Interfacial Junctions Research Articles

Dual Localized Surface Plasmon Resonance effect enhances Nb2AlC/Nb2C MXene thermally coupled photocatalytic reduction of CO2 hydrogenation activity

Nb2AlC/Nb2C MXene (NAC/NC) heterojunction photocatalysts with Schottky junctions were obtained by selective etching of the Al layer, resulting in 146.25 μmol·g−1 electrons and 15.28 μmol·g−1 holes stored in the heterojunction. The average conversion of NAC/NC thermally coupled photocatalytic reduction of CO2 under the simulated solar irradiation reached 110.15 μmol⋅g−1⋅h−1, and the CO selectivity reached over 92%, which was 1.49 and 1.74 times higher than that of pure Nb2AlC and Nb2C MXene, respectively. After light excitation, the localized surface plasmon resonance (LSPR) effect of holes distributed on the surface of Nb2C MXene crystals in the heterojunction will form high-energy thermal holes to dissociate H2 to H+ and reduce CO2 to form H2O at the same time. The high-energy electrons formed by the LSPR effect of Nb2C MXene and the conduction band electrons generated by the photoexcitation of Nb2C MXene can be migrated to Nb2AlC under the action of the interfacial Schottky junction to supplement the electrons needed for the LSPR effect of Nb2AlC, which continuously forms high-energy hot electrons to convert the adsorbed CO2 into *CO2−, b-HCO3, and HCOO. Subsequently, HCOO releases ⋅OH in a cyclic reaction to continuously reduce to form CO. The dual LSPR effect of Nb2AlC and Nb2C MXene is used to enhance the hydrogenation activity of thermally coupled photocatalytic reduction of CO2, which provides a new research idea for the application of MXene in thermally coupled photoreduction of CO2.

Construction of in-situ grid conductor skeleton and magnet core in biodegradable poly (butyleneadipate-co-terephthalate) for efficient electromagnetic interference shielding and low reflection

Conductive polymer composites have become an emerging electromagnetic interference (EMI) shielding material due to the advantages of light weight, corrosion resistance and low cost. However, low shielding efficiency, high reflectivity and non-biodegradability limit their applications in high-power devices, precision instruments and environmentally friendly fields. In this paper, poly (butyleneadipate-co-terephthalate) (PBAT) based EMI shielding composites with three-dimensional hybrid conductive networks as well as magnetic nanoparticles were prepared through the layer by layer coating and hot pressing. Regular PBAT microspheres were synthesized for the first time and used for isolated structure design. The interfacial junctions of the isolation units are composed of in situ synthesized polyaniline (PANI), as well as transition metal carbide (MXene) and CNTs that were adhered by PANI. The synergistic combination of these three conductive fillers promotes the construction of efficient shielding networks. The distribution of Fe3O4@MWCNT nanoparticles inside the PBAT matrix reduces the reflection of EM waves and weakens the EM radiation energy through magnetic loss. The shielding efficiency of the composites is up to 70.1 dB, and the percentage of reflected EM waves is as low as 26%. These biodegradable polymer-based EMI shielding composites with satisfactory shielding efficiency and low reflection function are expected to be widely used in the next generation of smart and environment-friendly electronic devices.

Fermi level induced band edge alignment and band bending in Ag3PO4/Cu2O p-n heterojunction for proficient photocatalytic applications

Fabrication of binary p-n heterojunction and the band alignment at the interface of the individual semiconductor photocatalyst has been extensively studied to verify superior charge separation and migration capability in photocatalytic applications. Here, a simple wet chemical followed by a hydrothermal fabrication strategy was introduced for the development of the binary p-n Ag3PO4/Cu2O heterostructures. The tunable band structure of individual semiconductors with the work function (φ), witnessed a band bending at the space charge region. The bending at the interface induces a carrier concentration gradient and manifests a rectifying current transport diode. The fabricated p-n heterostructures and carrier migration between n-type Ag3PO4 and p-type Cu2O were verified by different morphological and physicochemical methods. The band banding at the interface, leading to a narrow depletion region, favors the tunneling of electron-hole pairs through a Z-scheme carrier transport mechanism. The electron-hole pair movement has further been confirmed by considering the band edge position after contact, photocatalytic scavengers, and the radical trapping experiment. The Ag3PO4/Cu2O p-n heterojunction photocatalyst manifested a 737.4 μmol g−1h−1 of H2 generation and 91% endosulfan degradation efficiency, these are 12 and 9 times higher than that of pure Ag3PO4. The p-n heterojunction photocatalyst displayed a higher current density with electron-hole migration efficiency, synergistically enhancing the catalytic activity through the interfacial space charge junction.

