Efficient Electron-hole Separation Research Articles

Self-powered γ-In2Se3/p-Si heterojunction for photodetection: exploring humidity and light intensity dependent photoresponse

In this study, high-quality γ-In2Se3 thin films were successfully deposited on p-Si substrates via the RF sputtering technique. Structural characterization using XRD and Raman spectroscopy confirmed the formation of the hexagonal γ-phase of In2Se3 film. FESEM analysis revealed the presence of small, homogeneous, and well-defined grains in the prepared γ-In2Se3 film. EDS analysis confirmed the stoichiometric composition (∼ 2:3) of the In2Se3 films. XPS further validated the presence of In, Se, and Si elements in the deposited films. Band gap analysis using UV-visible spectroscopy yielded a value of 1.96 eV for the γ-In2Se3 film. Integration of γ-In2Se3 with p-type Si enhanced photoresponsivity of 47.9 mA/W, photosensitivity of 282, and photo detectivity of 8.45 × 1010 Jones. The self-powered γ-In2Se3/p-Si heterojunction-based photodetector exhibited rapid rise time attributed to the type II band alignment structure, facilitating efficient electron-hole pair separation and minimizing recombination. Furthermore, humidity and light intensity-dependent photodetector properties of γ-In2Se3/p-Si heterojunction photodetector were also investigated. An increase in photocurrent from 271 to 291 µA was observed with rising humidity levels, indicating the device’s sensitivity to humidity variations. Furthermore, light intensity dependence studies revealed a linear relationship between photocurrent and incident light intensity, demonstrating the device’s reliable response across various illumination levels.

Microwave-Assisted Synthesis of CdS-MOF MIL-101 (Fe) Composite: Characterization and Photocatalytic Performance.

The present study outlines the synthesis of cadmium sulfide-metal-organic framework (CdS-MOF) MIL-101 (Fe) heterojunctions achieved via fast microwave-assisted reactions. Thus, different CdS-MOF MIL-101 (Fe) ratios were prepared to study their effectiveness as photocatalysts. These compounds were employed in the photocatalytic degradation of methylene blue (MB) under UV and visible irradiation. Structural, morphological, textural, compositional, and optical properties of the synthesized compounds determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize the structural, morphological, textural, compositional, and optical properties. Electrochemical impedance spectroscopy (EIS) was also employed to determine photovoltage and photocurrent densities. The resulting valence band offset (Vfb) and band gap energy values were utilized to construct an energy band scheme. Our research revealed that the CdS-MOF MIL-101 (Fe) heterojunction enhances the efficiency of electron-hole pair separation, thereby mitigating charge carrier recombination effects. Moreover, the type I electronic band structure established an efficient reaction mechanism, effectively suppressing the recombination of photogenerated electron-hole pairs. The photocatalytic system demonstrated exceptional behavior, achieving complete MB removal within 30 min of reaction time and exhibiting outstanding stability and reusability after four reaction cycles. These findings highlight the potential of the synthesized compounds in the field of wastewater treatment for organic pollutants, offering a promising alternative to current environmental issues.

Water/oil interfacial photocatalysis of amphiphilic CdS/Bi2WO6 S-scheme heterojunctions for efficient production and spontaneous separation of H2O2 and value-added organics

The photocatalytic co-production of H2O2 and value-added organics in a suitable water/oil biphasic system offers an intriguing strategy to address the challenges encountered in a single liquid-phase solution, including the efficient separation of H2O2 and organic products as well as the mitigation of undesirable secondary reactions. For this, exploring amphiphilic photocatalysts with high performance is highly required. Herein, an amphiphilic CdS/Bi2WO6 S-scheme heterojunction photocatalyst is designedly synthesized through a two-step solvothermal process, aiming to achieve efficient interfacial photocatalytic reactions at the water/oil interface for simultaneous generation and selective separation of H2O2 and organic products. The CdS/Bi2WO6 heterojunction photocatalyst exhibits enhanced light absorption in UV-visible region, increased electron-hole separation efficiency, and powerful charge carriers with high redox abilities. Moreover, the formation of S-scheme heterojunction improves the catalyst stability by preventing CdS from photocorrosion. As a result, the production rate of H2O2 reaches up to 216.76mmolg-1 h-1, accompanied by the generation of organic products (benzaldehyde: 104.91mmolg-1 h-1, benzoic acid: 49.88mmolg-1 h-1, and benzyl benzoate: 38.01mmolg-1 h-1), in a water/benzyl-alcohol biphasic system under simulated sunlight irradiation. The photocatalytic mechanism is elucidated based on the results of comprehensive experiments and characterizations. This study highlights a rational construction of amphiphilic photocatalysts and their application in organic/water interfacial photocatalytic reactions.

