Solar Light Harvesting Research Articles

Ultrathin carbon-coated Fe-TiO2-x nanostructures for enhanced photocatalysis under visible-light irradiation

Extending solar-light harvesting regions and improving charge separation are contributing to high-performance semiconductor photocatalysis. In this work, ultrathin carbon-coated Fe-TiO2-x nanostructures were prepared via one-pot calcination strategy for tetracycline degradation under visible-light irradiation. The experimental results showed that the carbon-coated Fe-TiO2-x composites displayed remarkably enhanced visible-light harvesting, and the forbidden band width droped to 2.60 eV. In addition, the transient photocurrent responses and electrochemical impedance spectra indicated the highest charge separation and lowest interfacial migration resistance of carbon-coated Fe-TiO2-x-3% composite, and the fluorescence emission spectra and linear sweep voltammetry curves also supported these above findings. The carbon-coated Fe-TiO2-x-3% sample showed the best photocatalytic performance with a rate constant of 0.02512 min−1 towards tetracycline degradation, approximately 3.02 times that of commercial TiO2, mainly attributed to the formation of Fe doping, oxygen vacancies, and relatively high surface areas.

Three-phase co-assembly of compositionally tunable WO3/TiO2 inverse opal photoelectrodes

Heterostructured WO3/TiO2 photonic crystal films in the form of three-dimensional macroporous inverse opals were developed by single-step, three-phase co-assembly of colloidal templates with water soluble precursors enabling simultaneous growth of both metal oxides into a firmly interconnected periodic pore framework whose skeletal walls consisted of uniformly distributed nanoscale type II WO3-TiO2 heterojunctions. A marked size- and composition-dependence of the binary WO3/TiO2 inverse opal properties was evidenced by controlling the W/Ti molar ratio and macropore diameter that allowed Fermi level and photonic band gap engineering according to optical and photoelectron spectroscopies supplemented by electrochemical measurements. Compositional tuning along with the reduction of WO3 nanocrystallite size and the concomitant W5+ defect growth with increasing TiO2 phase content were explored for the optimization of photocurrent generation by WO3/TiO2 inverse opal photoanodes combining reduced charge carrier recombination and optimal slow light trapping. One step co-assembly of mixed metal oxides is concluded as a promising route for the development of heterostructured inverse opal networks with tailored electronic properties and improved solar light harvesting for photo-induced applications.

Cu2(OH)2CO3 clusters modified MoS2@Ag2S heterojunctions for efficient photocatalytic pollutant degradation and hydrogen evolution

• Cu 2 (OH) 2 CO 3 clusters modified MoS 2 /Ag 2 S heterojunctions were constructed firstly. • Efficient methyl orange photodegradation and hydrogen evolution activity was achieved. • Reaction mechanism regarding to the high activity was proposed. In this report, Cu 2 (OH) 2 CO 3 -MoS 2 @Ag 2 S composites were constructed by combining with ions exchange reaction and precipitation method. The results showed that the MoS 2 microflowers were coated by the Ag 2 S nanoparticles. The as-prepared Cu 2 (OH) 2 CO 3 -MoS 2 @Ag 2 S composites exhibited the highest rate constant for Methyl Orange(MO) degradation (14.17x10 -3 min -1 ) and H 2 evolution (1.488mmol/g/h) under visible light irradiation, respectively, which is 20.5 and 4.7 times higher than that of MoS 2 . The enhanced MO degradation and H 2 evolution performance of Cu 2 (OH) 2 CO 3 -MoS 2 @Ag 2 S system is attributed to: 1) The intimate contact between Ag 2 S and MoS 2 is beneficial to charge transfer; 2) Efficient solar light harvesting of Ag 2 S on the surface of MoS 2 microflowers; 3) Cu 2 (OH) 2 CO 3 clusters served as photogenerated electrons traps further promote the separation of photogenerated charge carriers. The results of trapping experiment revealed that e - and h + acted as key roles in the process of photocatalytic MO degradation and water splitting. Our research provides great potential in constructing highly efficient heterojunction photocatalysts in environment and energy issues.