Visible light active rGO nanosheet encapsulated Pd quantum-sized dots decorated TiO2 nano-spheres for hydrogen gas sensing at low temperatures

Making reliable gas sensors that function at low temperatures is important for safely detecting hydrogen gas. This work proposes sensitising reduced graphene oxide (rGO) nanosheet encapsulated TiO2 nano-spheres (TiO2-NS) with highly sensitive Pd receptors (rGPT-NS). It demonstrates for the first time, hydrogen gas sensing of rGPT-NS under 490 nm visible light conditions at low operating temperatures (25–35 °C) using a low voltage bias (0.1 V). The method suppresses of the electron-hole recombination and creating interfacial nano-Schottky junctions (i.e., heterojunctions) to enhance sensing performances. As a result, chemiresistive based highly responsive, selective, stable, environmentally friendly, and energy-efficient rGPT-NS are synthesised via sol-gel and hydrothermal methods. The fabricated sensing material exhibits high responses of 100.23%, 100.28% and 100.36% with rapid response/recovery (19 s/62 s, 12 s/57 s and 11 s/53 s) towards 500 ppm hydrogen at 25 °C, 30 °C and 35 °C, respectively under 0.1 V and 490 nm visible light.

α-Fe2O3/CeO2 S-scheme heterojunction photocatalyst for enhanced photocatalytic H2 evolution

High photo-stability and effective charge separation are pivotal for hydrogen production over the photocatalysts through solar energy. Here mesoporous CeO2 nanorods were hydrothermally synthesized using cetyltrimethyl ammonium bromide and tetrapropylammonium hydroxide as the template to construct the novel S-scheme heterojunction α-Fe2O3/CeO2 photocatalyst. The obtained heterojunction Fe2O3/CeO2 photocatalyst exhibited outstanding enhanced H2 evolution under visible illumination. The XRD results indicated that the Fe2O3/CeO2 nanocomposites revealed rhombohedral α-Fe2O3 and cubic CeO2 structures without impurities. TEM images revealed the formation of CeO2 nanorods with 400 nm length and 20 nm width decorated with Fe2O3 NPs (10 nm). The optimized S-scheme Fe2O3/CeO2 nanocomposites displayed a superior photocatalytic H2 evolution rate of 2973.2 µmolg−1h−1, which was promoted 5.43 folds greater than that of CeO2 nanorods (547.05 µmolg−1h−1). The electron transport channels in S-scheme Fe2O3/CeO2 nanocomposites interfacial junctions facilitated the directional migration spatial and separation of photocarriers. The H2 evolution rate over the obtained Fe2O3/CeO2 photocatalyst was significantly promoted due to its synergistic effect, porous architecture, oxygen vacancies, small particle size and high visible light absorption ability. There was no decrease in the H2 evolution rate after five cycles of photocatalytic H2 evolution, which could verify the durability and stability of the Fe2O3/CeO2 nanocomposite. The photoluminescence (PL) and electrophotochemical responses were conducted to determine the charge carriers separation rate and understand the photocatalytic mechanism.