Visible light assisted periodate activation with porous C3N5 for tetracycline degradation: Enhanced electron-hole separation and reactive oxygen species formation

In this study, porous C3N5 (p-C3N5) was synthesized to activate periodate (PI) for tetracycline (TC) degradation under visible light condition. Experimental results confirmed that the porous structure in C3N5 created abundant defects as active sites, which not only increased the photoelectricity and electron-hole separation efficiency, but also promoted PI activation and reactive oxygen species formation, achieving significantly improved PI-assisted photocatalytic performance. In detail, p-C3N5 exhibited high photocurrent density which was 12.7 and 28.9 times as much as those of g-C3N5 and g-C3N4 respectively. Moreover, the p-C3N5/PI/vis system can achieve 80% TC removal rate within 10 min via ∙O2-, 1O2, IO3∙, ∙OH, h+ and electron transfer pathways. Furthermore, this system could maintain stable degradation capacity under a wide pH range, with less interference by inorganic anions, demonstrating its high reusability, robustness and environmental friendliness. Six possible degradation pathways of TC were proposed based on the detection of intermediate products and density functional theory calculation. Finally, the toxicity assessment showed a significantly reduction of TC bio-toxicity after treatment by p-C3N5/PI/vis system, and no formation of iodine by-products. It provides a deep insight into designing high efficiency and environmentally photocatalysts for activating PI to treat the antibiotic wastewater.

Microenvironment modulation of Fe-porphyrinic metal–organic frameworks for CO2 photoreduction

Photocatalytic CO2 reduction to fuels and chemicals is a promising pathway towards carbon resource recovery. Herein, three isomorphic Fe-porphyrinic MOFs, Zr6O4(OH)4(Fe-TCPP)3 (MOF-525, Fe-TCPP = iron 5,10,15,20-tetra(4-carboxyphenyl)-porphyrin), Zr6O4(OH)4(Fe-TCPP-NO2)3 (MOF-525-NO2, Fe-TCPP-NO2 = iron 5,10,15,20-tetra(2-nitro-4-carboxyphenyl)-porphyrin), and Zr6O4(OH)4(Fe-TCBPP-NO2)3 (MOF-526-NO2, Fe-TCBPP-NO2 = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)-2-nitrophenyl]-porphyrin) were synthesized and employed as photocatalysts for CO2 reduction. Among them, MOF-525-NO2 exhibited the highest catalytic activity with CO and H2 yields of 10.36 and 0.46 mmol·g−1 without any photosensitizer under visible light. Mechanism investigations suggested that the micro-environments of these MOFs were adjusted by introducing porphyrinic fragments with different lengths and functional groups, resulting in stronger CO2 affinity, faster photocurrent response, and efficient photogenerated electron-hole separation and transfer, which finally promoted the efficiency for photocatalytic CO2 reduction.

Unprecedented Photocatalytic Hydrogen Peroxide Production via Covalent Triazine Frameworks Constructed from Fused Building Blocks.