High-efficiency liquid luminescent solar concentrator based on CsPbBr3 quantum dots.

The performance degradation is still a challenge for the development of conventional polymer luminescent solar concentrator (LSC). Liquid LSC (L-LSC) may be an alternative due to polymerization-free fabrication. Here, we have prepared a CsPbBr3 quantum dots (QDs)-based L-LSC by injecting the QDs solution into a self-assembly quartz glass mold. The as-fabricated L-LSC performance is evaluated by optical characterization and photo-electrical measurement. The external quantum efficiency of the L-LSC is up to 13.44%. After coupling the commercial solar cell, the optimal optical efficiency reaches 2.32%. These results demonstrate that L-LSC may provide a promising direction for advanced solar light harvesting technologies.

Merging molecular catalysts and metal-organic frameworks for photocatalytic fuel production.

In the effort to generate sustainable clean energy from abundant resources such as water and carbon dioxide, solar fuel production-the combination of solar-light harvesting and the generation of efficient chemical energy carriers-by artificial molecular photosystems is very attractive. Molecular constituents that display attractive features for chemical energy conversion (such as high product selectivity and atom economy) have been developed, and their interfacing with host materials has enabled recyclability, controlled site positioning, as well as access to fundamental insights into the catalytic mechanism and environment-governed selectivity. Among the wide variety of supports, metal-organic frameworks (MOFs) possess valuable characteristics (such as their porosity and versatility) that can influence the reaction environment and material architecture in a unique fashion. Here we highlight the various existing synthetic strategies to graft molecular complexes such as catalysts and photosensitizers onto MOFs for solar fuel production. The opportunities and limitations of one-pot and stepwise approaches are critically assessed, and the resulting materials are discussed based on their photocatalytic performances and the practical applicability of selected examples.

DFT crystal and electronic structure of the direct bandgap Cu(1-x)NaxPF6: (x = 0.125n, n = 1–7)

DFT study on the crystal and electronic structure of the hexafluorophosphates Cu(1-x)NaxPF6 (x = 0.125n, n = 1–7) is presented. Both parent compounds CuPF6 and NaPF6 constituting the co-crystals have the same (FCC) spatial symmetry, very similar lattice constants (Δa = 0.017 Å), and according to periodic PBE density functional computations possess direct electronic bandgaps of 0.82 eV and 8.01 eV, respectively. Geometry optimization of the co-crystals Cu(1-x)NaxPF6 (x = 0.125n, n = 1–7) retain FCC symmetry. All the resulting electronic bandgaps are direct. Their values are intermediate between those of the parent compounds falling into the range from 0.97 eV (Cu0.875Na0.125PF6) to 2.22 eV (Cu0.125Na0.875PF6). All the compounds feature very small hole velocities. In contrast, electron velocities are high varying from 2.05*105 m/s (Cu0.875Na0.125PF6) to 1.12*105 m/s (Cu0.125Na0.875PF6) and showing descending trend as the content of sodium in the co-crystals increases. Taking into account the values of direct electronic bandgaps and presumed poor solubility in water the co-crystals seem good candidates for solar light harvesting applications.

