the coexistence of homojunction and heterojunction.

Enhanced photocatalytic degradation of organic pollutants and hydrogen production by a visible light–responsive Bi2WO6/ZnIn2S4 heterojunction

In this work, we have reported the photocatalytic applications of the direct Z-scheme Bi2WO6/ZnIn2S4 heterojunction in the degradation of organic pollutants and the production of H2 gas. The nano-spherical shape of Bi2WO6 and porous structure of ZnIn2S4 particles, synthesized using cyclic microwave radiation method, facilitated the intimate interfacial contact of the heterojunction. Consequently, the photocatalytic activity of Bi2WO6/ZnIn2S4 towards degradation of salicylic acid (SA) and methylene blue (MB), the models of non-dye and dye organic pollutants, were maximized after introducing only 12.5%wt of Bi2WO6.Similarly, this photocatalyst demonstrated an enhancement in H2 production in comparison to the single-component photocatalysts. Furthermore, this photocatalyst maintained a high photoactivity after three repeated cycles for MB degradation and H2 production. The enhanced photo-efficacy of this heterojunction originates from the improved separation and transportation of photogenerated e−/h+ through a direct Z-scheme system. This was evidenced by electrochemical analyses and active species trapping experiments, combined with the consideration of reduction potential of reactive oxygen species.

TiO2@UiO‐66 Composites with Efficient Adsorption and Photocatalytic Oxidation of VOCs: Investigation of Synergistic Effects and Reaction Mechanism

AbstractTiO2@UiO‐66 composite with intimate contact interfaces is fabricated by in situ solvothermal methods. Compared with other UiO‐based composites, TiO2@UiO‐66 exhibits superior photocatalytic activity for oxidation of toluene into CO2 during long‐time reaction under flowing conditions. This is because (1) the intimate contact interface and well‐matched band structure between TiO2 and UiO‐66 can effectively separate and transfer photogenerated electrons; (2) the synergistic effect between UiO‐66 and TiO2 promotes the adsorption of toluene and desorption of CO2 and provides sufficient active sites for photocatalytic reaction. The toluene conversion and CO2 production on 4TiO2@U are 3.27 and 4.10 times higher than that on UiO‐66, respectively. 4TiO2@U also shows the highest activity for formaldehyde and rhodamine B degradations. The in situ FTIR results exhibit that toluene can be oxidized by .O2− and h+ to benzaldehyde and benzoic acid, then further oxidized to oxalic acid, and finally mineralized into CO2 and H2O.

Highly efficient tandem Z-scheme heterojunctions for visible light-based photocatalytic oxygen evolution reaction

Oxygen is important in maintaining a clean and reliable water environment. Designing heterojunction photocatalysts that can evolve oxygen from water splitting through an artificial Z-scheme pathway is a promising strategy for solving environmental problems. In this study, flower-like MoS2 nanostructures were fabricated via a simple hydrothermal process, and the electrostatic-based assembly ion-exchange method was used to construct a tandem Ag3PO4/MoS2/g-C3N4 (AMC) heterojunction. The as-synthesized photocatalyst exhibited significant improvements in harvesting visible light and transporting charge carriers. Moreover, the catalyst that was similar to the Z-scheme with intimate interface contact exhibited a strong oxygen evolution performance. The oxygen evolution activity of the optimal AMC-10 catalyst was approximately 11 times that of the pristine Ag3PO4. The results indicated that addition of a small amount of the flower-like MoS2 could significantly enhance the efficiency of oxygen evolution by the heterojunction. The findings in this study provide an alternative pathway for rationally designing efficient oxygen-evolving photocatalysts in order to improve the quality of water and rehabilitate the water environment.

MOF-Derived Mesoporous g-C3N4/TiO2 Heterojunction with Enhanced Photocatalytic Activity

Here, g-C3N4/TiO2 photocatalysts with mesoporous structure and intimate interfacial connection were synthesized via the facile pyrolysis of g-C3N4/MIL-125 composites. The photocatalytic H2 evolution reaction was performed to examine the photocatalytic activity of obtained photocatalysts. Under the UV–vis light irradiation, the average H2 evolution rate of g-C3N4/TiO2 sample with optimal g-C3N4 loading content (4.12wt%) was most increased by up to 0.606 mmol·g−1·h−1, a value which transcended that of as-prepared g-C3N4 (0.138 mmol·g−1·h−1) and mesoporous TiO2 (0.244 mmol·g−1·h−1) by a factor of 4.41 and 2.48, respectively. The improvement in photocatalytic activity of g-C3N4/TiO2 composites was explained by the synergistic effect between large specific surface area, decreased energy band gap and intimate interface contact. This study demonstrated a new approach for the preparation of binary mesoporous heterojunction photocatalysts.