Covalent organic frameworks (COFs) have garnered attention for their potential in photocatalytic hydrogen peroxide (H2O2) production. However, their photocatalytic efficiency is impeded by insufficient exciton dissociation and charge carrier transport. Constructing COFs with superior planarity is an effective way to enhance the π-conjugation degree and facilitate electron-hole separation. Nonetheless, the conventional linear linkers of COFs inevitably introduce torsional strain that disrupts coplanarity.Herein, we address this issue by introducing inherently coplanar triazine rings as linkers and fused building blocks as monomers to create covalent triazine frameworks (fused CTFs) with superior coplanarity. Both experimental and theoretical calculations confirm that CTFs constructed from fused building blocks significantly enhance the electron-hole separation efficiency and improve the photocatalytic performance, compared to the CTFs constructed with non-fused building blocks. The frontier molecular orbitals and electrostatic potentials (ESP) revealed that the ORR is preferentially facilitated by the triazine rings, with the WOR likely occurring at the thiophene-containing moiety. Remarkably, CTF-BTT achieved an exceptional H2O2 production rate of 74956 μmol g-1 h-1 when employing 10% benzyl alcohol (V/V) as a sacrificial agent in an O2-saturated atmosphere, surpassing existing photocatalysts by nearly an order of magnitude.

The n-MoO3/p-Si heterojunction photodiode: Influence of the MoO3 film thickness on the ultraviolet and infrared photodetector performance

Here, we studied the effect of the MoO3 thin film thickness on the ultraviolet (UV) and infrared (IR) photodiode properties of the n-MoO3/p-Si heterojunction structure. Initially, the metal molybdenum (Mo) thin films with different thicknesses (50,150, and 250 nm) were created via DC magnetron sputtering on a p-type Si substrate. Then, the MoO3 thin films were synthesized using a thermal oxidation method with an optimal oxygen flow rate of 60sccm. XRD and Raman analysis showed that the structure of prepared thin films has converted from an amorphous to an orthorhombic (α-MoO3) crystalline phase with increasing thickness. The optical transmittance of the layers was tuned by controlling the thickness, and the maximum transmittance for the 50 nm-thick film was achieved in the broad wavelength range of 300–1100 nm. The current density–voltage (J–V) characteristics indicate the prepared samples' rectifying behavior under dark conditions. The heterojunction photodiode with a 50 nm-thick MoO3 layer shows the best performance. This sample had a maximum amount of transmittance in the UV–visible and IR regions, compared to other samples, which leads to efficient electron-hole separation and transportation. This sample demonstrates a significant photoresponse ratio (ILight/IDark) of about 55 and 52.5 in the ultraviolet (UV) and infrared (IR) regions, respectively.

1D Lead Bromide Hybrids Directed by Complex Cations: Syntheses, Structures, Optical and Photocatalytic Properties.

This study presents the synthesis, structural characterization, and evaluation of the photocatalytic performance of two novel one-dimensional (1D) lead(II) bromide hybrids, [Co(2,2'-bpy)3][Pb2Br6CH3OH] (1) and [Fe(2,2'-bpy)3][Pb2Br6] (2), synthesized via solvothermal reactions. These compounds incorporate transition metal complex cations as structural directors, contributing to the unique photophysical and photocatalytic properties of the resulting materials. Single-crystal X-ray diffraction analysis reveals that both compounds crystallize in monoclinic space groups with distinct 1D lead bromide chain configurations influenced by the nature of the complex cations. Optical property assessments show band gaps of 3.04 eV and 2.02 eV for compounds 1 and 2, respectively, indicating their potential for visible light absorption. Photocurrent measurements indicate a significantly higher electron-hole separation efficiency in compound 2, correlated with its narrower band gap. Additionally, photocatalytic evaluations demonstrate that while both compounds degrade organic dyes effectively, compound 2 also exhibits notable hydrogen evolution activity under visible light, a property not observed in 1. These findings highlight the role of metal complex cations in tuning the electronic and structural properties of lead(II) bromide hybrids, enhancing their applicability in photocatalytic and optoelectronic devices.

Construction of SnO2/Cu2O heterojunctions for enhanced photocatalytic degradation of moxifloxacin

Herein, SnO2/Cu2O heterojunction composites were prepared using a hydrothermal method for moxifloxacin removal from water. Cu2O and SnO2 were detected in the composite samples, which exhibited between the two semiconductors. The introduction of SnO2 into pure Cu2O, forming a heterojunction structure, can enhance device charge conversion, improve photocurrent intensity and photogenerated electron-hole separation efficiency, and greatly improve photocatalytic performance. Moxifloxacin degradation by SnO2/Cu2O composites reached 86.4%. The proposed catalytic mechanism was based on radical scavenging, with • identified as the main active species. In addition, the moxifloxacin degradation intermediates were analyzed, with possible degradation pathways suggested.