Solar light harvesting nanomaterial (BaZrS3) for photocatalytic activity and OER reaction

The trend to use highly efficient and low cost multinary metal chalcogenides (MMCs) in the field of electrochemical and photocatalytic degradation of dyes increases day by day due to their narrow band gaps. Herein, BaZrS3 (BZS) nanomaterial is synthesized via hydrothermal route. XRD spectra with TEM and EDX results reveal that synthesized nanomaterial is well crystallized with single phase orthorhombic structure. UV–visible spectroscopy reveals its optical properties. Band gap of synthesized nanomaterial is 2.3 eV. Electrocatalytic oxygen evolution reaction (OER) and photocatalytic activity of prepared BZS has been studied by degrading the textile dye Congo red (CR) under direct sunlight. The electrochemical studies for OER reveal low value of overpotential of 312 mV with small Tafel slope (60mV/dec) at current density of 10 mA/cm2. Our synthesized material also shows high stability towards OER. The removal of CR by BZS after adsorption-desorption equilibrium is 70.96%. CR dye was adsorbed onto the surface of BaZrS3 and its adsorption phenomenon is related to its high specific surface area. The degradation efficiencies of 50 ppm, 60 ppm, 70 ppm and 100 ppm CR solutions are 95.34%, 92.47%, 87.80%, 70.43% in 30 min under solar irradiation, respectively.

Banana peel biowaste-derived carbon composited with Zn(O,S) for solar-light photocatalytic hydrogen generation

Banana peels-derived porous carbon has been synthesized with urea and potassium carbonate mixture and annealed at 700 ͦ C to decrease the size of carbon particles. The as-prepared carbon is composited with Zn(O,S) to form Zn(O,S)/C with different carbon contents of 1, 2.5, and 5 wt%. All the nanocomposites are identified with XRD, SEM, Raman, TEM, XPS, FTIR, and EPR analyses. The optical and electrochemical properties are also analyzed with DRS, Tauc plot, PL, EIS, TPC, MS, and CV measurements. Furthermore, the amounts of generated hydrogen gas are evaluated in the presence of Zn(O,S), ZC-1, ZC-2.5, and ZC-5 nanocomposites under simulated solar light irradiation. ZC-2.5 with an appropriate amount of banana peels carbon generates 9232 μmol/g in a 5-h photocatalytic reaction. The HER rate is enhanced by 1.7 times compared to pristine Zn(O,S). Incorporating low-cost banana peels carbon improves the separation between photogenerated electron and hole as the active site of carbon in ZC-2.5 attract the electron for hydrogen reduction. In addition, the generated Vo sites on Zn(O,S) during the photocatalytic reaction also increase the water and alcohol oxidation to scavenger the generated holes. This work designed a simple catalytic system with low-cost and environmentally-friendly material to provide an alternative energy source by harvesting solar light energy.

Glare-Free Airport-Based Photovoltaic System via Optimization of Its Azimuth Angle

Photovoltaic modules and systems (PVs) play an important role in achieving self-sustainable airports. In particular, airport-based PVs (A-PVs) have access to their full potential because airports are typically located in open spaces. However, the reflection of solar light by A-PVs’ front glass is unavoidable and may cause an accident due to solar glare (SG). In this study, we theoretically calculated the risk of SG from A-PVs depending on their azimuthal installation orientation (θPV) and derived a general design rule for minimizing the SG. The simulation reveals that the SG from A-PVs facing the runway and potential flight path causes after-images in pilots and ground workers throughout the year (>800 h/year). On the other hand, modifying their θPV, facing opposite runways and flight paths, significantly reduces the SG (<1 h/year) by reflecting the incident light outside the aircraft route. Although the θPV is not southward, their annual energy generation with an optimized θPV decreases by only 5–7% compared with A-PVs facing southward. This universal design approach is verified at four other airports, confirming the model’s validity. We believe our study will contribute to more solar light harvesting at airports without glare hazards.