Cu-MOFs based photocatalyst triggered antibacterial platform for wound healing: 2D/2D Schottky junction and DFT calculation

Herein, we developed a multimodal antibacterial nanoplatform via synergism effect including knife-effect, photothermal, photocatalytic induced reactive oxygen species (ROS), and Cu2+ inherent attribute. Typically, 0.8-TC/Cu-NS possesses higher photothermal property with the higher photothermal conversion efficiency of 24% and the moderate temperature up to 97 °C. Meanwhile, 0.8-TC/Cu-NS exhibits the more active ROS, 1O2 and ·O2-. Hence, 0.8-TC/Cu-NS possesses best antibacterial properties against S. aureus and E. coli in vitro with efficiency of 99.94%/99.97% under near-infrared (NIR) light, respectively. In the therapeutic practical use for wound healing of Kunming mice, this system exhibits outstanding curing capacity and good biocompatibility. Based on the electron configuration measurement and density functional theory (DFT) simulation, it is confirmed that the electrons on CB of Cu-TCPP flow fleetingly to MXene trough the interface, with redistribution of charge and band upward bending over Cu-TCPP. As a result, the self-assembled 2D/2D interfacial Schottky junction have made great favor to accelerate photogenerated charges mobility, hamper charge recombination, and increases the photothermal/photocatalytic activity. This work gives us a hint to mostly design the multimodal synergistic nanoplatform under NIR light in biological applications without drug resistance.

Enhanced hydrogen generation via overall water splitting using novel MoS2-BN nanoflowers assembled TiO2 ternary heterostructures

Envisaging headway in the applicability of sustainable H2 energy, the novel report of the fabrication of MoS2-BN/TiO2 (MBT) heterogeneous nanostructures has been proposed via facile in-situ hydrothermal route with an aim to propound the superior substitute of noble metal based conventionally employed catalytic system to surmount their exorbitant cost. We inferred the ascendancy of MoS2-BN nanoflowers over pristine MoS2 counterpart in an establishment of TiO2 based heterostructured catalysis. MBT heterostrucutres were extensively scrutinized with respect to their structural, optoelectronic and computational characteristics. En route to enhanced H2 evolution, we have investigated the significance of interfacial junctions and exposed sites in the MBT heterostructures. In order to achieve broader pertinence in green H2 fuel, the performance of MBT heterostrucutres was ascertained with subject to photochemical, electrochemical and photo-electrochemical (PEC) water splitting. Loaded concentration of MoS2-BN was varied in MBT catalysts and 2.5 wt% MoS2-BN/TiO2 exhibited optimum photocatalytic response with an H2 production rate of 2.6 mmol/g/h with 6.94% AQY and improved photo-current response of 0.99 mA/cm2 towards PEC. Electrochemical investigations further intensified the caliber of MBT as HER catalyst ascribed to the higher cathodic current density of 49.23 mA/cm2 at 1.22 V potential. The advancement in the catalytic efficiency of MBT heterostructures was evidenced by the synergetic relationship between MoS2-BN and TiO2 which stimulated the separation and transfer of photo-charged carriers, and lowered the overpotential values consequently surging the kinetics of H2 evolution.

Reduced Leakage Current and Enhanced Photovoltaic Effect in Zn-Doped BiFeO3 Thin Films

Zn-doped BiFeO3 (BFO) thin films with compositional formula BiFe1–xZnxO3 (x = 0, 0.1, and 0.2) have been epitaxially grown on SrRuO3 buffered SrTiO3 substrates by pulsed laser deposition. The high-concentration Zn doping does not suppress the ferroelectric polarization of the BFO films, and the Zn-doped BFO thin films also show reduced leakage current and an enhanced photovoltaic effect. By optical and photoelectron spectroscopy measurements, with Zn doping, the BFO thin films show more oxygen vacancies and a structural evolution, and moreover, a blue-shift of optical bandgap and an increase of work function are demonstrated. The reduction of leakage current and the enhancement of photovoltaic effect are related to the variation of interfacial Schottky junctions and oxygen vacancies with doping. This study reveals systematic insights into the effects of Zn doping on the physical properties of BFO thin films.

