Photo-excited Charge Research Articles

Spectroscopic Kinetic Insights into the Critical Role of Metal-Oxide Interfaces in Enhancing the Concentration of Surface-Reaching Photoexcited Charges.

Surface modification of semiconductors with noble metals has been shown to effectively tune their photocatalytic activity. However, the photoinduced charge transfer processes at the metal/semiconductor interface and their impact on the concentration of surface-reaching photoexcited charges remain subjects of ongoing debate. In this study, we used time-resolved spectroscopy and kinetic analysis to investigate the behavior of surface-reaching photoholes in metal-loaded TiO2 nanoparticles. Our results reveal that the concentration of surface-reaching photoholes (Ch+(surf)) is highly dependent upon the type of metal and the resulting metal-oxide interface. Among the noble metals studied (Pt, Au, and Ag), Pt loading led to the most significant increase in Ch+(surf), with a nearly 3-fold enhancement compared to pristine TiO2. This enhancement was attributed to the generation of more abundant Ti3+ defects at the metal-oxide interface, which serve as hole trap states, thereby accelerating interfacial charge transfer, improving charge separation, and enriching Ch+(surf). These findings underscore the critical role of the metal-oxide interface in enhancing surface-reaching photoexcited charges, offering valuable insights for the design of advanced materials for solar energy conversion.

Probing interfacial states in β-Ga2O3/SiO2 TFTs for high-response broad-band photodetection

Mechanically exfoliated β-Ga2O3 flakes preserve bulk material's single crystallinity for easy integration but suffer from interfacial defects that greatly influence device performance. In this paper, we report a quantitative characterization of interfacial states in phrase β-Ga2O3/SiO2 thin-film transistors and then propose their beneficial application in achieving high-response broad-band photodetection. Photo-excited charge collection spectroscopy technique was employed to probe the interfacial states, revealing a substantial density (∼4 × 1012 cm−2 eV−1) of deep-level states ranging from 2.5 to 3.7 eV below the conduction band. Intriguingly, a photoresponsivity as high as 2 × 104 A/W was achieved via utilizing these interfacial states, along with the tunable broad-band response ranging from 335 to 496 nm. This research enhances both the well-industrialized silicon devices and the emerging β-Ga2O3 technologies. Furthermore, it introduces a profound concept: defects, once seen as flaws, can be assets when their characteristics are thoroughly understood.

Solution Process–Based Facile Flame–Boosted Low‐Valence Transition Metal Doping on Pristine Oxide for Highly Enhanced Photoelectrochemical Solar Water Oxidation Reaction

ABSTRACTAs for the high sustainable solar hydrogen production via water splitting, transition metal doping on an oxide photoanode in photoelectrochemical (PEC) cells has been recognized as an effective approach. However, conventional thermal‐diffusion‐mediated doping strategies face the challenge of resolving sluggish catalytic kinetics for oxygen evolution reaction (OER) and its practical utilization for the synthesis of photoanode films. Herein, we introduce facile ultrafast flame‐boosted doping of Mo into a BiVO4 (FL MoBVO) film for 20 s to achieve an efficient PEC OER. Mo elements in a low‐valence state (i.e., Mo6−δ) and Mo6+ are successfully doped into the photoanode, which manipulate the energy band structure, facilitating the downward shift of band edges and promoting the surface catalytic kinetics. Consequently, the flame‐boosted Mo‐doping results in superior PEC performance in a mild environment with neutral electrolyte without introducing any other additives or co‐catalysts, where the photocurrent density at 1.23 VRHE under 1 sun illumination in pH 7 is outstandingly enhanced, over 9‐fold higher than that of a pristine BiVO4. The flame‐boosted doping induces significantly enhanced photoexcited charge transport and catalytic reaction kinetics performances simultaneously. Our report provides the effective strategy boosting both the thermodynamic and kinetic charge migration properties for sustainable materials.