Standard Method for the Determination of the Photocatalytic Activity of Titanium Dioxide TiO2 in a Black Body Reactor

Synthesis of semiconductors to be used as photocatalysis, solar fuels attracts a wide attention since semiconductors photocatalyst are the most effective techniques to harvest solar light for environmental remediation. To determine the activity of a semiconducting photocatalyst is by imploying a black body photoreactor,where is the reaction rate defined as the converted amount of a probe molecule per unit time (dn/dt).measuring the reaction rate of a probe compound with the same type of photoreactor to compare the activities of photocatalysts under identical irradiation conditions is a very general way. The black body like a reactor is a new practical application to measure the quantum yields of photochemical reactions (Φ) in liquid-solid heterogeneous systems. One of the most major advantage of this new method, it is too simple to determine the photocatalytic activity of a photocatalysts such as the TiO2 as long as the fraction of the reflected and transmitted light are negligible due to the reactor geometry and high optical density of the heterogeneous systems. The quantum yields of the hetrogeneous system is a direct reaction since there is a lack of reliable experimental methods which make the determination at any photocatalytic laboratories very easy. The quantum yields are defined as the number of molecules of a given reactant per photon of light absorbed by photocatalyst at a given wavelength.

Interstitial nitrogen-induced efficiency alcohol oxidation over heterogeneous N–CoMn2O4 catalyst under visible-light

Developing highly efficient and recyclable photocatalysts through harvesting solar light as energy is crucial to oxidation for industrial implementation, especially for simple transition metal oxidic catalysts without precious/heavy/rare metal dopants. Herein, we like to report the use of nitrogen-doped CoMn2O4 oxide (N–CoMn2O4) as a heterogeneous catalyst for efficient oxidation of various alcohols such as p/m/o-methyl-substituted aromatic alcohols, p-substituted aromatic alcohols including electron-donating and electron-withdrawing substituents, heterocycle-based alcohols and secondary aromatic alcohols to the corresponding aldehydes/ketones, under visible light (>420 ​nm) illumination and mild condition of oxygen as oxidant and room temperature. The relation of various Co-based oxides to their catalytic performance was studied. It is shown that the Co2+ species in N–CoMn2O4, obviously increased by the doping of nitrogen, are acted as catalytic active species coupled with the synergistic effect between Co and Mn species for the enhanced visible-light selective oxidation of alcohols to aldehydes. A plausible catalytic mechanism is proposed basis of control experiments and published studies, which suggests that this oxidation process probably occurs on Co2+ sites via an ionic reactive oxygen species pathway and 1O2 and O2·− species are the reactive oxygen species. This simple transition metal oxide-catalyzed aerobic oxidation provides a green alternative for the manufacture of aldehydes/ketones from alcohols.

Improving the Holographic Recording Characteristics of a Water-Resistant Photosensitive Sol–Gel for Use in Volume Holographic Optical Elements

Continual improvements to holographic recording materials make the development of volume holographic optical elements increasingly more attainable for applications where highly efficient, lightweight diffractive optical elements can replace conventional optics. A fast-curing, water resistant photosensitive sol–gel capable of volume holographic recording has recently drawn attention for its extreme environmental and physical robustness, in particular its water/moisture and scratch resistance. However, to date, the refractive index modulation has been limited. While water-resistant properties are invaluable in the face of the weathering which many practical systems for outdoor applications will endure, high refractive index modulation is also important in order to facilitate high diffraction efficiency holograms recorded in relatively thin layers. Lower grating thickness ensures a large angular and wavelength range of operation-properties that are critical for many applications of holographic optical elements such as solar light harvesting, optical displays and illumination management. For any application where low-cost mass production is envisaged, sensitivity/writing speed is also a crucial factor. In this research, we studied the recording properties of these water-resistant photosensitive sol–gel layers at two different recording wavelengths (532 and 476 nm) and investigated methods for improving these properties. We report more than two-fold improvement of the refractive index modulation from 1.4×10−3 to 3.3×10−3 in layers of thickness ranging from 40–100 μm and more than an order of magnitude increase in photosensitivity/recording speed through better matching between recording wavelength and layer absorption, chemical alterations and thermal post-processing techniques.