Visible light active Fe2O3/SnS heterojunction decorated with graphene oxide layer for improved photoelectrochemical performance

Tin monosulfide, also known as SnS, is a significant IV-VI group semiconductor that has acquired considerable emphasis owing to its good absorption in visible range. In the present work, nanostructured thin films of pure SnS, Fe2O3, and Fe2O3/SnS heterojunction were synthesized using cost effective thermal evaporation and Rf sputtering method, respectively. Furthermore, to enhance the sample's photoelectrochemical activity, a homogenous thin film of graphene oxide (GO) is coated on Fe2O3/SnS heterojunction sample. All samples were well characterized and their photoelectrochemical response was investigated. The maximum photocurrent density was observed for Fe2O3/SnS/GO heterojunction i.e. 1.0 ​mA/cm2 which is much higher than pure SnS (0.3 ​mA/cm2) and Fe2O3 (0.02 ​mA/cm2) at 0.95 ​V vs. Ag/AgCl. The role of graphene layer is being examined for the improved photoresponse. Remarkable photoresponse and stability of the Fe2O3/SnS/GO heterojunction sample may be attributed to better charge separation at the interfacial junction of SnS and Fe2O3 and excellent electron density of GO layer.

Unraveling the Role of Interface in Photogenerated Charge Separation at the Anatase/Rutile Heterophase Junction

Heterophase junctions have emerged as an effective strategy for spatial charge separation in photocatalysis. However, the photogenerated charge separation pathway at the junction region remains in doubt, and how the interfacial structure affects charge separation is unclear. Herein, we fabricate well-defined TiO2 heterophase junctions between rutile and anatase and employ in situ photochemical probing reactions to track the interfacial charges distribution by means of spherical aberration correction transmission electron microscope (CS aberration TEM). The photoreduction deposition of platinum (Pt) nanoclusters and photo-oxidation deposition of metal oxide nanoparticles demonstrate that the photogenerated electrons smoothly migrate across the interfacial phase junction from rutile to anatase phases and the photogenerated holes move in an opposite direction, which provides direct evidence on the spatial charge separation at the heterophase junction. Moreover, the atomic interfacial structure of anatase/rutile TiO2 heterophase junction formed is conducive for photogenerated charges moving from one phase to the other. This study revises the photogenerated charge separation at the anatase/rutile heterophase junction and demonstrates the important role of the interfacial structure on spatial charge separation.

CdS Nanoparticles Supported on Ti3C2Tx MXene for the Efficient Photocatalytic Production of H2O2: Implications for the Photocatalytic Degradation of Emerging Contaminants

Herein, Ti3C2Tx MXene was prepared and used to anchor CdS nanoparticles, and CdS/Ti3C2Tx (CT) photocatalyst with an interfacial Schottky junction was obtained for in situ hydrogen peroxide (H2O2) production to degrade emerging contaminants. CT-0.5 photocatalyst had the highest H2O2 production yield, which was 401 μmol L–1 within 1 h in pure water without organic sacrificial reagents under visible-light irradiation (λ > 420 nm), more than 3 times that of pristine CdS. The excellent photocatalytic performance was attributed to the unique properties of Ti3C2Tx and the formed Schottky junction, which accelerated electron transfer and spatial charge separation. The introduction of Ti3C2Tx improved the selectivity of two-electron O2 reduction, and the direct one-step two-electron O2 reduction route dominated the overall O2 reduction process for H2O2 production. Finally, CT-0.5 was applied to construct a photo-Fenton system, which also exhibited a superior catalytic performance and wide suitability for degrading emerging contaminants, suggesting its environmental significance.

Self-propelled nanojets an interfacial Schottky junctions modulated oxygen vacancies enriched for enhanced photo-Fenton degradation of organic contaminant: Improving H2O2 generation, Fe3+/Fe2+ cycle and enhancing plant metabolism