Improving Cell Resistance and Cycle Life with Solvate/Thiophosphate Hybrid Electrolytes in Lithium Metal and Lithium Sulfur Batteries

Solid electrolytes (SEs) have become a practical option for lithium ion and lithium metal batteries due to their improved safety over commercially available ionic liquids. The most promising of the SEs are the thiophosphates whose excellent ionic conductivities at room temperature are comparable to those of the commercially-utilized ionic liquids. Hybrid solid-liquid electrolytes exhibit higher ionic conductivities than their bare solid electrolyte counterparts due to decreased grain boundary resistance, enhanced interfacial contact with electrodes, and decreased degradation at the interface.In this study, we evaluate a series of hybrid electrolytes made from a ‘solvate’ electrolyte in both Li-Li symmetric cells and in a full cell with a Li2S cathode relative to their bare Li/SE/Li counterparts. Interestingly, hybrid electrolytes made by combining HFE-modified solvates and SE exhibit all the benefits of the interlayer modified SEs, without the necessity of pellet manufacture. The solvate-integrated cathode layer is additionally beneficial for achieving high active material utilization, maintaining intimate interfacial contact, and providing buffer space for volume contraction and expansion. X-ray tomography measurements show the presence of a buffer layer results in substantially less crack formation. The hybrid Li2S cell exhibited superior cycling performance compared to the solid-state cells in terms of Li2S loading, Li2S utilization, and cycling stability. Finally, we discuss the use of hybrid electrolytes to enable other cathode chemistries.

Homogenously dispersed ultrasmall niobium(V) oxide nanoparticles enabling improved ionic conductivity and interfacial compatibility of composite polymer electrolyte

Composite polymer electrolytes (CPEs) decorated with ceramic fillers have emerged as appealing structures that exhibit coalesced merits of both inorganic and polymer solid electrolytes, but are currently challenged by the particle agglomeration that weakens ionic conductivity and electrochemical performances. Herein, a facile solvothermal method is proposed to fabricate the ultrasmall niobium(V) oxide (Nb2O5) nanoparticle of average size being less than 3 nm, enabling the composite polymer electrolyte with homogenous dispersity (nano-CPE). Owning to the superior dispersity of ultrasmall Nb2O5 nanoparticles, the polymer chains can be effectively disordered to enhance the local segmental motion through the physical interruption. Moreover, strong Lewis acid-based interactions between Nb2O5 nanoparticles and lithium salts are formed, resulting in accelerating the dissociation of lithium salt and releasing more free charge carriers. Therefore, the 3D connected Li+ fast pathways along the amorphous region between the Nb2O5 nanoparticles and polymer chains are constructed, ensuring the improved ionic conductivity. In addition, the homogenous Li deposition can also be simultaneously achieved through the intimate interfacial contact, which can efficiently suppress the growth of lithium dendrite in the metal anode. The fabricated nano-CPE presents a high ionic conductivity of 6.6 × 10−5 S/cm at room temperature and wide anti-oxidative potential of 5.1 V. The lithium symmetric battery using nano-CPE delivers a decent lithium plating/stripping performance for 200 h at 0.5 mA/cm2. The solid-sate LiFePO4 battery achieves long stable cycling performances (151mAh/g and 140 mAh/g after 230 cycles at 0.5C and 1.0C, respectively). This work may offer a facile and efficient synthesized method of highly dispersed ultrasmall nanoparticles for advancing the CPE with improved ionic conductivity, interfacial contact and cell performances.

Correlation of photocatalytic activity and defects generated in Ca2+-based heterojunctions

In this work a new semiconductor based on calcium heterojunction (CaO/CaTiO3) was evaluated to the optical properties correlated to crystalline lattice defects. The heterojunctions of the semiconductor were prepared by the sol–gel route and its formation was confirmed by the intimate contact interface between crystalline phases. Morphology and elemental composition of the nanometric heterojunction were evaluated. Chemical environment and composition of the surface were used to determine the oxidation state of the material constituents. The electronic structure was evaluated and the relationship among band gap energy, photoluminescent emission energy, and photocatalytic activity of the materials was demonstrated. Oxygen vacancies located on the surface promoted photoluminescent spectra emission in the green wavelength, making them more photoactive than those defects that emitted in the red region. The use of active species scavenger indicated that the photogenerated species with the greatest photocatalytic action was the superoxide radical. This study has developed calcium heterojunctions for application as photocatalysts, demonstrating the importance of the defects generated in the production of heterojunctions and the activity of photogenerated species, studied using scavengers.

