Photogenerated Holes Research Articles

Ultrafast hole transfer mediated by a conjugated self-assembled molecule enables efficient and stable wide-bandgap perovskite solar cells

Charge accumulations and electron recombination at the interfaces between perovskites and charge transporting materials are two critical factors significantly hindering the power conversion efficiency (PCE) and device stability of wide-bandgap perovskite solar cells (WBG PSCs). Herein, we tailor-made a self-assembled molecule (SAM), termed XS13, featuring an enlarged π-donor and a π-linker, to regulate the interface carrier dynamics in ∼1.8 eV WBG PSCs. Ultrafast spectroscopy clearly demonstrated that the XS13 facilitated the rapid extraction and transfer of photo-generated holes compared to the reference SAM-2PACz. Consequently, WBG PSCs based on XS13 achieved an outstanding PCE of up to 19.20 %, surpassing that of control devices (16.41 %). Furthermore, XS13-based WBG PSCs exhibited a remarkable suppression of light/electricity-induced halide ions migration, leading to significantly improved device stability. Our findings offer a new strategy for the rational design of hole transporting molecules with controlled properties to enhance device performance of PSCs.

(Invited) Photocatalysis of Mg-Doped SrTiO3 for Conversion of CO2 with H2O

Photocatalysis has been highly attracting the world-wide attentions among many approaches to convert CO2 into value-added products such as CO, HCOOH, CH3OH and CH4, because photocatalytic conversion of CO2 can be a solution for global warming in terms of its renewability, harmlessness, relatively low cost, and stability. Large number of photocatalysts reported in the research field of the photocatalytic conversion of CO2 require the photoirradiation with deep UV light < 300 nm. Recently, our research group found that Al-doped SrTiO3 photocatalyst (Al-STO), which has been previously reported as a superior photocatalyst for overall water splitting[1], also showed the photocatalytic activity for the conversion of CO2 into CO[2]. In this study, the effect of metal dopant in SrTiO3 on the photocatalytic conversion of CO2 was investigated, and it was found that Mg-doped SrTiO3 showed excellent photocatalytic activity for the conversion of CO2 into CO in the presence of AgCo dual cocatalyst[3].Mg-doped SrTiO3 (Mg-STO) was synthesized by a flux method; the mixture of SrTiO3, MgO, and SrCl2 flux was calcined at 1418 K for 15 h. Ag and Co dual cocatalyst was loaded by a chemical reduction method. An aqueous solution of NaH2PO2 reductant was added to the suspension containing Mg-STO, AgNO3, and Co(NO3)2, and it was kept at 353 K for 90 min with vigorous stirring. Photocatalytic conversion of CO2 with H2O was carried out using an external-irradiation-type reaction vessel. AgCo/Mg-STO was dispersed in an aqueous solution of 0.1 M NaHCO3, and high purity CO2 gas was bubbled into the suspension at a flow rate of 30 mL min−1. The monochromatic UV LED lamp (365 nm) was used as a light source. The gaseous products were analyzed by TCD-GC (H2, O2) and FID-GC equipped with a methanizer (CO).AgCo/Mg-STO exhibited much higher photocatalytic activity for the conversion of CO2 into CO than AgCo/STO and AgCo/Al-STO, which were previously reported. CO was produced at a formation rate of 20 μmol h−1, which was 2.3 times larger than that for Al-STO, and the selectivity toward CO evolution was almost 100 %. H2 formation was completely suppressed in this case. Moreover, the stoichiometric amount of O2 was evolved, indicating that H2O should contribute to the photocatalytic conversion of CO2 as an electron donor. The isotope-labeling experiments using 13CO2 gas as a substrate revealed that the carbon source of CO evolved in this photocatalytic reaction CO2 gas bubbled into the suspension. Therefore, we concluded that CO2 surely split into CO and O2 by the photocatalysis of AgCo/Mg-STO. According to SEM images of undoped STO and Mg-STO, particle shape was obviously changed by Mg doping from pure cubes to irregular edge-shaved cubes. {110} facets were observed in Mg-STO accompanied with {100} facets. Moreover, Ag and Co species were selectively located on the {100} facets and the {110} edge-shaved facets, respectively, after the photoirradiation. The photogenerated electrons and holes were considered to be transferred to {100} and {110} facets separately, and the anisotropic charge transfer should result in the high photocatalytic activity of Mg-STO for the conversion of CO2 with H2O.[1] T. Takata et al., Nature, 2020, 581, 411-414.[2] S. Wang et al., Chem. Sci., 2021, 12, 4940-4948.[3] T. Nakamoto et al., Catal. Sci. Technol., 2023, 13, 4534-4541.

