Electron-hole Pairs Research Articles

CuO nanoflowers: Multifaceted implications of various precipitating agents on rectification behaviour

In order to achieve the best possible use of traditional energy resources for the preservation of the environment, semiconductor-based optoelectronic devices are one of the most intriguing methods for converting light energy into electrical energy. CuO has been extensively explored as a material for energy conversion and the development of photo-detectors due to its notable characteristics among other metals, especially its non-toxicity, abundance, high efficiency, electrochemical stability and low cost/promising photodiode. However, some drawbacks limit its practical application in white light and photo-detector, including the rapid recombination rate of photo-generated electron-hole pairs and destitute response to visible light. As a result, several strategies have been developed from an optoelectronics perspective to eradicate these deficiencies and make an effort to enhance CuO photodiode activities. In this research work, the electrical characteristics and rectification behaviour of CuO with various precipitating agents have been examined. The CuO nanoparticles can be synthesized by co-precipitation technique prepared with different precipitants. Through this research, several parameters, such as the structural, functional, morphological, optical and electrical characteristics, were investigated by changing the precipitants. The functional group formation of pure CuO phase was confirmed by FT-IR studies. UV–Vis absorption measurements indicate that the band gap of the CuO nanoparticles was ranging from 2.40 to 2.85 eV. As a diode, CuO/p-Si exhibits a non-ideal behaviour and under light conditions with Na2CO3 precipitant, the better ideality factor is about 2.35. The barrier height is determined by the thermionic emission theory to be 0.77 and 0.79 eV in the dark and light conditions respectively.

Coal-based carbon quantum dots modified Ni-MOF and Co/Zr-MOF heterojunctions for efficient photocatalytic hydrogen evolution

NS-CQDs were synthesized by a hydrothermal method using high-sulfur lignite as the carbon source. Modification of Ni-MOF and Co/Zr-MOF using NS-CQDs to explore the performance of composite photocatalysts for hydrogen production. It was found that NS-CQDs significantly enhanced the hydrogen precipitation performance of the composite photocatalysts compared with the MOFs catalysts alone, and the highest hydrogen precipitation rate of the novel composite photocatalyst 5%NS-CQDs/NCZ2 reached 3662.68 μmol g−1 h−1. It can be inferred from the conduction band and valence band positions of Ni-MOF, Co/Zr-MOF and NS-CQDs that a double S-type heterojunction is formed. The presence of thiophene and pyrrole nitrogen in NS-CQDs can promote electron transport, reduce the rate of electron-hole pair complexation, and improve the hydrogen evolution activity of the 5%NS-CQDs/NCZ2.

Enhanced optical and electrochemical properties of FeBTC MOF modified TiO2 photoanode for DSSCs application

In this work, iron based 1, 3, 5-tricarboxylic acid (FeBTC) was prepared via microwave-assisted method and incorporated into TiO2 via ultrasonic assisted method. The TiO2–FeBTC nanocomposites were characterized by XRD, FTIR, Raman, BET, FESEM, HRTEM, TGA, UV‒vis DRS and PL to understand their crystallographic, surface morphology, and optical characteristics. The Raman spectra showed a blue shift of Eg, A1g, and B1g peaks upon incorporation of FeBTC MOF onto TiO2. HRTEM and XRD analysis confirmed a mixture of TiO2 nanospheres and hexagonal FeBTC MOF morphologies with high crystallinity. The incorporation of FeBTC onto TiO2 improved the surface area as confirmed by BET results, which resulted in improved absorption in the visible region as a results of reduced bandgap energy from 3.2 to 2.84 eV. The PL results showed a reduced intensity for TiO2–FeBTC (6%) sample, indicating improved separation of electron hole pairs and reduced recombination rate. After fabrication of the TiO2–FeBTC MOF photoanode, the charge transfer kinetics were enhanced at TiO2–FeBTC MOF (6%) with Rp value of 966 Ω, as given by EIS studies. This led to high performance due to low charge resistance. Hence, high power conversion efficiency (PCE) value of 0.538% for TiO2–FeBTC (6%) was achieved, in comparison with other loadings. This was attributed to a relatively high surface area which allowed more charge shuttling and thus better electrical response. Conversely, upon increasing the FeBTC MOF loading to 8%, significant reduction in efficiency (0.478%) was obtained, which was attributed to sluggish charge transfer and fast electron–hole pair recombination rate. The TiO2–FeBTC (6%) may be a good candidate for use in DSSCs as a photoanode materials for improved efficiency.