Interplay between charge separation and hole back transfer determines the efficiency of non-fullerene organic solar cells with low energy level offset

Organic bulk heterojunction solar cells with electron acceptors based on small donor-acceptor type molecules show record efficiencies mainly due to their long wavelength absorption, which enables efficient harvesting of solar light and, thus, causes high current density. Meanwhile, relative positions of HOMO and LUMO levels of donor and acceptor materials determine the open circuit voltage. Here, we apply ultrafast transient absorption and transient luminescence techniques together with specially-designed modelling technique to address charge carrier generation and recombination dynamics in detail. We demonstrate the importance of careful adjustment of the HOMO and LUMO levels, as their positions determine formation and recombination rates of interfacial charge transfer (CT) states. An insufficient donor and acceptor LUMO level offset, lower than ∼300 meV, leads to slow and inefficient CT state formation, while an offset of the HOMO level below ∼100 meV leads to fast CT state recombination, which we attribute to the back transfer of a hole from the donor to the acceptor. • CT state formation was investigated by ultrafast transient techniques and modelling. • ∼300 meV LUMO offset is required for efficient CT state generation. • > 100 meV HOMO offset is sufficient for ultrafast hole transfer. • Low HOMO offset opens a loss channel via the back transfer of an electron.

Quantum Dot-based Luminescent Solar Concentrators Fabricated through the Ultrasonic Spray-Coating Method.

Luminescent solar concentrators (LSCs) are a class of wave-guiding devices that can harvest solar light and concentrate it to targeted smaller areas. When coupled with photovoltaic devices (PVs), LSCs hold the potential to be integrated into various application setups, especially for building facade integration toward net-zero-energy buildings. Developing reliable LSC fabrication methods with easy scalability, high adaptability, and device controllability has been an important research topic. In this work, we report an ultrasonic nebulization-assisted spray deposition technique to fabricate quantum dot (QD)-based LSCs (QD-LSCs). This method allows for the production of high-performance QD-LSCs with different device dimensions and geometries. In addition, the quality of the QD thin-film coating layer is relatively independent of the concentration and volume of the coating QD ink solution, allowing for deliberate programming and performance optimization of the resulting QD-LSC devices. We anticipate that this ultrasonic spray coating method can be widely applied to the manufacturing of high-quality LSC devices that are integrable to various applications.

Purposefully designing Co-S-codoping in hierarchical BiOCl architectures and elucidating the mechanism for enhanced visible-light-driven photocatalytic activity

Simultaneously doping metal and nonmetal species into BiOCl photocatalysts is an efficient way to tailor the valence band and conduction band for enhanced both solar light harvesting and photocharge separation. However, the investigation on metal-nonmetal codoping of BiOCl photocatalysts is still less so far. Herein, the codoping of Co and S species into hierarchical BiOCl architectures (denoted as BOC-Co-S) is realized by a simple one-pot hydrothermal method. The as-prepared BOC-Co-S samples demonstrated remarkably high-efficient visible-light-driven photocatalytic performances toward the degradation of Rhodamine B and tetracycline compared with the Co-doped BiOCl, S-doped BiOCl and pure BiOCl samples. The improved photodegradation activities of BOC-Co-S samples can be ascribed to the increased solar light harvesting, efficient charge separation and sufficient activity sites derived from Co-S codoping. This study might provide a promising strategy to further explore simple and economic organic-free routes for the development of high-active bismuth oxyhalides-based photocatalysts.

Synthesis and Photophysics Characterization of Boronic Styril and Distyryl BODIPYs for Water-Based Dye-Sensitized Solar Cells.

In this study, two boronic acid BODIPYs are obtained through a microwave-assisted Knoevenagel reaction. The aim is to use them for the first time as dyes in a photosensitized solar cell (DSSC) to mimic chlorophyll photosynthesis, harvesting solar light and converting it into electricity. The microwave-assisted Knoevenagel reaction is a straightforward approach to extending the molecular conjugation of the dye and is applied for the first time to synthesize BODIPY’s boronic acid derivatives. These derivatives have proved to be very useful for covalent deposition on titania. This work studies the photo-physical and electrochemical properties. Moreover, the photovoltaic performances of these two new dyes as sensitizers for DSSC are discussed. Experimental data show that both dyes exhibit photosensitizing activities in acetonitrile and water. In particular, in all the experiments, distyryl BODIPY was more efficient than styryl BODIPY. In this study, demonstrating the use of a natural component as a water-based electrolyte for boronic BODIPY sensitizers, we open new possibilities for the development of water-based solar cells.