Construction of Ag3PO4/g-C3N4 Z-Scheme Heterojunction Composites with Visible Light Response for Enhanced Photocatalytic Degradation.

Ag3PO4/g-C3N4 photocatalytic composites were synthesized via calcination and hydrothermal synthesis for the degradation of rhodamine B (RhB) in wastewater, and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). The degradation of RhB by Ag3PO4/g-C3N4 composites was investigated to evaluate their photocatalytic performance and cyclic degradation stability. The experimental results showed that the composites demonstrated notable photocatalytic activity and stability during degradation. Their high degradation efficiency is attributed to the Z-scheme transfer mechanism, in which the electrons in the Ag3PO4 conduction band and the holes in the g-C3N4 valence band are annihilated by heterojunction recombination, which greatly limits the recombination of photogenerated electrons and holes in the catalyst and enhances the activity of the composite photocatalyst. In addition, measurements of photocurrent (PC) and electrochemical impedance spectroscopy (EIS) confirmed that the efficient charge separation of photo-generated charges stemmed from strong interactions at the close contact interface. Finally, the mechanism for catalytic enhancement in the composite photocatalysts was proposed based on hole and radical trapping experiments, electron paramagnetic resonance (EPR) analysis, and work function evaluation.

Maximizing Quantum Hole Collection on Anatase TiO2 Thin Films with (001) Facets for Photoelectrochemical Oxigen Evolution Reaction Efficiency

Hydrogen production from water, a key element in the renewable energy portfolio, offers a solution to reduce reliance on fossil fuels. Photoelectrochemical (PEC) hydrogen production, using light-absorbing semiconductors and catalysts, offers a clean and cost-effective method for harnessing solar energy. To enhance the efficiency of PEC, this study explores the use of anatase TiO2 thin film photoelectrodes as an alternative to expensive and rare catalysts, aiming to generate hydrogen as a clean fuel with oxygen as a byproduct.Anatase titanium dioxide is a well-established functional material widely applied in the fields of environment and energy. Recognized as one of the premier materials for photocatalysis and a promising photoanode material for water splitting, titanium dioxide (TiO2) finds use in diverse applications such as dye-sensitized solar cells, perovskite-based solar cells, and cleaning devices. Its band gap of 3.2 eV, stability, strong absorption in the UV region, and energetics of the valence and conduction band edges make anatase particularly suitable for PEC water splitting, especially for the oxygen evolution reaction (OER).Our research focuses on the development of anatase thin films with strong [001] texture and (001) facets at the surface of the film. The (001) facets are known to accumulate photogenerated hole states while the [001] orientation imparts a negative flat band potential. We hypothesize that these two properties, (001) facets and [001] texture, are ideal for OER. This study combines these two structural characteristics within the semiconductor TiO2 layer to enhance PEC performance and maximize the efficiency of hole collection during water oxidation.Anatase TiO2 thin films with (001) facets and [001] orientation were hydrothermally synthesized on a fluorine-doped tin oxide (FTO) substrate and annealed at 500°C. The films exhibited [001] orientation and (001) faceting as shown by grazing incidence X-ray diffraction (GI-XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Photoelectrochemical measurements via cyclic voltammetry in a 0.1 M KOH and Na2SO3 solution demonstrated the films' hole collection efficiency under a 365 nm UV light source. The photoelectrochemical (PEC) and oxygen evolution reaction (OER) characteristics of anatase thin films were observed both under dark and light conditions. Prior to illumination, only the Ti3+/Ti4+ redox couple was observed with an onset potential of 0.01 V (RHE) and negligible OER at anodic potentials. When UV irradiated, the TiO2 thin films exhibited a photocurrent that increased through the anodic scan. The onset potential of photocurrent, measured in the presence of the hole scavenger, exhibited a negative shift ranging from -100 to -200 mV compared to the KOH onset potential. This shift is attributed to the film surface's limited efficiency in collecting holes for water oxidation at low potentials, as rapid recombination kinetics compete with water oxidation. Interestingly, the photocurrent observed with Na2SO3 electrolyte was 0.15 to 0.3 times more than what we saw with KOH electrolyte. Our preliminary results indicate a current density of ~2.0-2.5 mA cm-2 at 1.8 V and a hole collection efficiency of ~84 % at 1.23 V vs RHE, the thermodynamic water oxidation potential. In summary, we have made significant progress toward enhancing the PEC activity of anatase TiO2 thin films by optimizing the film structure for both reactivity and charge transport.