Novel high entropy alloy/NiAl2O4 photocatalysts for the degradation of tetracycline hydrochloride: Heterojunction construction, performance evaluation and mechanistic insights

Novel NiAl2O4 (NAO)/high entropy alloy (HEA) (Ti), NAO/HEA (Mn) and NAO/HEA (Mo) heterojunction photocatalysts with high photocatalytic activity for the degradation of tetracycline hydrochloride (TC) under simulated sunlight irradiation were synthesized by the polyacrylamide gel method combined with a low temperature sintering technique. The effects of environmental parameters, including drug concentration, catalyst content and pH value, on the photocatalytic activity of NAO/HEA photocatalysts were investigated in detail on the basis of the response surface methodology (RSM) and experimental results. The optimal initial TC concentration, catalyst content, and pH were 100 mg/L, 1 g/L, and 5, respectively. The photocatalytic activity of NAO/HEA photocatalyst (84.6 %) was significantly improved compared to the degradation percentage of HEA (Ti) photocatalyst (36.5 %). The roles of active free radicals including h+, •O2−, •OH and oxygen vacancy in photocatalysis were verified using multiple characterization methods. In-depth analysis was conducted on the degradation pathway of TC, the safety of degradation intermediates, and the photocatalytic mechanism of NAO/HEA (Ti) photocatalyst. The Z - scheme heterojunction can significantly improve the transport efficiency of photogenerated carriers and inhibit the recombination rate of electron hole pairs in the system, which provides a new idea for exploring the application of new HEA - based heterojunction photocatalysts in the field of photocatalysis.

Modified metal–organic frameworks for sonophotocatalytic elimination of wastewater pollutants

In recent decades, people have witnessed a rapid development of society, accompanied by the increase sharply of numerous organic/inorganic contaminants from industrial effluents. The high toxicity of pollutants has led to long‐term risk to human health. To connect with environment‐friendly green chemistry and sustainable development, photocatalysis technology has emerged. Metal–organic framework (MOF)‐based photocatalysts performed high efficiency for the elimination of wastewater pollutants. Nevertheless, the large band gap energy and high recombination rate of photogenerated electron–hole pair decrease the catalytic efficiency. Sonochemistry is regarded as a safe, highly efficient, clean, and eco‐friendly technology, which has aroused a lot of interest in the treatment of wastewater. The cavitation effect induced by ultrasonic waves promotes the generation of additional active radicals. The ultrasonic oscillation facilitates cleaning the surface of catalysts, dispersing catalyst particles, and increasing proton transport. Therefore, photocatalysis coupling with ultrasonic waves, known as sonophotocatalysis (SPC), is a promising means for enhancing the overall performance of wastewater treatments. This review discusses the recent advancements of hybrid MOF‐based photocatalysts driving the wastewater treatments in SPC system. The catalytic performance of hybrid MOF is discussed in the SPC process. The inner properties of phases in hybrid MOF such as the location of redox potential and transfer direction of electrons and energy after hybridization are elucidated. Additionally, the review discusses the existing challenges and obstacles of MOF‐based SPC system and proposes feasible improvements to meet the future requirements of practical applications.

Photon-Dipole-Spin Interactions in M(TCNE)x/P(VDF-TrFE) Multiferroic Heterostructure Available for Bimodal Control of Multistate Data-Storage.