The study reports an innovative approach on sunlit driven heterostructure photocatalytic generation of H2O2 and removal of cefixime. In the present work, we have fabricated Mn/Mg doped CoFe2O4 modified CaCr2O4 decorated by Ag3PO4 quantum dots (Ag3PO4 QDs), a p-n-p nano heterojunction. The study promotes the photocatalytic production of H2O2 and self-Fenton photocatalytic degradation of cefixime. Egg white-assisted synthesis of Mn-doped CoFe2O4 causes the lattice oxygen defect, which enhances the photocatalytic activity. Lattice oxygen defect enable the adsorption of O2, which enable the conversion of •O2 in the valence band of CoFe2O4 for the endogenous production of H2O2. The higher in the surface area enhance the photocatalytic activity under visible light irradiation. Mn–CoFe2O4–CaCr2O4–Ag3PO4 QDs enables the complete photocatalytic degradation of cefixime (99.9%) and the complete removal was determined by total organic carbon (TOC) removal and it was around 99.4%. Meanwhile the photocatalytic degradation pathway of cefixime was determined by LC-MS/MS. Reusability of the nano heterojunction was determined by six cycle test, and the reusability of the nano heterojunction was 99.8%. Further, the toxicity of the nanomaterial was studied in maize plant and the results shows that the nanoheterojunction enhances the maize growth. The study systematically reveals the robust activity of nano heterojunction for sustainable water treatment.

NiS@CdS interfacial Schottky junction boosting spatial charge separation for highly efficient photocatalytic reduction of U(VI)

Effective uranium (U) removal from U-containing wastewater is pivotal to the sustainable development of the nuclear power industry. Photocatalysis is a promising technique and more effort is needed for designing more efficient photocatalysts. Here, NiS@CdS interfacial Schottky junction photocatalysts with different Ni/Cd molar ratios are synthesized. Under 90 min solar light irradiation, U(VI) removal efficiency from simulated U-containing wastewater is up to ∼99 %, and high recyclability after five cycles, 95.3 %, are obtained with Ni/Cd = 0.33 added for the synthesis. These are due to favorable Zeta potential and optical characteristics, narrow band gap and high stability of the composite. Besides, density functional theory (DFT) calculation illustrates the existence of interfacial Schottky junction between CdS and NiS, which may boost the spatial charge separation. Moreover, X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) characterizations show that U(VI) is successfully reduced to uraninite. This work potentially helps opening a new avenue for cost-effective U removal from U-containing wastewater.

Bias-Modified Schottky Barrier Height-Dependent Graphene/ReSe2 van der Waals Heterostructures for Excellent Photodetector and NO2 Gas Sensing Applications.

Herein, we reported a unique photo device consisting of monolayer graphene and a few-layer rhenium diselenide (ReSe2) heterojunction. The prepared Gr/ReSe2-HS demonstrated an excellent mobility of 380 cm2/Vs, current on/off ratio ~ 104, photoresponsivity (R ~ 74 AW-1 @ 82 mW cm-2), detectivity (D* ~ 1.25 × 1011 Jones), external quantum efficiency (EQE ~ 173%) and rapid photoresponse (rise/fall time ~ 75/3 µs) significantly higher to an individual ReSe2 device (mobility = 36 cm2 V-1s-1, Ion/Ioff ratio = 1.4 × 105-1.8 × 105, R = 11.2 AW-1, D* = 1.02 × 1010, EQE ~ 26.1%, rise/fall time = 2.37/5.03 s). Additionally, gate-bias dependent Schottky barrier height (SBH) estimation for individual ReSe2 (45 meV at Vbg = 40 V) and Gr/ReSe2-HS (9.02 meV at Vbg = 40 V) revealed a low value for the heterostructure, confirming dry transfer technique to be successful in fabricating an interfacial defects-free junction. In addition, HS is fully capable to demonstrate an excellent gas sensing response with rapid response/recovery time (39/126 s for NO2 at 200 ppb) and is operational at room temperature (26.85 °C). The proposed Gr/ReSe2-HS is capable of demonstrating excellent electro-optical, as well as gas sensing, performance simultaneously and, therefore, can be used as a building block to fabricate next-generation photodetectors and gas sensors.

Design of a Metal/Oxide/Carbon Interface for Highly Active and Selective Electrocatalysis.