An Enhanced Extend Interface via the π–π Interaction to Achieve the Soluble Light‐Assisted Lithium–Oxygen Batteries

AbstractThe light‐assisted strategy is considered as an effective way to reduce the overpotential of lithium‐oxygen (Li─O2) batteries, however, the generated solid discharge products are prone to cover active sites of the solid‐state photocatalyst, causing the premature death of the cell. Herein, for the first time, the feasibility of soluble photocatalysts in Li─O2 battery system using Iron (II) Phthalocyanine (FePc) is verified. A micro reaction channel is constructed between the sp2‐carbon cathode and the soluble photocatalyst‐phthalein iron through π–π interaction, which can effectively increase the three‐phase reaction interface, facilitating the rapid separation and the transportation of photogenerated electrons and holes, thus improving the photocatalytic efficiency and the reaction kinetics of Li─O2 battery. Moreover, the FePc soluble photocatalysts induced the dual growth modes of surface growth and solution‐mediated growth pathways for the discharge products lead to an additional discharge capacity in the Li─O2 battery. Accordingly, the battery exhibits a lower overpotential of 0.33 V between discharge and charge plateaus at a current density of 0.01 mA cm−2, displaying the excellent cyclic stability (remaining a round‐trip efficiency of 81.1% after 130 cycles). The novel strategy provides new approaches for the construction of the light‐assisted Li─O2 batteries with reduced overpotential and boosted energy efficiency.

Solvent management and Li+/Mg2+ co-doping enable efficient n-i-p NiOx-based perovskite solar cells

Spin-coating pre-fabricated NiOx nanocrystals using an annealing-free process is a compatible technique for fabricating the hole transport layer in n-i-p structured perovskite solar cells. The solvothermal method, assisted by long-chain fatty acids or amines such as oleic acid and oleylamine, has demonstrated the applicability of fabricating NiOx nanoparticles with uniform morphology and size. However, the long-chain fatty acids or amines covering the NiOx nanoparticles cannot be removed at low temperature, obstructing the transport of photo-generated holes due to their insulating characteristics. Herein, triphenylphosphine is employed to replace a portion of oleylamine in the solvothermal reaction solution. Experimental results demonstrate that the introduction of triphenylphosphine does not affect the dispersion of the synthesized NiOx nanoparticles in toluene. The as-fabricated n-i-p structured device receives an efficiency of 12.63 %. Thereafter, Li+ doping and Li+-Mg2+ co-doping strategies are used to further enhance the devices' performance. The best-behaved device with Li+-Mg2+ co-doping NiOx hole transport layer acquires an efficiency of 16.20 %. This research provides a practical approach for fabricating efficient NiOx hole transport materials for n-i-p structured perovskite solar cells.

Highly visible active 2D/2D BiOBr/CO32--Bi2O2CO3 Z-scheme heterojunction for photocatalytic removal of 2-hydroxy-1, 4-naphthoquinone

Photocatalysis technology is utilized for the elimination of water pollutants due to its gentle reaction conditions, affordability, cleanliness, and high efficiency. In this study, BiOBr/CO32--Bi2O2CO3 heterojunctions consisting of BiOBr and CO32- self-doped Bi2O2CO3 components were successfully synthesized by a one-pot hydrothermal method. The photocatalysts were subjected to various testing methods for characterization of their morphology, structure, and photoelectrochemical properties. The photocatalytic efficiency of 2-hydroxy-1,4- naphthoquinone (HNQ) was assessed based on its degradation under visible light irradiation. The findings demonstrated a significant enhancement in the photocatalytic activity of the 50 % BiOBr/CO32--Bi2O2CO3 system, resulting in an impressive degradation rate of 83 % for in 90 min. In addition, the material also has good recoverability and cycle stability, after four cycles, the degradation efficiency remains at 78 %. The free radical capture experiment indicated that•O2- is the active species in the photocatalytic degradation of HNQ. A potential reaction mechanism for the photocatalytic process of the BiOBr/CO32--Bi2O2CO3 Z-scheme heterojunction has been proposed based on experiments trapping free radicals and considering the energy band structure of the catalyst. The successful construction of a heterojunction utilizes photogenerated electrons (e-) and holes (h+) in a more rational manner, which accelerates carrier transfer at the interface and improves the photocatalytic performance of the material. This study can offer a novel idea and approach for the synthesis of Bi-based Z-scheme composite photocatalysts.