Organic multiferroic heterostructure is one of the most promising structures for the future design of high-density flexible energy-efficient data storage. Here, we fabricate organic ferromagnetic M(TCNE)x/ferroelectric P(VDF-TrFE) multiferroic heterostructures, where the excited state in M(TCNE)x interacted with localized dipole in P(VDF-TrFE) provides a key link for the interfacial coupling. Thus, aligned dipoles in P(VDF-TrFE) by external electric field can affect the magnetization of Fe(TCNE)x effectively to result in a pronounced magnetization-voltage (M-V) hysteresis loop. Moreover, light-induced electron-hole pairs in Fe(TCNE)x with long lifetime will effectively interact with the dipoles in P(VDF-TrFE) to lead to an effect in external light control of electric polarization of P(VDF-TrFE). Overall, the organic multiferroic heterostructure provides the possibility of realizing two storage modes, light control of dipole as well as electric field control of spin, which can broaden multifunctional applications of organic multiferroic materials in the area of multistate storage. This article is protected by copyright. All rights reserved.

Efficient Carrier Multiplication in Self-Powered Near-Ultraviolet γ-InSe/Graphene Heterostructure Photodetector with External Quantum Efficiency Exceeding 161.

Carrier multiplication (CM) in semiconductors, the process of absorbing a single high-energy photon to form two or more electron-hole pairs, offers great potential for the high-response detection of high-energy photons in the ultraviolet spectrum. However, compared to two-dimensional semiconductors, conventional bulk semiconductors not only face integration and flexibility bottlenecks but also exhibit inferior CM performance. To attain efficient CM for ultraviolet detection, we designed a two-terminal photodetector featuring a unilateral Schottky junction based on a two-dimensional γ-InSe/graphene heterostructure. Benefiting from a strong built-in electric field, the photogenerated high-energy electrons in γ-InSe, an ideal ultraviolet light-absorbing layer, can efficiently transfer to graphene without cooling. It results in efficient CM within the graphene, yielding an ultrahigh responsivity of 468 mA/W and a record-high external quantum efficiency of 161.2% when it is exposed to 360 nm light at zero bias. This work provides valuable insights into developing next-generation ultraviolet photodetectors with high performance and low-power consumption.

Dual Polarization Strategy for Boosting Electron-Hole Separation toward Overall Water Splitting within Ferroelectric β-AIBIIIO2 (BIII = P3+, As3+, Sb3+, and Bi3+ for Lone Pairs).

Ferroelectric materials, leveraging an inherent built-in electric field, are excellent in suppressing electron-hole recombination. However, the reliance solely on bulk polarization remains insufficient in enhancing carriers' separation and migration, limiting their practical application in photocatalytic overall water splitting (POWS). To address this, we incorporated cations with ns2 lone pairs (P3+, As3+, Sb3+, and Bi3+) into ferroelectric semiconductors, successfully constructing 44 β-AIBIIIO2 photocatalysts with dual polarization. Through rigorous first-principles calculations and screenings for stability, band characteristics, and polarization, we identified four promising candidates: β-LiSbO2, β-NaSbO2, β-LiBiO2, and β-TlBiO2. Within these materials, lone pairs induce local polarization in the xy-plane. Additionally, out of the plane, there is robust bulk polarization along the z-direction. This synergistic effect of the combined local and bulk polarization significantly improves the separation efficiency of electron-hole pairs. Explicitly, the electron mobility of the four candidates ranges from 105 to 106 cm2 s-1 V-1, while the hole mobility also increases significantly compared to single-phase polarized materials, up to 106 cm2 s-1 V-1. Notably, β-TlBiO2 is predicted to achieve a solar-to-hydrogen (STH) efficiency of 17.2%. This study not only offers insights for water-splitting catalyst screening but also pioneers a path for electron-hole separation through the dual polarization strategy.

Piezoelectric Polarization and Sulfur Vacancy Enhanced Photocatalytic Hydrogen Evolution Performance of Bi2S3/ZnSn(OH)6 Piezo-photocatalyst.