Unveiling the Synergistic Role of Ferroelectric Polarization and Z‐Scheme Heterojunction in Bi2Fe4O9/Carbon‐Deficient g‐C3N4 for Enhanced Methylene Blue Degradation Efficiency

ABSTRACTEnhancing the efficiency of charge carrier separation is crucial for improving the performance of photocatalysts, thereby offering more effective solutions to energy and environmental pollution challenges. In this study, a carbon‐deficient ultra‐thin porous g‐C3N4 (Vc‐UPCN) was synthesized and subsequently was integrated with Bi2Fe4O9 (BFO) using a sonochemical self‐assembly technique, a Bi2Fe4O9/Vc‐UPCN (BC) photocatalyst featuring a Z‐scheme heterojunction. The BC catalyst was subjected to corona poling treatment to obtain BCp, which possesses an intrinsic electric field. Compared with pure BFO and Vc‐UPCN, the BC heterojunction exhibited higher photo‐generated electron–hole separation efficiency and photodegradation ability. Upon introduction of corona polarization, the photocatalytic performance of BC was further enhanced. Specifically, BCp‐15 (BFO/BC mass fraction = 15) achieved complete degradation of methylene blue (MB) within 30 min. BCp‐15 demonstrated that its degradation efficiency for MB was 1.28 times higher than that of BC‐15, 1.85 times higher than that of Vc‐UPCN, and impressive 7.69 times higher than that of pure BFO. The coupling effect of the heterojunction and ferroelectric polarization significantly improved the separation efficiency of photo‐generated carriers in BCp. This study is expected to provide a reference for the synergistic application of heterojunction and ferroelectric polarization in traditional semiconductor photocatalysis.

Reduced Ag NPs-modified NaTaO3 layer improves photocatalytic degradation and antimicrobial ability through LSPR effect and doping behavior

Reduced Ag NPs modified Ag-doped NaTaO3 layer photocatalysts were prepared using the hydrothermal method. The research investigated the microstructure and degradation ability of composite layer containing Ag-NaTaO3. Various techniques, including SEM,TEM, XRD, UV–Vis and PL analyses, were used for the evaluation. The antibacterial effect of the Ag-NaTaO3 layers on Staphylococcus aureus (S. aureus) before and after modification with reduced Ag NPs was evaluated. The Ag-NaTaO3 composite layer showed stronger degradation effect and bactericidal activity than NaTaO3 under the optimal conditions (Concentration of Ag+-containing solution 0.1 mol/L, reaction temperature 200 ℃, reaction time 3 h). The degradation efficiency of Ag3-NaTaO3 for MB was 87.6 % after 50 min, and the bactericidal inhibition rate was 100 % after 20 min. The degradation process, with electron hole (h+) as the main active substance, conforms to the first-order kinetic with a rate constant (K) value of 0.0310 min−1. The band gaps (Eg) of the calculated pure phase NaTaO3 and Ag3-NaTaO3 are 3.18 eV and 2.75 eV, correspondingly. The fluorescence decay spectra indicate that the average expected lifetimes of Ag3-NaTaO3 composites rounded is 11.45 ns, respectively. The NaTaO3 nano-cubic structure, prepared using Ta2O5 precursor, reduces the grain size, provides more surface active sites, and effectively improves the range of the NaTaO3 photoresponse. AgNO3 solution is used to reduce Ag NPs and carry out doping behavior. The LSPR behavior of Ag NPs and the doping behavior of Ag lower the Schottky barrier that is made up of the metal–semiconductor interface. This ensures that the hot metal electrons are injected into the semiconductors efficiently, improves the electron-hole (h+) separation efficiency, and enhances the photocatalytic activity. The bacterial structure was destroyed through a dual mechanism of reactive oxygen species (ROS) (·OH, ·O2–) and Ag properties, achieving excellent bacterial inhibition. This study proposes a new concept to enhance the photocatalytic performance of NaTaO3 thinfilm materials, which will could have significant applications in the field of wastewater treatment.