Sustainable energy-conversion and chemical-production require catalysts with high activity, durability, and product-selectivity. Metal/oxide hybrid structure has been intensively investigated to achieve promising catalytic performance, especially in neutral or alkaline electrocatalysis where water dissociation is promoted near the oxide surface for (de)protonation of intermediates. Although catalytic promise of the hybrid structure is demonstrated, it is still challenging to precisely modulate metal/oxide interfacial interactions on the nanoscale. Herein, we report an effective strategy to construct rich metal/oxide nano-interfaces on conductive carbon supports in a surfactant-free and self-terminated way. When compared to the physically mixed Pd/CeO2 system, a much higher degree of interface formation was identified with largely improved hydrogen oxidation reaction (HOR) kinetics. The benefits of the rich metal-CeO2 interface were further generalized to Pd alloys for optimized adsorption energy, where the Pd3Ni/CeO2/C catalyst shows superior performance with HOR selectivity against CO poisoning and shows long-term stability. We believe this work highlights the importance of controlling the interfacial junctions of the electrocatalyst in simultaneously achieving enhanced activity, selectivity, and stability.

Chemically interconnected amorphous nanospheres SiOxCy as high performance anodes

Lithium battery, equipped with SiOx as anode, can deliver high discharge capacity, compared to conventional graphite anode. The application of SiOx in the lithium battery, however, is challenging due to its low conductivity and large volume expansion. In this study, a new sol-gel copolymerization route in free of toxic solvent is designed to synthesize interconnected amorphous SiOxCy (x∼1.5, 1.1≤y≤3.1) nanospheres. Both carbon and silica are chemically intertwined via Si-C and Si-O-C bonds, showing a homogeneous distribution throughout amorphous spheres at the atomic scale. These amorphous spheres are cemented through interfacial junctions, thereby forming the continuous electron transport passages. We discover that such amorphous spheres have a specific area of 16 m2/g, the lowest value currently reported. When used as lithium battery anode, chemically interconnected amorphous nanospheres show an excellent electrochemical performance, as represented by a reversible capacity as high as 697 mAh/g at a current density of 0.5 A/g after 500 cycles, which is superior to those ever reported in literature. The methodology reported here opens a potential avenue to develop chemically interconnected multi-component amorphous nanospheres with tunable chemical bonding states and conductive interfaces for different applications.

Electron-enriched Lewis acid-base sites on red carbon nitride for simultaneous hydrogen production and glucose isomerization

Glucose isomerization into fructose is a key process in industry for biomass valorization to produce value-added biofuels and biochemicals. Herein, considering the essential role of Lewis acid-base sites in proton transfer during glucose isomerization and hydrogen evolution process, a bifunctional polymeric red carbon nitride (PRCN) is rationally designed and fabricated by the salt-template-induced carbon incorporation strategy. The incorporation of carbon and potassium in the PRCN leads to the transient redistribution of photogenerated charges, acting as the electron-enriched Lewis base site and acid site for the deprotonation of O2-H and activation of aldehyde group of glucose, respectively. Besides, the interfacial Schottky junction boosts H2 production under visible light irradiation. This work demonstrates the feasibility of biomass photorefinery with H2 and value-added chemicals co-production under mild condition.

Photocatalytic and photo-electrochemical ammonia synthesis over dimensional oriented cobalt titanate/nitrogen-doped reduced graphene oxide junction interface catalyst

Nitrogen reduction to ammonia is vital for chemical industries and renewable clean energy. Denying the harsh reaction conditions adopted in the Haber-Bosch process and stimulation research for ammonia production through sustainable technologies is a smart approach. Hitherto, photocatalyst acquiring the potential to attain high nitrogen reduction reaction (NRR) efficiency is a challenging task. Here, this study demonstrated cobalt titanate (CoTiO3) rods (p-type) straddled with two-dimensional (2D) sheets of nitrogen-doped reduced graphene oxide (N-rGO, n-type) via, reflux method; realizing the advantages of dissimilar dimensionalities and strong interfacial junction coupling for efficient NRR under visible light irradiation. The successful interface junction establishment between CoTiO3 and N-rGO has been witnessed from Raman, x-ray photoelectron spectroscopy (XPS), and Mott-Schottky analysis. Moreover, a well-defined type-II band structure is capable to curl the charge anti-recombination process; reflected in upgraded photo-catalytic/electrocatalytic upshots. The CoTiO3 modified with an optimized concentration of N-rGO exhibits high stability with an improved photocatalytic (1722.22 μmolL-1h−1) and photo-electrocatalytic (16.8 µg cm-1h−1) nitrogen reduction to ammonia production; multiple times higher than counterparts. This improved photo-activity of CoTiO3/N-rGO junction hybrid stems from the built-in electric field existing across the dissimilar junction interface, triggering charge transfer channels for reduction reaction in mild reaction conditions. The result of these materials might strategies the way for future development of new functionalities bearing highly active catalyst materials for sustainable energy-related conversion.