The combination of piezoelectric catalysis and photocatalysis could effectively enhance the carrier separation efficiency and further improve the hydrogen production activity. However, piezoelectric polarization always suffers from a low polarization strength, which severely restricts its actual applications. In this study, we successfully synthesized a novel sulfur vacancy-rich Bi2S3/ZnSn (OH)6 (BS-12/ZSH) piezo-photocatalyst for hydrogen evolution through water splitting. Notably, the piezo-photocatalytic hydrogen generation rate of the 8% BS-12/ZSH catalyst (336.21 μmol/g/h) was superior to that of pristine ZSH (29.71 μmol/g/h) and BS-12 (21.66 μmol/g/h). In addition, the hydrogen generation for 8% BS-12/ZSH (336.21 μmol/g/h) under ultrasonic coupling illumination was significantly higher than that under single illumination (52.09 μmol/g/h) and ultrasound (121.90 μmol/g/h), owing to the cooperative interaction of the sulfur vacancy and piezoelectric field. Various characterization analyses confirmed that (1) the introduction of sulfur vacancies in BS-12 provided more active sites, (2) BS-12 with sulfur vacancies acted as a co-catalyst to accelerate the hydrogen production rate, and (3) the piezoelectric field eliminated the electrostatic shielding and offered an additional driving force, which effectively promoted the separation of electron-hole pairs. This research clearly reveals the synergistic effect between piezocatalysis and photocatalysis as well as offers a promising sight for the rational design of high-efficiency piezo-photocatalysts.

Rapid Hydrolysis Precipitation of BiOBr Nanosheets for Boosting Photocatalytic N2 Fixation

AbstractIn this paper, BiOBr nanosheets were synthesized through a novel hydrolysis precipitation method, which significantly reduced energy consumption and time cost compared to traditional hydrothermal synthesis methods. The subjected hydrothermal and high‐temperature calcination process promote the generation of surface oxygen vacancies, which inhibited the recombination of photogenerated electron hole pairs and improve the photocatalytic performance of BiOBr. Additionally, by adjusting the addition amount of KOH in the synthesis process, BiOBr can grow towards more complex crystal structure, which also provides a new path for the fabrication of 2D materials.

In Situ Photodeposition of Gold Nanoparticles with Exposed High-Activity Crystal Facets under Different Sacrificial Agents.

In situ photodeposition presents a powerful approach for integrating noble metal co-catalysts onto semiconductor surfaces. However, achieving precise control over the microstructure of the deposited co-catalyst remains a major challenge. Au nanoparticles (NPs) are deposited onto H-KCNO using HAuCl4 in the presence of various sacrificial agents in this study. Notably, the choice of sacrificial agent decisively influences the exposed crystal facets, loaded content, and particle size of the deposited Au NPs. Importantly, in situ photodeposition under an ethanol solution facilitates the exposure of the highly active (111) and (220) crystal facets of Au. The introduction of Au NPs significantly enhances photocatalytic hydrogen evolution, achieving rates of 4.93, 57.88, and 15.44 μmol/h for H-KCNO/Au-(water, ethanol, and lactic acid), respectively. The observed photocatalytic activity for hydrogen evolution indicates that the exposure of the highly active planes emerges as critical for significant performance enhancement. Photoelectrochemical and photoluminescence measurements suggest that the highly active (111) and (220) crystal facets effectively segregate sites for redox reactions, thereby impeding the recombination of photogenerated electron-hole pairs.

Microwave-Assisted Synthesis of SnO2@ZnIn2S4 Composites for Highly Efficient Photocatalytic Hydrogen Evolution.

This research successfully synthesized SnO2@ZnIn2S4 composites for photocatalytic tap water splitting using a rapid two-step microwave-assisted synthesis method. This study investigated the impact of incorporating a fixed quantity of SnO2 nanoparticles and combining them with various materials to form composites, aiming to enhance photocatalytic hydrogen production. Additionally, different weights of SnO2 nanoparticles were added to the ZnIn2S4 reaction precursor to prepare SnO2@ZnIn2S4 composites for photocatalytic hydrogen production. Notably, the photocatalytic efficiency of SnO2@ZnIn2S4 composites is substantially higher than that of pure SnO2 nanoparticles and ZnIn2S4 nanosheets: 17.9-fold and 6.3-fold, respectively. The enhancement is credited to the successful use of visible light and the facilitation of electron transfer across the heterojunction, leading to the efficient dissociation of electron-hole pairs. Additionally, evaluations of recyclability demonstrated the remarkable longevity of SnO2@ZnIn2S4 composites, maintaining high levels of photocatalytic hydrogen production over eight cycles without significant efficiency loss, indicating their impressive durability. This investigation presents a promising strategy for crafting and producing environmentally sustainable SnO2@ZnIn2S4 composites with prospective implementations in photocatalytic hydrogen generation.