In-situ deposition of Ag and AgFeO2 on Bi2WO6 nanosheet for enhancing visible-light-driven photocatalysis toward degradation of tetracycline

A series of novel ternary Bi2WO6/Ag/AgFeO2 composites were successfully prepared by in-situ deposition AgFeO2 onto Bi2WO6 nanosheets, followed by reduction of Ag+ to Ag0 on the surface of Bi2WO6/AgFeO2 via ultrasound-assisted reduction process. The structural characterizations revealed that Ag0 and AgFeO2 was loaded on the smooth surface of Bi2WO6 nanosheets, forming a tightly contact interface. Meanwhile, Bi2WO6 nanosheets as substrates suppressed the aggregation of AgFeO2 nanoparticles. Bi2WO6/Ag/AgFeO2 composites achieved full-spectrum absorption of visible light due to the formation of p-n heterojunction between the Bi2WO6 and AgFeO2 interface and the local surface plasmon resonance (LSPR) of Ag0, as confirmed by UV–vis DRS. Photoelectrochemical results indicated that the formation of both p-n heterojunction and the noble Ag0 improved the separation efficiency of photogenerated electrons and holes. Photocatalysis performance of Bi2WO6/Ag/AgFeO2-80 composite showed that a removal rate of 92.4 % for tetracycline hydrochloride (TC-HCl) under visible light irradiation within 120 minutes, with a kinetic constant 0.01743 min-1, which was 20 times, 15 times, and 3 times higher than that of AgFeO2, Ag/AgFeO2 and Bi2WO6, respectively, and the composite exhibited excellent stability in the fourth cycle experiment. The radical capture experiments proved that superoxide radicals (⸱O2-) play a major role in the degradation process, and the holes (h+) as the second active species. Based on the above results and in situ XPS, a possible electron transfer pathway was proposed.

Constructing cascade electric fields and sulfur vacancies in Ni3S4/NiS2/v-Zn3In2S6 photocatalyst for efficient degradation of contaminants and H2 production

The increasing environmental pollution and looming energy crisis necessitate the development of advanced photocatalysts that demonstrate efficient separation and transfer of the photo-generated holes and electrons, as well as multiple functions to address the above issues. Herein, a bifunctional Ni3S4/NiS2/v-Zn3In2S6 photocatalyst has been constructed to degrade environmental hormones and antibiotics with simultaneous H2 production. Sulfur vacancies have been engineered in the Zn3In2S6 from a kinetic point of view to accelerate the separation of photogenerated charge carriers and act as active sites. Ni3S4 and NiS2 are introduced to construct cascade electric fields with Zn3In2S6 via ohmic junctions for spatially separated charge carriers and reduced hydrogen evolution potential. As a result, the composite exhibits enhanced photocatalytic H2 production and efficient degradation of bisphenol A, norfloxacin, and tetracycline, respectively. Specifically, the degradation pathways of BPA have been investigated based on Fukui calculations and liquid chromatography-mass spectrometry techniques. This work may shed new light on the design and construction of dual-function photocatalysts for wastewater treatment and H2 production.

Constructing ZnIn2S4@WO3·H2O Z-type heterojunction to boost photocatalytic efficiency under visible-light irradiation

In this paper, hexagonal ZnIn2S4 nanoflowers were grown in situ on tetragonal WO3·H2O nanosheets, yielding a compact ZnIn2S4@WO3·H2O (ZIS@WO) core-shell heterojunction. The formation of the ZIS@WO heterojunction was optimized by meticulously adjusting the quantity of WO3·H2O nanosheets incorporated. The crystal structure and microstructure of ZIS@WO were comprehensively examined using XRD, TEM and EDS analyses. The photocatalytic properties of ZIS@WO heterojunctions were evaluated through the degradation of organic pollutants under visible light irradiation. The results demonstrated a marked enhancement in photocatalytic efficiency for the ZIS@WO heterojunction. Further investigation into the separation and transport of photogenerated carriers were performed using PL spectroscopy and photoelectrochemical measurement. Compared to the individual components of ZnIn2S4 nanoflowers and WO3·H2O nanosheets, the ZIS@WO heterojunction creates an internal electric field at the interface, along with a compact core-shell configuration. This internal electric field, in conjunction with the band structure of the heterojunction, effectively accelerates the separation of photogenerated electrons and holes. Additionally, a comprehensive analysis of the photocatalytic degradation mechanisms were presented, elucidating the intricate processes.