Low-temperature transport and relaxation of photo-carriers in TiS2

The investigation of non-equilibrium carrier dynamics in two-dimensional semi-metallic materials, particularly at low temperatures, is crucial for elucidating their fundamental properties, including carrier–carrier interactions and electron–phonon scattering mechanisms. In this study, we examine the behavior of 1T-TiS2, utilizing scanning photocurrent microscopy, bias voltage-adjustable photoresponse measurements, and pump-probe techniques to explore the temperature-dependent transport and relaxation of photo-excited charge carriers. We observe a non-monotonic intrinsic photocurrent in the biased device, with a pronounced peak feature occurring at approximately 25 K, which is corroborated by pump-probe measurements that reveal a similar peak in the magnitude and relaxation time of the differential reflectance as a function of the temperature. Our results highlight the unique carrier dynamics in TiS2, offering valuable insights for the design of TiS2-based optoelectronic devices that can operate effectively across a wide temperature range.

Unusually high selectivity (100 %) of photocatalytic C[sbnd]C coupling achieved by instant reverse reduction of byproducts

The photocatalytic CC coupling of benzyl alcohol (BA) into hydrobenzoin (HB), is appealing to obtain high-value chemicals. However, the selectivity of HB is still low due to the inevitable formation of benzaldehyde. Herein, we report In(OH)3-ZnS photocatalyst for CC coupling of BA into HB with very high selectivity (∼100 %). The introduction of In(OH)3 onto ZnS with stable interaction facilitates light harvesting and separation of photo-excited charges. As a result, BA conversion on optimized In(0.1)-ZnS catalyst (73 %) is much higher than ZnS (29 %). Besides, the surface hydroxyl groups derived from In(OH)3 enables the facile desorption of CH(OH)Ph radical. Therefore, the over oxidation of CH(OH)Ph radical into by-product of benzaldehyde can be effectively inhibited. More significantly, in-situ FTIR spectra and reduction of by-product manifest the instant reverse reduction process of benzaldehyde into CH(OH)Ph radical during CC coupling of BA, which is the key to realizing satisfied HB selectivity (100 %). Theoretical simulations reveal that the weak adsorption of CH(OH)Ph radical over catalyst and the high energy barrier of over-oxidation of CH(OH)Ph into benzaldehyde contributes to the formation of highly selective coupling products. This work will inspire new insights to design rational photoredox systems for organic transformations with high selectivity.

Vertical Electric-Field-Induced Switching from Strong to Asymmetric Strong-Weak Confinement in GaAs Cone-Shell Quantum Dots Using Transparent Al-Doped ZnO Gates.

The first part of this work evaluates Al-doped ZnO (AZO) as an optically transparent top-gate material for studies on semiconductor quantum dots. In comparison with conventional Ti gates, samples with AZO gates demonstrate a more than three times higher intensity in the quantum dot emission under comparable excitation conditions. On the other hand, charges inside a process-induced oxide layer at the interface to the semiconductor cause artifacts at gate voltages above U≈ 1 V. The second part describes an optical and simulation study of a vertical electric-field (F)-induced switching from a strong to an asymmetric strong-weak confinement in GaAs cone-shell quantum dots (CSQDs), where the charge carrier probability densities are localized on the surface of a cone. These experiments are performed at low U and show no indications of an influence of interface charges. For a large F, the measured radiative lifetimes are substantially shorter compared with simulation results. We attribute this discrepancy to an F-induced transformation of the shape of the hole probability density. In detail, an increasing F pushes the hole into the wing part of a CSQD, where it forms a quantum ring. Accordingly, the confinement of the hole is changed from strong, which is assumed in the simulations, to weak, where the local radius is larger than the bulk exciton Bohr radius. In contrast to the hole, an increasing F pushes the electron into the CSQD tip, where it remains in a strong confinement. This means the radiative lifetime for large F is given by an asymmetric confinement with a strongly confined electron and a hole in a weak confinement. To our knowledge, this asymmetric strong-weak confinement represents a novel kind of quantum mechanical confinement and has not been observed so far. Furthermore, the observed weak confinement for the hole represents a confirmation of the theoretically predicted transformation of the hole probability density from a quantum dot into a quantum ring. For such quantum rings, application as storage for photo-excited charge carriers is predicted, which can be interesting for future quantum photonic integrated circuits.