Investigation of different ratio of CuCe catalysts applied in photothermal reverse water gas shift reaction

The photothermal catalytic reverse water gas shift reaction (RWGS) can convert CO2 into other high-value-added chemical resources under mild conditions. However, the design and development of high-performance catalysts is a major challenge. In this work, different proportions of CuCe bimetallic catalysts were synthesized using the sol-gel method and applied to RWGS. Under the visible light heat catalytic condition at 450 ℃, the CO yield can be increased by about 20 % compared to thermal catalysis, which is better than most metal-based catalysts reported in the literature. Moreover, the catalyst exhibited good stability and reusability, with the primary factor affecting the stability of the CuCe catalyst being the growth of Cu nanoparticles. The characterization shows that at Cu/Ce=1, the separation efficiency of electron-hole separation is the highest, and the hot electrons generated by the LSPR effect of Cu can be effectively separated and transferred, producing more oxygen vacancies and suitable alkaline sites, so it has the best photothermal catalytic performance. Furthermore, the catalyst is dominated by the formate pathway under light conditions, and this work provides a new RWGS strategy.

Construction of AgI/NH2-MIL-125(Ti) heterojunction: Efficient degradation of organic pollutants in water by visible light response

Photocatalytic technology is an effective means to convert clean solar energy into green chemical energy, which has broad application prospects. Metal-organic framework (MOFs) composites have been widely used to remove pollutants from water. In this paper, the photocatalytic effect of NH2-MIL-125(Ti)[NM125(Ti)] photocatalyst with different AgI content on pollutants in water under visible light irradiation were studied. The successful preparation of AgI/NH2-MIL-125(Ti) photocatalyst was proved by the characterization of the physical and chemical structure of the composite material. When the dosage of AgI is 0.5 mmol, the removal rate of TC by AgI/NH2-MIL-125(Ti) is the highest (82 %). In addition, the photoelectrochemical test also proved that AMNT-0.5 mmol photocatalyst has higher electron-hole separation efficiency. After five cycle tests, the composite photocatalyst of ANMT-0.5 mmol still has good stability. The enhancement of the performance of ANMT-0.5 mmol photocatalyst can be attributed to: (i) the introduction of AgI increases the absorption of visible light in the composite; (ii) The close relationship between AgI and NM125(Ti) accelerates the separation of electron-hole pairs, thus improving the photocatalytic performance.

Recycling of UO22+ expanded by metal-organic framework bearing pyrazinoquinoxaline tetracarboxylic acid: pH fluorescence sensing and photocatalytic activity

With the wide application of nuclear energy, the recycling of uranium resources and environmental protection have become the focus of scientific research and industrial attention. Uranyl ions have better electronic configurations and optical properties, but poor energy utilization and recycling as ionic states. Drawing on the structural features of Metal-Organic Frameworks (MOFs), the combination of UO22+ nodes with photoactive ligands should be able to effectively regulate the energy level matching between metal nodes and conjugated ligands, improve the electronic configuration and energy band structure, and thus produce better photoresponsive functional properties. In the present work, an example of a novel two-dimensional layered U-MOF was constructed by self-assembly, which utilizes pyrazinoquinoxaline tetracarboxylic acid. Due to the stable coordination structure, matched energy levels and synergistic photoresponsive behavior of UO22+ with pyrazinoquinoxaline ligands, U-MOF enables fluorescence sensing response in aqueous solution at pH=2–5, 9.5–12 and fluorescence quenching detection of a wide range of substrates. Theoretical calculations reveal that the interaction of the hydrogen ion with pyrazinozinoquinoxaline moiety extends the degree of conjugation of the moiety. Meanwhile, the interaction of hydroxide ions with pyrazinozinoquinoxaline groups elevates the highest occupied molecular orbital (HOMO) energy level, which significantly affects the photoelectric properties of U-MOF. In addition, U-MOF can be used as a photocatalyst to realize the conversion of benzylamine to N-benzylbenzylideneimine by oxidation under mild conditions. The effective electron transfer between uranyl ions and ligands ensured the photogenerated electron-hole separation efficiency and enhanced the energy utilization. Therefore, the related results of U-MOFs illustrate the practicality of introducing UO22+ nodes into MOFs to construct novel photoresponsive materials, which provides a new way for the efficient recycling and utilization of uranium resources.