Hydrothermal synthesis of CeVO4/g-C3N4 Z-scheme photocatalyst for removal of dyes under photocatalysis

Wastewater treatment emerged as the major concern as the water scarcity increases. Photocatalysis is the efficient way to reduce the pollutants from wastewater without causing destruction to environment. Herein, simplistic preparation of pristine and g-C3N4-CeVO4 nanocomposites for photocatalysis was explored. The structural, optical and vibrational study was confirmed by standard analysis. The samples possess good crystalline nature and g-C3N4 was corroborateed by XRD. The Raman modes were confirmed Ce-O and V-O bending and stretching bonds. The photocatalysts bandgap were narrow down on assisting g-C3N4 and the bandgap engineering was altered by g-C3N4 heterojunction. The morphology of CeVO4 and its composites showed the formation of ball-like structure and the sheets of g-C3N4 was also confirmed. Janus Green B (JG) dye was model pollutant and metal halide lamp was employed as light source. The prepared pure CeVO4 photocatalysts showed better efficiency. Nevertheless, g-C3N4 assisted sample shows good efficiency and greater rate constant. This was characteristic feature of proper heterojunction development amid g-C3N4 and CeVO4. CeVO4, 0.1 g g-C3N4-CeVO4 and 0.2 g g-C3N4- CeVO4 rate constant were 9.2 × 10-4, 1.1 × 10-2, 1.54 × 10-2 and 2 × 10-2 min−1. The photogenerated electrons and holes were enthusiastically break up and reactive species were generated which paved the path for enhanced photocatalytic removal of pollutants. Among various photocatalysts, 0.2 g g-C3N4-CeVO4 is prospective material for wastewater remediation process.

The electronic stopping power of self-irradiated molybdenum in different charge states

Molybdenum is not only an excellent photovoltaic material but also a crucial component in semiconductors. However, its high bandgap restricts its application in optoelectronic devices. This limitation arises primarily because the energy barrier between photogenerated electron-hole pairs cannot be directly overcome by sunlight. Self-irradiation can overcome these barriers, allowing efficient separation of photogenerated electrons and holes, making molybdenum an excellent light-absorbing material. By altering the charge state of molybdenum-based materials, their light absorption can be adjusted. This project aims to systematically study the optical properties and electronic stopping power of molybdenum-based materials in different charge states through theoretical calculations and experiments.

The Influence of Electrolytes on the Performance of Self-Powered Photoelectrochemical Photodetector Based on α-Ga2O3 Nanorods.

Photodetectors have a wide range of applications across various fields. Self-powered photodetectors that do not require external energy have garnered significant attention. The photoelectrochemical type of photodetector is a self-powered device that is both simple to fabricate and offers high performance. However, developing photoelectrochemical photodetectors with superior quality and performance remains a significant challenge. The electrolyte, which is a key component in these detectors, must maintain extensive contact with the semiconductor without degrading its material quality and efficiently catalyze the redox reactions of photogenerated electrons and holes, while also facilitating rapid charge carrier transport. In this study, α-Ga2O3 nanorod arrays were synthesized via a cost-effective hydrothermal method to achieve a self-powered solar-blind photodetector. The impacts of different electrolytes-Na2SO4, NaOH, and Na2CO3-on the photodetector was investigated. Ultimately, a self-powered photodetector with Na2SO4 as the electrolyte demonstrated a stable photoresponse, with the maximum responsivity of 0.2 mA/W at 262 nm with the light intensity of 3.0 mW/cm2, and it exhibited rise and decay times of 0.16 s and 0.10 s, respectively. The α-Ga2O3 nanorod arrays and Na2SO4 electrolyte provided a rapid pathway for the transport of photogenerated carriers and the built-in electric field at the semiconductor-liquid heterojunction interface, which was largely responsible for the effective separation of photogenerated electron-hole pairs that provided the outstanding performance of our photodetector.

Electron Tandem Transport Channel in a Cu3P/Sv-ZnIn2S4 p-n Heterojunction for Photothermal-Photocatalytic Benzyl Alcohol Oxidation and H2 Production.