Quantitative Spectroscopic Analysis of Surface-Reaching Photoexcited Holes in g-C3N4/TiO2 Z-Scheme Heterojunctions.

The Z-scheme heterojunction has been demonstrated to be effective in tuning the photocatalytic performance of photocatalysts. However, there is still a lack of quantitative and in-depth research on how the Z-scheme heterojunction affects the concentration of surface-reaching photoexcited charges. Here, by combining time-resolved spectroscopies and kinetic analysis, the concentration of surface-reaching photoholes (Ch+(surf)) within g-C3N4/TiO2 Z-scheme heterojunctions was quantitatively analyzed for the first time. Quantitative measurements reveal that Ch+(surf) of the prepared Z-scheme photocatalysts is highly dependent on the g-C3N4 content and the induced Z-scheme heterojunctions at the g-C3N4/TiO2 interface. Encouragingly, we found that a properly engineered Z-scheme heterojunction with close coupling of g-C3N4 and TiO2 can significantly increase the Ch+(surf), leading to nearly a 1.7-fold increase compared with pristine TiO2 samples. Furthermore, a distinct hole trap state-mediated Z-scheme charge transfer mechanism was uncovered in which the intrinsic interface defects at the g-C3N4/TiO2 junction act as hole traps, accelerating interface electron-hole recombination, thereby boosting spatial charge separation and ultimately enriching the Ch+(surf). This work provides insights into understanding and controlling electron pathways and Ch+(surf) in Z-scheme photocatalysis, with implications for the screening of different types of direct Z-scheme photocatalysts.

Atomic Dispersed Co on NC@Cu Core-Shells for Solar Seawater Splitting.

With freshwater resources becoming increasingly scarce, the photocatalytic seawater splitting for hydrogen production has garnered widespread attention. In this study, a novel photocatalyst consisting of a Cu core coated is introduced with N-doped C and decorated with single Co atoms (Co-NC@Cu) for solar to hydrogen production from seawater. This catalyst, without using noble metals or sacrificial agents, demonstrates superior hydrogen production effficiency of 9080 µmolg-1h-1, i.e., 4.78% solar-to-hydrogen conversion efficiency, and exceptional long-term stability, operating over 340h continuously. The superior performance is attributed to several key factors. First, the focus-light induced photothermal effect enhances redox reaction capabilities, while the salt-ions enabled charge polarization around catalyst surfaces extends charge carrier lifetime. Furthermore, the Co─NC@Cu exhibits excellent broad light absorption, promoting photoexcited charge production. Theoretical calculations reveal that Co─NC acts as the active site, showing low energy barriers for reduction reactions. Additionally, the formation of a strong surface electric field from the localized surface plasmon resonance (LSPR) of Cu nanoparticles further reduces energy barriers for redox reactions, improving seawater splitting activity. This work provides valuable insights into intergrating the reaction environment, broad solar absorption, LSPR, and active single atoms into a core-shell photocatalyst design for efficient and robust solar-driven seawater splitting.

Chemically bonded nonmetallic LSPR S-scheme hollow heterostructure for boosting photocatalytic performance