Enriched oxygen vacancies of Cu2O/SnS2/SnO2 heterostructure for enhanced photocatalytic reduction of CO2 by water and nitrogen fixation

When two semiconductors are electronically coupled, their photocatalytic performance can be greatly enhanced. Herein, we formed a heterostructure between Cu2O and SnS2/SnO2 nanocomposite using a solvothermal reactor, which reduced CO2 by H2O at ambient conditions to produce CO, H2, and CH4. With inclusion of Cu2O, apparent quantum yield, a measure of photoactivity, has increased from 7.16% to 8.62%. Also, the selectivity of CH4 over CO was approximately 1.8-times higher than that of SnS2/SnO2. Interestingly, the as-synthesized catalysts were able to fix N2 to NH3 under light illumination at ambient conditions. Dissecting the mechanism into basic steps, it is shown that oxygen vacancies within the catalysts act as trapping sites for photo-induced charge carriers which strongly influenced the reactivity and selectivity of product. Additionally, oxygen vacancies act as active sites to chemisorb nitrogen molecules, which follow associative steps to generate NH3. In absence of sacrificial agent, the NH4+ generation rate was66.35μmol.g-1h-1 for Cu2O/SnS2/SnO2, which is 1.9-fold higher than SnS2/SnO2. Formation of a p-n heterojunction between Cu2O and SnS2/SnO2 nanocomposite offered favorable photoreductive potentials and high stability, mainly owing to their intimate interfacial contact. The results clearly illustrate a promising strategy to use oxygen vacancies rich heterostructure for wide application in photocatalysis.

Improved photocatalytic H2 evolution over composites based on niobium pentoxide, metal sulfides and graphene

The present research work focused on developing highly efficient visible light responsive photocatalyst for enhancement of hydrogen generation rate from water splitting. Effective heterostructure compositions were synthesized by the combination of Nb2O5–MoS2 (NM) with CdS/graphene and CuS/graphene (NM-CdS/G, NM-CuS/G) by using hydrothermal method. The crystallite sizes of the synthesized composites were inferred from X-ray diffraction (XRD) and found in the range 17–36 nm. The outcomes of scanning electron microscope (SEM) were confirmed the formation nano-structure by estimating particles sizes in the range 35–66 nm. This distinctive configuration exhibit enhanced light absorption, effectively develop the separation and transportation of photon-excited charge carriers and significantly raise photocatalytic hydrogen production rate. The energy band gap was reduced to 2.53 eV for NM-CdS/graphene composite. The prepared composite NM-CdS/graphene exhibited 100% degradation of MO in 180 min and the hydrogen generation rate was resulted about 8.7 mmol/h. The photo-generated electrons could efficiently migrate to the surface due to intimate interfacial contacts and synergism operating between NM and MS-Graphene (M = Cd, Cu) and the resulting improved separation potency of photo-induced electrons and holes inhibits the charge recombination rate and enhances photoactivity.

Boosting charge carriers separation and migration efficiency via fabricating all organic van der Waals heterojunction for efficient photoreduction of CO2

Two dimensional carbon nitride (2D CN) has attracted extensive attention due to its potential application in the field of photocatalysis. However, the poor electron-hole separation efficiency and low charge carrier migration speed confine the photocatalytic performance of 2D CN. In this work all organic van der Waals heterojunction (vdWH) catalyst (2D CN-COF) was prepared from 2D CN and triazine-based covalent organic framework (COF-TD) to efficiently enhance the catalytic activity of 2D CN. Characterization and simulation results verified the successful preparation of the catalyst. The heterojunction was originated from the intense interface van der Waals force interaction between the molecules of 2D CN and COF-TD. Furthermore, the intense π-π interaction between 2D CN and COF-TD led to the morphology transformation of COF-TD from sphere of isolated sample to elliptic sheet in 2D CN-COF. The intimate interface contact of vdWH has led to reduce bandgap, which remarkably enlarged the visible light responding region of the samples. Meanwhile, the charge carrier recombination was significantly reduced because of the formation of vdWH. The evolution rate of CO over 2D CN-COF was 9.2 times and 3.3 times higher than that of 2D CN and COF-TD, respectively. Moreover, the reaction was performed in the absence of any solvent and sacrificial agent, matching well with the idea of sustainable development. This work not only provides a new and simple strategy to fabricate 2D CN based all organic heterojunction catalyst for efficient photoreduction of CO2 to CO and CH4, but also serves as a reference for other researchers to design organic heterojunction, which is based on 2D CN and COFs.

High-gravity-assisted engineering of Ni2P/g-C3N4 nanocomposites with enhanced photocatalytic performance

Graphitic carbon nitride (g-C3N4) with transition metal phosphides has been studied extensively as potential photocatalysts for hydrogen evolution. However, in-situ approaches to realize intimate interfacial contacts have rarely been reported. In this study, Ni2P nanoparticles-decorated g-C3N4 photocatalysts were prepared via liquid exfoliation of g-C3N4 followed by in-situ loading of Ni2P nanoparticles in a rotating packed bed (RPB) reactor. The optimized Ni2P/g-C3N4 exhibits high performance in visible-light-driven (λ > 420 nm) hydrogen evolution (∼561 μmol g−1 h−1), which is 103 times higher than that of pristine g-C3N4. The superior photocatalytic performance and durability originate from the robust interfacial structure. Therefore, a Z-scheme route with enhanced transfer of photoinduced electron was proposed, and Ni2P/g-C3N4 composites with smaller bandgaps than those of g-C3N4 were realized. Due to the intensified mass transfer and mixing of RPB reactor, the adsorption and nucleation processes of Ni2P on g-C3N4 were enhanced, enabling scalable solar light-driven H2 production.