An integrated Si photocathode with lithiation-activated molybdenum oxide nanosheets for efficient ammonia synthesis

As an alternative to the conventional industrial Haber-Bosch process, photoelectrochemical (PEC) routes that are powered by renewable solar energy hold great promise for N2 reduction reaction (NRR) towards NH3 synthesis at ambient conditions. However, great challenges remain in promoting NH3 production rate for the PEC NRR devices, especially with the earth-abundant catalysts. Here we report an integrated LixMoO3/n+np+-Si photocathode could achieve an unprecedented PEC NH3 yield rate of 8.7 μg cm−2 h−1, which is among the highest PEC NRR systems ever reported. With an optically and electrocatalytically decoupled configuration, the integrated PEC photocathode could harvest the sunlight sufficiently and simultaneously promote the catalytic kinetics, thus leading to the improved NH3 synthesis. More importantly, such high PEC NRR performance is derived from earth-abundant elements without precious noble metals. Verified by the electrochemical experiments and density functional theory (DFT) calculations, the lithiation strategy gives rise to dramatic structural distortion accompanying the abundant oxygen vacancies and Mo5+ ions, which results in faster NRR kinetics and activates inert MoO3 into efficient LixMoO3 electrocatalyst towards NH3 synthesis. This work holds great promise in constructing monolithic PEC device to directly harvest solar light for artificial ammonia photosynthesis.

Plasmon Induced Near‐Infrared Active Photocatalysts: A Review

AbstractIn the recent past, near‐infrared (NIR) active photocatalysts have received tremendous research attention to harvest solar NIR energy as the solar spectrum carries abundant NIR light. Again, plasmonic materials with their intense surface plasmon resonance (SPR) activity in the visible and NIR range can be a suitable candidate for NIR active photocatalysis. However, the ultrafast energy relaxation of the plasmon‐generated hot electrons restricts their application in photocatalysis. In this review, the recent progress in the plasmon‐induced NIR active photocatalysis has been summarized. Particular emphasis has been given to divulging the mechanism to NIR modulation of localized surface plasmon resonance (LSPR), LSPR intensification, LSPR induction mechanism in non‐noble metals, and suitable technologies to separate the photogenerated hot electrons efficiently and their exploration in photocatalytic reactions. The drawbacks, possible solutions, and potential of non‐noble metal plasmonic photocatalysis have been discussed in detail. Finally, the review ends with concluding remarks and possible prospects of plasmonic photocatalysts. It is believed that this review will inspire researchers to rationally design broad‐spectrum (UV–vis–NIR) active photocatalysts to harvest solar light efficiently.

(Invited) Discovering Bottlenecks and Opportunities in Hybrid Solar Light Harvesting Systems By Ultrafast X-Ray Spectroscopy