The development of photocatalytic systems with an electron tandem transport channel represents a promising avenue for improving the utilization of photogenerated electrons and holes despite encountering significant challenges. In this study, ZnIn2S4 (Sv-ZIS) with sulfur vacancies was fabricated using a solvothermal technique to create defect energy levels. Subsequently, Cu3P nanoparticles were coupled onto the surface of Sv-ZIS, forming a Cu3P/Sv-ZIS p-n heterojunction with an electron tandem transport channel. Experimental findings demonstrated that this tandem transport channel enhanced the carrier lifetime and separation efficiency. In addition, mechanistic investigations unveiled the formation of a robust built-in electric field (BEF) at the interface between Cu3P and Sv-ZIS, providing a driving force for electron migration. The combined consequences of the transport channel, the strong BEF, and photothermal effect led to a surface carrier separation efficiency of 65.85%. Consequently, Cu3P/Sv-ZIS achieved simultaneous H2 yield and benzaldehyde production rates of 18,101.4 and 15,012.6 μmol·g-1·h-1, which were 2.31 and 2.62 times higher than those of ZnIn2S4, respectively. This work exemplifies the design of the p-n heterojunction for the efficient utilization of photogenerated electrons and holes.

Integrating Polyoxometalates and Silver Clusters into Atomically Precise Molecular Heterojunction.

The Ag cluster-POM assemblies have been shown to possess interesting and potentially useful properties. However, there is no precedent example of atomically precise Ag cluster-POM assemblies showing heterojunction effects in photocatalysis. Herein, the synthesis and total structure determination of the periodically distributed molecular heterojunction [Ag12(SCy)6(CH3CN)12(PW12O40)]n (Ag12-PW12) are reported. The assembly of Ag/W clusters into 3D network can endow the resulting binary structure with an aesthetic topology and unique physicochemical properties. More remarkably, the incorporation of Ag12 cluster with PW12 can efficiently facilitate the separation of photogenerated electrons and holes, thus significantly promoting the catalytic efficiency in selective oxidation of sulfides. The Ag12-PW12 heterojunction can be recovered and reused five times with no drastic change in the catalytic performance. This research is expected to assist in the rational design of cluster-based heterojunction catalysts. The increase of catalytic activity of the Ag12-PW12 assembly in comparison with the unassembled Ag12 and PW12 clusters is attributed to the synergistic effect of Ag12 and PW12 clusters, offering the splendid opportunity for deciphering structure-reactivity relationship of heterostructure-coupled photosystem.

UVA light assisted activation of sulfite by metal–organic framework-derived FeOx@C catalyst for organic degradation: Formation and role of non-radical species

Advanced oxidation processes (AOPs) based on sulfite (S(IV)) activation are gaining recognition as a promising Fenton-like strategy, primarily due to their ability to generate potent radicals (e.g., SO4− and HO). However, the existence and role of a non-radical-driven oxidation pathway in the S(IV)-mediated degradation of contaminants remain under debate. Herein, a magnetic iron-carbon composite (FeOx@C) was fabricated using the MOF-templated method and utilized as a stable photocatalyst to activate S(IV) under UVA light, achieving >93.6 % degradation of 20 μM ofloxacin (OFL) with a high degradation rate constant of 0.073 min−1 within 45 min. The catalyst’s porous carbon structure facilitated the transport of substrates to active sites and shortened the diffusion distance between reactive species and contaminants. Adsorbed S(IV) donated one electron to photo-generated holes and exposed Fe(III) sites with the formation of SO5−, which then followed two distinct pathways to produce radicals (SO4−) and non-radicals (Fe(IV) and 1O2) responsible for OFL degradation. By leveraging the synergy of both radicals and non-radicals, this innovative oxidative system showcased robust anti-interference capacities and exceptional performance in degrading contaminants from complex water matrices. This study provides new insights into the significant role of non-radical species in S(IV)-mediated decontamination processes.