Well-defined FeP/CdS heterostructure construction with the assistance of amine for the efficient H2 evolution under visible light irradiation

The photocatalyst is a crucial factor in determining solar-to-H2 efficiency for solar-driven water splitting. Here, the FeP/CdS well-defined heterostructure was elaborately designed and successfully constructed in-situ to achieve efficient water splitting by using a simple and green solvothermal approach. In the synthetic process, the ethylenediamine plays an important role in the construction of intimate contact interface between FeP and CdS. This good quality FeP/CdS heterostructure can efficiently promote charge separation and transportation, and therefore the charge recombination of CdS was significantly suppressed. As a result, the as-synthesized FeP/CdS heterostructure showed excellent photocatalytic performance under visible-light irradiation with an optimal hydrogen evolution rate of 37.92 mmol g−1 h−1 and an apparent quantum yield of 31.50% at 420 nm far exceeding that of pristine CdS by more than 122 folds. This rate, to the best of our knowledge, outperforms other similar catalytic systems.

Facile construction of a fascinating Z-scheme AgI/Zn3V2O8 photocatalyst for the photocatalytic degradation of tetracycline under visible light irradiation

Solar-driven photocatalytic degradation undoubtedly represents a hopeful, sustainable together with effective alternative wastewater decontamination technology, however, exploiting highly efficient visible-light-induced photocatalysts for sewage remediation still exists a great challenge. Herein, a fascinating and unique AgI/Zn3V2O8 Z-scheme photocatalyst was rationally constructed by immobilizing AgI nanoparticles on the surface of flower-like Zn3V2O8 nanosheets using a facile precipitation approach. Multiple techniques were employed to uncover the structure, morphology, composition, optical and electrochemical properties of as-generated samples. As expected, the resultant AgI/Zn3V2O8 photocatalyst manifested greatly boosted the photocatalytic activity towards tetracycline (TC) degradation under visible light irradiation. Noticeably, the optimized AgI(20 wt%)/Zn3V2O8 photocatalyst displayed the largest removal efficiency of TC, which was around 2.1 and 2.5 folds higher than that of pristine Zn3V2O8 and AgI, separately. This improvement was due to the generated Z-scheme heterojunction between Zn3V2O8 and AgI with the intimate interfacial contact, which significantly promoting the spatial separation and migration efficiency of photoexcited charge carriers and maintaining the high redox potential at the same time. Furthermore, superoxide and hydroxyl radicals were identified as the main active species for TC degradation, and a possible degradation pathway of TC was also deduced. These findings may open a new avenue for reasonable design of high-efficiency Zn3V2O8-based Z-scheme heterojunction photocatalysts for the removal of antibiotics from wastewater.

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.

Boosting the visible-light photoelectrochemical performance of C3N4 by coupling with TiO2 and carbon nanotubes: An organic/inorganic hybrid photocatalyst nanocomposite for photoelectrochemical water spitting

Developing photoanode with proficient sunlight harvesting, stability as well as enhancing the electron injection across the interface remains a major challenge in the photoelectrochemical water splitting strategy to generate hydrogen. Herein, we design and fabricate an organic/inorganic TiO2/C3N4/CNT photoanode by a hydrothermal technique which exhibits much enhanced photoelectrochemical properties. The TiO2/C3N4/CNT photoanode exhibits a photocurrent density of 2.94 mA/cm2, which is ~6.4 time higher than pristine graphitic carbon nitride (C3N4) at an applied bias potential of 0.6 V vs. Ag/AgCl. The excellent photoelectrochemical performance benefits from the impactful migration of photo-induced electrons at the TiO2/C3N4 interface from C3N4 to TiO2 and their intimate interface contact with CNT. Kelvin probe force microscopy result shows a smaller interface barrier height (~10 meV) between TiO2 and C3N4, suggesting that electrons transport is favored through TiO2/C3N4 interfaces in a ternary photoanode. The TiO2/C3N4/CNT photoanode exhibited an onset potential of 0.25 V vs. Ag/AgCl which is much lower compared to pristine C3N4. The electrochemical impedance spectroscopy results also confirmed the enhanced electron injection across the interface in a ternary photoanode. These results demonstrate a promising approach to develop a highly proficient and visible light active photoanode with excellent stability for renewable energy applications.