Regulation of Lewis acid sites on ZnO/SiW11Co for tunable photocatalytic activity toward water remediation

The function of surface acidity in catalytic reactions has been well studied in the field of conventional catalysis, nevertheless, regulating surface acidic sites and unveiling its roles during heterogeneous photocatalysis has been less frequently reported. To address this issue, we constructed a novel heterojunction photocatalyst of ZnO/SiW11Co with abundant Lewis acid sites for wastewater treatment. Under visible light irradiation, the optimal ZnO/SiW11Co was found to have the highest photocatalytic activity, achieving a degradation efficiency of 97.7% for Rhodamine B (RhB), 96.1% for tetracycline (TC), and 91.4% for methyl orange (MO). The RhB removal rate remained at 91.3% even after five cycles, indicating excellent stability and practicality of ZnO/SiW11Co. By compositing with SiW11Co, a typical polyoxometalates with unique super acid properties, ZnO/SiW11Co formed plentiful surface Lewis acid sites, as confirmed by the pyridine adsorption FT-IR and NH3-TPD. The as-formed Lewis acid sites could provide more active sites, making it easier for reactants to coordinate to the photocatalyst surface, which reduced the activation energy of photocatalytic reactions and accelerate RhB removal. Density functional theory (DFT) calculations unveiled the redistribution of electron-hole pairs, optimizing the light absorption and charge separation efficiency, which obeyed a Z-scheme mechanism. Combined active species capture experiments and electron spin resonance, •O2−, h+, and •OH were the main active substances for the photocatalytic degradation of RhB. Besides, the possible degradation pathways for RhB were analyzed using liquid chromatography-mass spectrometry (LC-MS). The work provided useful strategy for the design of high-performance photocatalysts via regulating surface Lewis acid sites toward water remediation.

Perovskite Nanocrystals In Situ Encapsulated in TiO2 Microspheres for Stable CO2 Photoreduction in Water.

Photoreduction of carbon dioxide (CO2) into fuels presents a promising approach to mitigate global warming and energy crises. Halide perovskite nanocrystals (NCs) with prominent optoelectronic properties have triggered substantial attention as photocatalysts but are limited by the charge recombination and instability. Here, we develop stable CsPbBr3/titania microspheres (TMs) by in situ growth of CsPbBr3 NCs inside mesoporous TMs through solid-state sintering, which significantly improves the stability of perovskite NCs, making them applicable in water with efficient CO2 photoreduction performance. Notably, the CsPbBr3/TMs demonstrates a 6.73- and 9.23-fold increase in the rate of CH4 production compared to TMs and CsPbBr3, respectively. The internal electric field facilitates S-scheme charge transfer, enhancing the separation of electron-hole pairs, as evidenced by X-ray photoelectron spectroscopy and electron paramagnetic resonance analysis, which is pivotal for the selective photoreduction of CO2. These insights pave the way for the design of CsPbBr3-based photocatalysts with superior efficiency and stability.

High-performance self-biased Cu/SiC/Si photo-sensor with swift response for NIR/Vis photodetection

Silicon Carbide (SiC) shows great potential for use in high temperatures and harsh environments due to its promising physical properties. This report introduces a novel double depletion functional heterointerface comprising a multilayer structure of Cu/SiC/Si. High-quality nanocrystalline SiC thin films are fabricated on p-type Silicon (Si) by RF magnetron sputtering at a relatively low temperature of 900 °C as compared to conventional methods. A multilayer photo-sensor device, comprising Cu/SiC/Si layers, is fabricated through the thermal evaporation of Cu metal using a shadow mask. The device exhibits good photo-response at both 750 nm and 440 nm wavelengths. Both the junctions Cu/SiC and SiC/Si play role in generating electron-hole pairs along the depth of the device. The device exhibits a very high responsivity of 1.26 A/W and a rapid response of 94/137 ms at a wavelength of 750 nm at self-bias conditions. It also demonstrates a high responsivity of 0.46 A/W and a very fast response time of 66.8/66.4 ms for 440 nm wavelength. Owing to its impressive performance, this device distinguishes itself as a superior choice among state-of-the-art SiC-based photodetectors. Its significance lies in the robust stability of the SiC/Si junction in high-temperature settings, surpassing low bandgap materials for NIR/vis photodetectors.