Synergistic effects of CQDs and oxygen vacancies on CeO2 photocatalyst for efficient photocatalytic nitrogen fixation

The combination of carbon quantum dots (CQDs) with oxygen vacancies (OVs) provides a promising approach to achieving efficient photocatalytic nitrogen fixation. It was by a hydrothermal method that CQDs-modified CeO2 composites (CQDs/CeO2) were synthesized. The synergistic effects of CQDs and OVs on CeO2 photocatalyst enhanced interfacial electron transfer capabilities, thus the photocatalytic nitrogen fixation was significantly enhanced. CQDs/CeO2 exhibited the most superior efficiency in photocatalytic nitrogen fixation, reaching 826 μmol·g−1·h−1, when the addition of CQDs was 200 µL. It was the introduction of CQDs that effectively regulated the concentration of OVs. OVs captured the electrons, thus promoting electron transfer. This enhancement not only improved the electron-hole separation efficiency in CQDs/CeO2 but also greatly promoted the adsorption and activation of N2 by OVs. This work offered a novel strategy for designing efficient photocatalysts for nitrogen fixation.

(Co, S)-Codoped BiOBr as a novel signal probe coupled with LAMP (H+)-pH responsive photoelectrochemistry biosensor for ultrasensitive detection of microRNA

Herein, Co/S-BiOBr as a novel photoelectric material with excellent photoelectric property was prepared by cation–anion co-doping method with LAMP (H+)-pH responsive as signal amplification to construct a photochemical (PEC) biosensor for ultrasensitive detection of microRNA-221 (miRNA-221) related to triple-negative breast cancer (TNBC). Notably, not only the lattice distortion caused by S doping could elevate the photo-generated electron-hole separation efficiency, but also the tune of electronic structure by Co doping promoted electron transfer and decreased recombination rate, thus significantly improving the photoelectric performance. Furthermore, in the aid of Loop-mediated isothermal amplification (LAMP), a few miRNA-221 could be converted to abundant LAMP(H+) for changing the configuration of the Fc-DNA probe, which made the ferrocene (Fc) approach to electrode via pH-responsive for hindering the transmission of electrons, resulting in a significantly reduced photocurrent signal to enhance the sensitivity of the biosensor. The proposed PEC biosensor performed a wide range from 1 fM to 10 nM with a detection limit of 0.24 fM. This work prepared a novel material with efficient photoelectric efficiency for sensitive detection of biomolecules and exhibited enormous potential in disease diagnosis.

Self-Assembly Regulated Photocatalysis of Porphyrin-TiO2 Nanocomposites.

Photoactive artificial nanocatalysts that mimic natural photoenergy systems can yield clean and renewable energy. However, their poor photoabsorption capability and disfavored photogenic electron-hole recombination hinder their production. Herein, we designed two nanocatalysts with various microstructures by combining the tailored self-assembly of the meso-tetra(p-hydroxyphenyl) porphine photosensitizer with the growth of titanium dioxide (TiO2). The porphyrin photoabsorption antenna efficiently extended the absorption range of TiO2 in the visible region, while anatase TiO2 promoted the efficient electron-hole separation of porphyrin. The photo-induced electrons were transferred to the surface of the Pt co-catalyst for the generation of hydrogen via water splitting, and the hole was utilized for the decomposition of methyl orange dye. The hybrid structure showed greatly increased photocatalytic performance compared to the core@shell structure due to massive active sites and increased photo-generated electron output. This controlled assembly regulation provides a new approach for the fabrication of advanced, structure-dependent photocatalysts.