The light absorption, mass transfer, and charges separation are essential to the efficiency of photocatalytic reaction, but constructing photocatalyst with the three excellent properties is still challenging. Herein, the interfacial Mo-S bonds and oxygen vacancy synchronously decorated MoO3-x/Zn3In2S6 (MoO3-x/ZIS) heterostructure was rationally designed and synthesized. The oxygen-defective MoO3-x nanotubes showed hollow structure and local surface plasmonic resonance (LSPR) effect, which improved mass transfer and solar light absorption. Besides, the built-in electric field and interfacial Mo-S bond provided endogenetic impetus and channels for rapid photoexcited charge carriers transfer and separation. The photocatalytic hydrogen (H2) evolution and hydrogen peroxide (H2O2) production on optimal MoO3-x/ZIS composite were 17.34 and 4.47 mmol g−1 h−1, respectively. The apparent quantum efficiency of MoO3-x/ZIS for H2 evolution at 400 nm was about 13.92 %, which was 8.09 times higher than that of ZIS. Moreover, the MoO3-x/ZIS also displayed excellent activities on the selective 5-hydroxymethylfurfural dehydrogenation. The in-situ X-ray photoelectron spectroscopy, electron paramagnetic resonance, in-situ selective photodeposition, and density functional theory calculation confirmed the S-scheme charge transfer pathway between MoO3-x and ZIS. This study provides an effective avenue for designing multifunctional photocatalysts based on the synergistic effects of chemically bonded S-scheme heterostructure and nonmetallic LSPR effect.

Quantitative photocurrent scanning probe microscopy on PbS quantum dot monolayers.

Photoconductive atomic force microscopy can probe monolayers of PbS/perovskite quantum dots (QDs) with a contact area of 1-3 QDs in stable and reproducible acquisition conditions for I/V curves and photocurrent maps. From the measurements, quantitative values for the barrier height, built-in voltage, diffusion constant and ideality factor are deduced with high precision. The data analysis is based on modelling a superposition of the drift current of the photo-excited charges and a diffusion current across the interface barriers, providing physical insight into the underlying processes. Besides looking into PbS/perovskite on an indium tin oxide substrate, it is shown how the photocurrent is modified by changing either the QD ligand (to thiocyanate) or the substrate (to micro- and nanostructured gold). The dependence of the photocurrent on the light irradiance is found to follow a power law with an exponent of 0.64. Generally, quantitative measurements with high spatial resolution (on the single QD level) can provide significant insight into the processes in nanostructured hybrid optoelectronic components.

Metal oxide-combined sol-gel synthesized ceria nanoparticles: An operative photocatalyst for visible-light-driven mineralization of ciprofloxacin antibiotic in water

The superb spreading of antibiotic waste represents a vital issue related to water and soil contamination that distress the environment and humankind. Accordingly, various research projects for the eco-friendly degradation of such contaminants. Here, we envisioned the coupling of narrow bandgap (Eg) metal oxide with copolymeric-assisted sol-gel-prepared ceria nanoparticles (CeO2) for photoelimination of ciprofloxacin (CiP) as a model for antibiotic waste in water. The few tens nanometer-sized cubic CeO2 was receptive to the irradiated visible light by a combination of a few nanometer-sized AgVO3, Bi2O3, and CoTiO3 at 10.0 wt% by simple precipitation of their salt precursors. The designed nanostructures exposed mesoporous surfaces similar to the pristine CeO2 with a specific surface area range of 165–169 m2 g−1. The 1.25 mg mL−1 dose CoTiO3-composited CeO2 displayed the best-performed photomineralization of CiP (98 ± 1.2 %) within only 2 h of light illumination compared to added oxides with an outstanding reaction rate of 0.0297 min−1. In addition, the CoTiO3/CeO2 displayed a bearable recyclability of five times with 93 % of its mineralization efficiency. The boosted photoactivity of CoTiO3/CeO2 is referred to the momentous light captivation and a band alignment with Eg minimization to 2.48 eV. Also, the constructed heterojunction among n-type CoTiO3 and n-type CeO2 has improved the photoexcited charge separation and migration as resolved by high photocurrent and photoluminescence suppression. Such a comparative study proposes an efficient photocatalyst design for clean and sustainable antibiotic waste remediation.

GPU-accelerated on-the-fly nonadiabatic semiclassical dynamics.