A prerequisite for advancing hybrid solar light harvesting systems is a comprehensive understanding of photoinduced electronic dynamics across a wide range of spatial and temporal scales. Time-resolved spectroscopy techniques in the optical domain have proven instrumental in identifying critical timescales of fundamental processes, such as interfacial charge transfer, charge migration, and carrier lifetimes, which are intimately linked to a system's performance. New light source and instrument developments open opportunities to extend such studies into the X-ray regime. Due to their inherent elemental specificity and sensitivity to local electronic environments, time-domain X-ray spectroscopy techniques are uniquely suited to gain a microscopic picture of dynamics from well-defined reporter sites within often complex nanoscale light harvesting architectures. We will present new insights into fundamental photoinduced dynamics in several archetypical heterostructures based on femtosecond and picosecond time-resolved X-ray photoemission spectroscopy (TRXPS).The photoinduced transient charge redistribution in the model hybrid system of nanoporous zinc oxide (ZnO) sensitized by ruthenium bipyridyl chromophores is probed independently from the viewpoints of the molecular electron donor and the semiconductor acceptor.[1] Charge injection from the chromophore into the semiconductor is found to proceed via a transiently populated interfacial charge transfer (ICT) complex on an overall timescale of ~300 ps. Our results show that, even after release from the ICT states into the ZnO conduction band, the injected electrons remain localized within less than 6 nm from the interface, due to enhanced downward band-bending by the photo-injected charge carriers. This spatial confinement suggests that light-induced charge generation and transport in nanoscale ZnO photocatalytic devices proceeds predominantly within the defect-rich surface region, which may lead to enhanced surface recombination and explain their lower performance compared to titanium dioxide (TiO2)-based systems. The quantitative nature and surface sensitivity of TRXPS also provides direct access to the spatial separation of the holes remaining on the bipyridyl chromophores after charge injection from the semiconductor surface with sub-nm precision.Complementary femtosecond and picosecond TRXPS studies of photoinduced dynamics in copper-phthalocyanine(CuPc)-C60 heterojunctions provide a deeper understanding of both exciton migration pathways toward the interface as well as the absolute efficiency by which ICT states dissociate into separate charges.[2] The measurements reveal surprisingly efficient charge generation from triplet excitons and from the lowest lying ICT states, both of which were previously believed to be inactive during light-to-charge conversion.Photoinduced charge transfer dynamics between spherical gold nanoparticles (AuNPs) and a nanoporous film of TiO2 is monitored by picosecond TRXPS, providing direct access to the absolute photon-to-charge conversion efficiency and subsequent electron-hole recombination dynamics.[3] Preliminary results will be presented for the extension of the measurements into the ambient pressure regime, taking a first step toward the study of photoinduced interfacial chemistry by TRXPS in this model system for nanoplasmonic light harvesting applications.[1] S. Neppl et al., “Nanoscale Confinement of Photo-Injected Electrons at Hybrid Interfaces”, J. Phys. Chem. Lett. 12, 11951 (2021).[2] F. Roth et al., “Direct observation of charge separation in an organic light harvesting system by femtosecond time-resolved XPS”, Nat. Commun. 12, 1196 (2021).[3] M. Borgwardt et al., “Photoinduced Charge Carrier Dynamics and Electron Injection Efficiencies in Au Nanoparticle-Sensitized TiO2 Determined with Picosecond Time-Resolved X-ray Photoelectron Spectroscopy”, J. Phys. Chem. Lett. 11, 5476 (2020). Figure 1

Constructing Direct Z-Scheme Heterostructure by Enwrapping ZnIn2 S4 on CdS Hollow Cube for Efficient Photocatalytic H2 Generation.

Rational design hybrid nanostructure photocatalysts with efficient charge separation and transfer, and good solar light harvesting ability have critical significance for achieving high solar‐to‐chemical conversion efficiency. Here a highly active and stable composite photocatalyst is reported by integrating ultrathin ZnIn2S4 nanosheets on surface of hollow CdS cube to form the cube‐in‐cube structure. Experimental results combined with density functional theory calculations confirm that the Z‐scheme ZnIn2S4/CdS heterojunction is formed, which highly boosts the charge separation and transfer under the local‐electric‐field at semiconductor/semiconductor interface, and thus prolongs their lifetimes. Moreover, such a structure affords the highly enhanced light‐harvesting property. The optimized ZnIn2S4/CdS nanohybrids exhibit superior H2 generation rate under visible‐light irradiation (λ ≥ 420 nm) with excellent photochemical stability during 20 h continuous operation.