Facile synthesis of Pt clusters decorated TiO2 nanoparticles for efficient photocatalytic degradation of antibiotics

AbstractTiO2 has attracted much attention in the field of photocatalytic degradation of antibiotics due to its good photostability, nontoxicity, and low cost. However, the rapid recombination of photogenerated carriers limits the further improvement of its photocatalytic activity. Here, a facile microwave‐assisted hydrothermal method has been developed to prepare Pt clusters decorated TiO2 nanoparticles. Pt clusters ranging in size from 1 to 2 nm are uniformly distributed across the surface of the TiO2 matrix. A pronounced charge transfer phenomenon is discernible between the Pt and TiO2 components. It is revealed that the charge transfer enables faster transfer and separation of photogenerated electrons and holes, which are beneficial for the improvement of photocatalytic degradation of both ofloxacin and levofloxacin. The degradation capability can be attributed to the efficient generation of •OH or •O2− species within the solution. The parallel adsorption model of TiO2 on antibiotic molecules is verified, and the degradation reaction pathway has been elucidated. This work provides a facile method for optimizing the performance of TiO2 photocatalysts, which can be extended to other oxide photocatalysts.

Synergy of Photogenerated Electrons and Holes toward Efficient Photocatalytic Urea Synthesis from CO2 and N2

AbstractDirectly coupling N2 and CO2 to synthesize urea by photocatalysis paves a sustainable route for urea synthesis, but its performance is limited by the competition of photogenerated electrons between N2 and CO2, as well as the underutilized photogenerated holes. Herein, we report an efficient urea synthesis process involving photogenerated electrons and holes in respectively converting CO2 and N2 over a redox heterojunction consisting of WO3 and Ni single‐atom‐decorated CdS (Ni1‐CdS/WO3). For the photocatalytic urea synthesis from N2 and CO2 in pure water, Ni1‐CdS/WO3 attained a urea yield rate of 78 μM h−1 and an apparent quantum yield of 0.15 % at 385 nm, which ranked among the best photocatalytic urea synthesis performance reported. Mechanistic studies reveal that the N2 was converted into NO species by ⋅OH radicals generated from photogenerated holes over the WO3 component, meanwhile, the CO2 was transformed into *CO species over the Ni site by photogenerated electrons. The generated NO and *CO species were further coupled to form *OCNO intermediate, then gradually transformed into urea. This work emphasizes the importance of reasonably utilizing photogenerated holes in photocatalytic reduction reactions.

Synergy of Photogenerated Electrons and Holes toward Efficient Photocatalytic Urea Synthesis from CO2 and N2.

Directly coupling N2 and CO2 to synthesize urea by photocatalysis paves a sustainable route for urea synthesis, but its performance is limited by the competition of photogenerated electrons between N2 and CO2, as well as the underutilized photogenerated holes. Herein, we report an efficient urea synthesis process involving photogenerated electrons and holes in respectively converting CO2 and N2 over a redox heterojunction consisting of WO3 and Ni single-atom-decorated CdS (Ni1-CdS/WO3). For the photocatalytic urea synthesis from N2 and CO2 in pure water, Ni1-CdS/WO3 attained a urea yield rate of 78 μM h-1 and an apparent quantum yield of 0.15 % at 385 nm, which ranked among the best photocatalytic urea synthesis performance reported. Mechanistic studies reveal that the N2 was converted into NO species by ⋅OH radicals generated from photogenerated holes over the WO3 component, meanwhile, the CO2 was transformed into *CO species over the Ni site by photogenerated electrons. The generated NO and *CO species were further coupled to form *OCNO intermediate, then gradually transformed into urea. This work emphasizes the importance of reasonably utilizing photogenerated holes in photocatalytic reduction reactions.

Light-induced, room-temperature hydrogen gas detection based on SnO2 quantum Dots/p-Si

The continuous monitoring of the hydrogen gas level under low-temperature conditions is vital to prevent explosive accidents. Metal oxide-based chemoresistors have attracted significant attention owing to their excellent gas sensitivity. However, high operating temperature required to remove adsorbed oxygen species is still considered as an obstacle, limiting the application of the system. In addressing the temperature issue, this study introduced an approach in which a gas interaction layer was separated from the signal-sensing region. The proposed two-terminal device comprises a gas interaction layer of SnO2 quantum dots (QDs) and a p-doped silicon (p-Si) region characterized by high electronic conductivity and light sensitivity. Through visible light illumination, the recombination between gas interaction-induced electrons and photo-generated holes induces a change in output photocurrent, enabling room-temperature gas sensing without additional temperature control. Using this gas sensing scheme, the proposed sensor showed impressive gas detection performance in the low-temperature range, achieving a detection range of a few parts per million (ppm) in concentration (limit of detection range: 9.46–50 ppm).