GPU-accelerated on-the-fly nonadiabatic dynamics is enabled by interfacing the linearized semiclassical dynamics approach with the TeraChem electronic structure program. We describe the computational workflow of the "PySCES" code interface, a Python code for semiclassical dynamics with on-the-fly electronic structure, including parallelization over multiple GPU nodes. We showcase the abilities of this code and present timings for two benchmark systems: fulvene solvated in acetonitrile and a charge transfer system in which a photoexcited zinc-phthalocyanine donor transfers charge to a fullerene acceptor through multiple electronic states on an ultrafast timescale. Our implementation paves the way for an efficient semiclassical approach to model the nonadiabatic excited state dynamics of complex molecules, materials, and condensed phase systems.

Sustainable carbonaceous material from durian peel to modify the photocatalytic activity of Ag/activated carbon/BiVO4 for RhB degradation under visible light irradiation

High performance and sustainable Ag/activated carbon (AC)/BiVO4 photocatalyst was synthesized via hydrothermal method, followed by photodeposition of Ag. The AC was derived from organic waste of Monthong durian peels which was recycled to achieve carbon neutrality and encourage sustainable friendly environment. The AC modified band energy and promoted reducing power of the obtained photocatalyst with increasing of oxygen vacancies for electron trapping on the photocatalyst surface, thus enhancing photoexcited charge separation and producing more active species as evidenced by PL, EIS, and scavenger experiment. With the modification of Ag, the photoexcited electrons are efficiently trapped that the available h+ are mobilized through the oxygen vacancies occurring by modified high electron density of AC and Ag thus enhanced photocatalytic performance as exhibited by XPS. The band energy alignment of the developed Ag/AC/BiVO4 is proposed with the improved photocatalytic RhB degradation.

Enhanced light harvesting ability in hollow Pt/TiO2 nanoreactor for boosting tetracycline photodegradation

Utilizing solar energy to decompose tetracycline (TC) is a green strategy to treat wastewater. Herein, a heterogeneous hollow structured TiO2 decorated Pt nanoparticles were successfully designed and synthesized via hard-template approach and photo-deposition process toward TC photodegradation. The Pt nanoparticles loaded on the surface of hollow structured TiO2 can increase the visible light absorption due to the local surface plasmon resonance (LSPR) effect. Furthermore, owing to the tough electron oscillation of the LSPR excitation, the plasmonic hot holes on the surface of Pt nanoparticles can capture the electrons of TiO2, effectively facilitating the separation of photo-excited charge carriers because of the formation of Schottky junction constructed between Pt and TiO2. Combined the natural merits of shorten conveying path of charge carriers and physical structural stability for hollow structure, the optimal Pt/TiO2 hetero-junction hybrid showed superior photocatalytic activity and durability for TC photodegradation with the degradation efficiency of 93.8 ​% after 30 ​min and the rate constant of 0.09196 min−1 under 300 ​W Xe lamp irradiation. This work displays a heterogeneous hybrids catalyst based on eco-friendly metal and semiconductor materials which can be used in the fields including without limitation TC photodegradation.

Linking the Doping-Induced Trap States to the Concentration of Surface-Reaching Photoexcited Holes in Transition-Metal-Doped TiO2 Nanoparticles.

Transition-metal doping has been demonstrated to be effective for tuning the photocatalytic activity of semiconductors. Nonetheless, the impact of doping-induced trap states on the concentration of surface-reaching photoexcited charges remains a topic of debate. In this study, through time-resolved spectroscopies and kinetic analysis, we found that the concentration of surface-reaching photoholes (Ch+(surf)) in doped TiO2 nanoparticles sensitively relies on the type of dopants and their associated trap states. Among the studied dopants (Fe, Cu, and Co), Fe doping resulted in the most significant increase in Ch+(surf), nearly double that of Co or Cu doping. Fe-doping induced more effective hole trap states, acting as the mediator for interfacial charge transfer, thus accelerating charge separation and consequently enriching Ch+(surf). This work provides valuable insight into understanding and controlling Ch+(surf) in transition-metal-doped TiO2 materials.