Lattice strain engineered reactive oxygen species generation of NaNbO3 ferroelectric

The generation of reactive oxygen species (ROS) using ambient mechanical energy with piezoelectric materials is emerging as a promising method for producing renewable green oxidants. However, the low piezoelectricity and limited electron-hole pair separation efficiency significantly hinder its productivity. Here, non-stoichiometric Na1-xNbO3-δ perovskites with lattice strain and ferroelectric enhancement were successfully designed to boost the piezo-catalytic activity. Significantly, hydrogen peroxide (H2O2), superoxide radicals (•O2-), and hydroxyl radicals (•OH) were powerfully generated by the Na0.95NbO2.975 piezo-catalyst through redox reaction with rates of 362.4, 69.3, and 65.0 µmol∙g-1∙h-1, respectively, and the yield of H2O2 was approximately three times higher than that of the stoichiometric NaNbO3. The elevated piezoelectricity and polarization electric field effects induced by lattice strain could promote the generation of electron-hole pairs and drive them to separate facilely. The distribution of sodium vacancies and oxygen vacancies in the crystal lattice enhanced the diffusion of carriers for fast migration to the opposite surface of the catalyst. Furthermore, the presence of Na defects enhanced the adsorption of O2 on the Na1-xNbO3-δ surface and contributed to the catalytic generation of H2O2. This work provides a novel and effective methodology for the design of high-performance piezo-catalysts with lattice-strained engineering and broadens the strategy for improved H2O2 evolution efficiency.

BiVO4-based heterojunction nanophotocatalysts for water splitting and organic pollutant degradation: a comprehensive review of photocatalytic innovation

Abstract The novel semiconductor photocatalytic material bismuth vanadate (BiVO4) is gaining significant attention in research due to its unique characteristics, which include a low band gap, good responsiveness to visible light, and non-toxic nature. However, intrinsic constraints such as poor photogenerated charge transfer, slow water oxidation kinetics, and fast electron–hole pair recombination limit the photocatalytic activity of BiVO4. Building heterojunctions has shown to be an effective strategy for enhancing charge separation and impeding electron–hole pair recombination over the last few decades. This review covers the state-of-the-art developments in heterojunction nanomaterials based on BiVO4 for photocatalysis. It explores heterojunction design, clarifies reaction mechanisms, and highlights the current developments in applications including photocatalytic water splitting and organic matter degradation. Finally, it offers a preview of the development paths and opportunities for BiVO4-based heterojunction nanomaterials in the future. This comprehensive assessment of BiVO4-based heterojunctions provides insightful knowledge to researchers in materials science, chemistry, and environmental engineering that will drive advances and breakthroughs in these important fields.

Construction of Bi2WO6/g-C3N4/Cu foam as 3D Z-scheme photocatalyst for photocatalytic CO2 reduction

Photocatalytic CO2 reduction to hydrocarbon fuels represents a promising solution to CO2 emission challenges. However, photocatalytic CO2 reduction systems face hurdles in practical utilization for the low efficiency of photocatalysts and challenge in catalyst immobilization. Therefore, a novel monolithic three-dimensional Z-scheme photocatalyst was synthesized by fabricating Bi2WO6/g-C3N4 heterojunction on Cu foam substrate (Bi2WO6/g-C3N4/Cu foam) via thermal polymerization and electrophoresis deposition. A series of characterization results, including X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and N2 adsorption–desorption, illustrate the crystalline properties, pore structure, and morphology of the composite photocatalyst. Consequently, Bi2WO6/g-C3N4/Cu foam achieved CO production yield of 33.84 μmol/g cat under visible light illumination for 6 h and retained 96.2 % of initial photocatalytic activity after 30 h of reaction. UV–Vis diffuse reflection spectra, photoluminescence spectra and photoelectrochemical analysis was involved to reveal the mechanism of the photocatalytic activity of composite photocatalyst.The synergistic effect of the Z-scheme mechanism and the hierarchical macroporous structure improves the light absorption, light-induced electron-hole pair separation, and charge transmission. This catalyst construction strategy provides a viable approach for facilitating practical photocatalytic CO2 reduction.