Interfacial Schottky junctions modulated by photo-piezoelectric band bending to govern charge carrier migration for selective H2O2 generation

A major challenge faced by most systems is the dissociation of O−O bonding on H2O2 by subsequent electron (e-) reduction. This study investigates interfacial charge transfer by manipulating e- flows through a deflexed band potential on polarized piezoelectric BiFO3 (BFO). The H2O2 accumulation via coupling with the photocatalyst BiOCl/BiVO4 (BCV) was highly effective since the Schottky barrier height (SBH) formed within the heterojunction composite shifted according to the surface polarity of BFO. Additionally, the constant alternating surface charge on BFO, reduced the SBH, forcing the photoexcited e- to flow from BCV→BFO for effective H2O2 production, while restricting decomposition of H2O2 during downshifted band potential (positive surface) as high SBH discontinuing the electrons flow from BCV→BFO. The high interfacial charge transfer resistance (Rct) was also critical for H2O2 accumulation, since it is unfavorable for H2O2 dissociation (H2O2/·OH, +0.39 V) despite the presence of a high band potential (+0.16 eV) on the opposite surface's upshifted band. The formation rate (kf: 1.13 µmol L−1 min−1) of H2O2 was calculated much higher than decomposition rate (kd: 0.01 min−1). Additionally, the RRDE results indicated favorable 2e- transfer with > 90 % selectivity for H2O2. Results from ESR DMPO-·OH abduction and atrazine degradation show an insignificant concentration of ·OH has been produced. This work provides an effective strategy to regulate semiconductors' surface junction by piezoelectric polarization for selective H2O2 generation.

Rationally designed Ti3C2/N, S-TiO2/g-C3N4 ternary heterostructure with spatial charge separation for enhanced photocatalytic hydrogen evolution

The charge separation and transfer are the major issues dominating the under-laying energy conversion mechanism for photocatalytic system. Construction of semiconductor-based heterojunction system considered to be viable option for boosting the spatial charge separation and transfer in the photocatalytic water splitting system. Here, we design a ternary heterojunction of Ti3C2/N, S-TiO2/g-C3N4 by thermal annealing and ultrasonic assisted impregnation method having a well-designed n-n heterojunction and noble metal free Schottky junction for adequate hydrogen evolution. The optimal content of 4 wt% Ti3C2 on N, S-TiO2/g-C3N4 (4-TC/NST/CN) exhibit the highest rate of hydrogen generation 495.06μ mol h−1 which is 3.1, 4.1 and 1.6 fold higher than the pristine N, S doped-TiO2, g-C3N4 and binary hybrid (N, S doped-TiO2/g-C3N4) respectively, with 7% apparent conversion efficiency (ACE). The increment in the activity is described to the robust photogenerated carrier separation and double charge transfer channels because of the formation of dual heterojunction (n-n heterojunction and Schottky junction). XRD and Raman results revealed the occupancy of Ti3C2 in the heterojunction due to the strong interaction between Ti3C2, with N, S doped-TiO2 and g-C3N4. The HRTEM analysis confirmed the formation of close interfacial junction between the Ti3C2, N, S doped-TiO2 and g-C3N4. Moreover, the higher photocurrent, low PL intensity and lower impedance arc suggested the lower charge carrier recombination rate in 4-TC/NST/CN heterojunction. This work represents a significant development to establish a sound foundation for future design of MXene-based ternary hybrid system towards significant charge carrier separation and transfer for H2 production activity.