Synthesis, characterization and estimation of performance parameters of binary ZnO–SnO2/p-Si heterojunction solar cells

The present work demonstrates the successful synthesis of binary ZnO–SnO2 nanocomposite employing a simple and efficient sol-gel method. The XRD spectra confirmed the formation of a highly crystalline domain indexed to (100) planes of ZnO and (101) and (310) planes of SnO2. The UV–vis spectroscopy analysis revealed high transmittance over 85 % and good optical absorption, a desirable aspect for efficiency enhancement of the cell by heightened photo-excited charge carrier generation through an increased number of incident photons being striking at the junction. The optical band gap was determined using the Taucs formula and found to be 3.51 eV. To probe the possible application of ZnO–SnO2 in Heterojunction Solar Cells (HJSCs), we carried out a numerical simulation for the estimation of cell parameters using MATLAB. The result revealed that the work function (WF) does not have a significant effect on short circuit current density (Jsc), whereas the open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE) significantly depend on the material work function. Typically VOC increased from 0.155 V to 0.665 V, FF increased from 0.586 to 0.838 and the PCE could be enhanced from 2.55 % to 15.74 %, with an estimated WF range of 4.5 eV–4.0 eV. The effect of substrate thickness was also studied, indicating increment in parameters in the range from 25 μm to 200 μm, however, no significant effect was noticed for thickness >200 μm. The simulation provides optimization of semiconductor properties through the estimation of cell parameters such as PCE, Voc, Jsc and FF for enhanced performance.

Gd and Ni co-doped BiFeO3 ferrite/r-GO nanocomposite for photocatalytic environmental remediation applications

Synergistic effects of the co-doping of rare earth and transition metals on the structural, electrical and optical, in multi-ferroic BiFeO3 nanoferrites (NFs) combined with reduced graphene oxide (r-GO) nanosheets, photocatalytic degradation properties can be boosted. In this current study gadolinium and nickel-co-doped Bi1-xGdxFe1-yNiyO3 were synthesised via the tartaric acid-assisted sol-gel method and their composite Bi1-xGdxFe1-yNiyO3/r-GO with 10 % reduced graphene oxide (r-GO) via the ultra-sonication route. Phase and structural investigation were carried out using x-ray diffraction (P-XRD), Raman scattering, and Fourier transform infrared (FTIR) analysis, which confirms the successful fabrication of co-doping in the rhombohedral geometry of the perovskite-type Bi1-xGdxFe1-yNiyO3. Electrical conductivity of the fabricated composite material was observed to increase because of the co-doping and the addition of r-GO. Photoluminescence (PL) spectra of co-doped and r-GO composite material exhibited a decline in PL intensity because optical bandgap energies exhibited narrowing of 1.99 eV and 1.91 eV respectively, which indicates the excellent separation and stabilization of photo-excited charge pairs. Special conduction properties of r-GO nanosheets improved electrical and optical properties, a well-porous nature, large surface area, lower bandgap, and increased dye degradation in the Bi1-xGdxFe1-yNiyO3/r-GO photocatalyst showing excellent photo-degradation of cationic malachite green (M.G.) dye, achieving a degradation efficiency of 96.4 % under natural solar light. Hence, the photocatalyst shows excellent stability where quenching of radicals using selective scavengers shows that OH* radicals and e−/h+ pairs are primarily involved in the mechanism of photo-degradation in a basic pH medium, making the as-fabricated material a potential material for photo-catalytic environmental remediation.