Interlayer Potassium Single-Atom-Coordinated g-C3N4 for Significantly Boosted Visible Light Photocatalytic H2 Production.

In recent years, graphitic carbon nitride (g-C3N4) has attracted considerable attention because it includes earth-abundant carbon and nitrogen elements and exhibits good chemical and thermal stability owing to the strong covalent interaction in its conjugated layer structure. However, bulk g-C3N4 has some disadvantages of low specific surface area, poor light absorption, rapid recombination of photogenerated charge carriers, and insufficient active sites, which hinder its practical applications. In this study, we design and synthesize potassium single-atom (K SAs)-doped g-C3N4 porous nanosheets (CM-KX, where X represents the mass of KHP added) via supramolecular self-assembling and chemical cross-linking copolymerization strategies. The results show that the utilization of supramolecules as precursors can produce g-C3N4 nanosheets with reduced thickness, increased surface area, and abundant mesopores. In addition, the intercalation of K atoms within the g-C3N4 nitrogen pots through the formation of K-N bonds results in the reduction of the band gap and expansion of the visible-light absorption range. The optimized K-doped CM-K12 nanosheets achieve a specific surface area of 127 m2 g-1, which is 11.4 times larger than that of the pristine g-C3N4 nanosheets. Furthermore, the optimal CM-K12 sample exhibits the maximum H2 production rate of 127.78 μmol h-1 under visible light (λ ≥ 420 nm), which is nearly 23 times higher than that of bare g-C3N4. This significant improvement of photocatalytic activity is attributed to the synergistic effects of the mesoporous structure and K SAs doping, which effectively increase the specific surface area, improve the visible-light absorption capacity, and facilitate the separation and transfer of photogenerated electron-hole pairs. Besides, the optimal sample shows good chemical stability for 20 h in the recycling experiments. Density functional theory calculations confirm that the introduction of K SAs significantly boosts the adsorption energy for water and decreases the activation energy barrier for the reduction of water to hydrogen.

Ternary heterostructure-driven photoinduced electron-hole separation enhanced oxidative stress for triple-negative breast cancer therapy

Zinc oxide nanoparticles (ZnO NPs) stand as among the most significant metal oxide nanoparticles in trigger the formation of reactive oxygen species (ROS) and induce apoptosis. Nevertheless, the utilization of ZnO NPs has been limited by the shallowness of short-wavelength light and the constrained production of ROS. To overcome these limitations, a strategy involves achieving a red shift towards the near-infrared (NIR) light spectrum, promoting the separation and restraining the recombination of electron-hole (e−-h+) pairs. Herein, the hybrid plasmonic system Au@ZnO (AZ) with graphene quantum dots (GQDs) doping (AZG) nano heterostructures is rationally designed for optimal NIR-driven cancer treatment. Significantly, a multifold increase in ROS generation can be achieved through the following creative initiatives: (i) plasmonic Au nanorods expands the photocatalytic capabilities of AZG into the NIR domain, offering a foundation for NIR-induced ROS generation for clinical utilization; (ii) elaborate design of mesoporous core-shell AZ structures facilitates the redistribution of electron-hole pairs; (iii) the incorporation GQDs in mesoporous structure could efficiently restrain the recombination of the e−-h+ pairs; (iv) Modification of hyaluronic acid (HA) can enhance CD44 receptor mediated targeted triple-negative breast cancer (TNBC). In addition, the introduced Au NRs present as catalysts for enhancing photothermal therapy (PTT), effectively inducing apoptosis in tumor cells. The resulting HA-modified AZG (AZGH) exhibits efficient hot electron injection and e−-h+ separation, affording unparalleled convenience for ROS production and enabling NIR-induced PDT for the cancer treanment. As a result, our well-designed mesoporous core-shell AZGH hybrid as photosensitizers can exhibit excellent PDT efficacy.