Cu-Fe bimetallic MOFs with long lifetime separated-state charge for enhancing selectivity for CO2 photoreduction to CH4

Improving the CO2 to CH4 conversion efficiency of Cu metal-organic frameworks (Cu-MOFs) catalysts is important for promoting carbon capture and utilization. In this work, a series of novel Cu-Fe bimetallic MOFs photocatalysts (Cu-BTB-Fe with 0.5 wt%, 1.0 wt%, 2.0 wt%, and 4.0 wt% of Fe; H3BTB = 1,3,5-tris(4-carboxyphenyl) benzene) were synthesized by a bimetallic site (Cu and Fe) design strategy in order to improve the electron-hole separation efficiency and CO2 adsorption activation. Findings indicated that the as-synthesized Cu-BTB-2 wt% Fe catalyst exhibited excellent catalytic performance for the conversion of CO2 to CH4 and CO under simulated sunlight irradiation, providing a yield of 32.20 μmol∙g−1∙h−1 and a selectivity of 69.24 % for CO2 to CH4 conversion as well as a yield of 14.29 μmol∙g−1∙h−1 for CO2 to CO conversion without liquid phase products. This is because the Cu-Fe bimetallic sites can continuously supply photoinduced electrons with long separated-state decay lifetime to efficiently activate CO2. Specifically, the Cu-BTB-Fe catalysts provided a high proportion of effective photoinduced electrons with long decay lifetime for the CO* hydrogenation process through a unique electron transfer mechanism, while the strong affinity between CO2 and [Cu2(COO)4]-Fe active units enabled high CO2 adsorption activation and rapid CO2 reduction. The present approach, hopefully, would help to establish feasible pathway for the development of novel highly selective Cu-based MOFs photocatalysts for CO2 photocatalytic reduction yielding CH4.

ZnIn2S4 nanostructure grown on electronegative h-BN for highly efficient photocatalytic hydrogen evolution

The photo-corrosion issue inherent in metal sulfide semiconductors is quite pronounced, making the enhancement of electron-hole pair separation efficiency in these photocatalysts a pivotal strategy for boosting photocatalytic hydrogen production. This study introduces a novel approach where hexagonal boron nitride (h-BN) acts as a substrate for the in situ growth of ZnIn2S4 nanostructures, resulting in the formation of h-BN@ZnIn2S4 (BN@ZIS) nanocomposites. The electronegativity of h-BN nanosheets is harnessed to facilitate the recombination or electrostatic attraction of photogenerated holes in the ZnIn2S4 photocatalyst. This strategy effectively promotes the separation of photogenerated electron-hole pairs, which is crucial for enhancing photocatalytic performance. The microstructure, morphology and optical properties of BN@ZIS nanocomposites were meticulously investigated. The findings reveal that the incorporation of h-BN nanosheets loads to a more uniform dispersion of the ZnIn2S4 nanostructure, which not only increases the specific surface area but also fosters a tight heterojunction interface between h-BN and ZnIn2S4. In conclusion, the photocatalytic hydrogen production capabilities of the BN@ZIS nanocomposites were rigorously evaluated. Pure h-BN lacks photocatalytic hydrogen production activity. Conversely, the optimized BN@ZIS composite demonstrated a remarkable enhancement, exhibiting a photocatalytic efficiency that is 9.65 times greater than that of pristine ZnIn2S4. Furthermore, a plausible mechanism by which BN@ZIS augments photocatalytic hydrogen production has been proposed. This strategy, leveraging the synergistic interaction between h-BN and ZnIn2S4, is anticipated to be applicable to other semiconductor systems, opening avenues for the advancement of photocatalytic technologies.

Acousto-Drag Photovoltaic Effect by Piezoelectric Integration of Two-Dimensional Semiconductors.

Light-to-electricity conversion is crucial for energy harvesting and photodetection, requiring efficient electron-hole pair separation to prevent recombination. Traditional junction-based mechanisms using built-in electric fields fail in nonbarrier regions. Homogeneous material harvesting under a photovoltaic effect is appealing but is only realized in noncentrosymmetric systems via a bulk photovoltaic effect. Here we report the realization of a photovoltaic effect by employing surface acoustic waves (SAWs) to generate zero-bias photocurrent in the conventional layered semiconductor MoSe2. SAWs induce periodic modulation to electronic bands and drag the photoexcited pairs toward the traveling direction. The photocurrent is extracted from a local barrier. The separation of generation and extraction processes suppresses recombination and yields a large nonlocal photoresponse. We distinguish the acousto-electric drag and electron-hole pair separation effect by fabricating devices of different configurations. The acousto-drag photovoltaic effect, enabled by piezoelectric integration, offers an efficient light-to-electricity conversion method, independent of semiconductor crystal symmetry.