Interfacial engineering of 0D/2D CoMn2O4 nanoparticles/CdS nanosheets p-n heterostructures for boosted photocatalytic H2 production and U(VI) reduction

Developing effective heterojunction photocatalysts that efficiently separate charge carriers and improve light-harvesting capabilities is crucial in addressing energy and environmental issues. Herein, a unique nanocomposite photocatalyst is constructed by attaching CoMn2O4 nanoparticles onto 2D CdS nanosheets for H2 production and U(VI) reduction. The optimized 2% CoMn2O4/CdS nanocomposite showcases the highest photocatalytic H2 production efficiency, 5.8 times higher than CdS nanosheets. Additionally, the U(VI) reduction rate constant of 2% CoMn2O4/CdS is 0.0192 min−1, approximately 1.9 folds over the pristine CdS (0.0101 min−1). The exceptional photocatalytic performance toward photocatalytic H2 evolution and U(VI) reduction reactions directly result from the electronic integration between CoMn2O4/CdS p-n heterojunction, facilitated by the efficient photoexcited charge separation. Feasible photocatalytic mechanisms are proposed through experimental analyses and theoretical calculations. This study provides a straightforward method for designing effective CdS-based heterostructured photocatalysts, contributing to the advancement of solar-to-H2 conversion and environmental abetment.

Metal single atom-oxygen modification induced transformation of carbon nitride-based heterojunctions from type-II to S-scheme for efficient photocatalytic overall water splitting

Constructing semiconductor S-scheme hetero-(homo-)junctions (SSHs) is one of the most effective ways to enhance the photocatalytic overall water splitting (POWS) performance, but encumbered by deficiency of efficient water-oxidizing semiconductors. Herein, tungsten single atom-oxygen group (W-O) modified polymeric carbon nitride (WPCN, an example of metal single atom-oxygen group modified PCN) was used as a water-oxidizing semiconductor to construct a CdS/WPCN SSH, for which the W-O modification plays a key role that causes transformation from a PCN/CdS type-II heterojunction to the CdS/WPCN SSH which exhibits remarkably enhanced photoexcited charge separation than single CdS and WPCN. Pt-CdS/WPCN exhibits 2.6 and 7.2 times higher POWS activity than Pt-WPCN and Pt-CdS, respectively, further demonstrating the key role of the SSH, and lower activity than Pt@Cr2O3-CdS/WPCN that exhibits 5.4-fold higher activity than Pt@Cr2O3-PCN/CdS, and especially, higher photochemical stability by suppressing rapid photocorrosion of CdS. The solar-to-hydrogen conversion efficiency of Pt@Cr2O3-CdS/ WPCN reaches 0.014 %, with an external quantum yield of 0.093 % at 420 nm. This work reveals the role of metal single atom-oxygen modification of PCN in SSHs and provides a way to suppress rapid photocorrosion of CdS.

“Light battery” role of long afterglow phosphor for round-the-clock environmental photocatalysis

Owing to its convenient, sustainable and green process, photocatalysis has become a feasible technique for solving environmental pollution issues. So far, significant achievements have been realized in photocatalytic pollutant elimination. Nevertheless, photocatalytic processes require a continuous external light illumination to drive photoredox reactions, seriously prohibiting their applications in darkness. In this context, exploring a photocatalyst with reliable photocatalytic activity in dark condition is therefore highly meaningful and an ultimate target of photocatalysis technique. Recently, long afterglow phosphor has aroused great attention due to its “light battery” role for driving catalytic reactions in dark conditions. To be specific, long-afterglow phosphor or long-afterglow phosphor/semiconductor composite can be used as a photocatalyst to simultaneously promote the photoredox processes and store extra photoexcited charges in the trapping states upon light irradiation. When the light illumination terminates, a gradual release of the charges from trapping states occurs in long-afterglow phosphor, which can continuously spur photoredox reactions under the dark environment and even maintains the photocatalysis around the clock. In this work, we comprehensively reviewed the recent advances of long afterglow phosphor based round-the-clock photocatalysts in environmental pollutant elimination. Meanwhile, the inherent mechanism of long afterglow photocatalysis was discussed in depth. More importantly, the relationship between the improved long afterglow photocatalytic capability and the engineering of long afterglow system is correlated systematically. Finally, the ongoing challenges and future prospects for the mass production and commercial utilization of round-the-clock photocatalysts are analyzed and outlooked.