Stacking Engineering of Semiconductor Heterojunctions on Hollow Carbon Spheres for Boosting Photocatalytic CO2 Reduction

Reinforcing Cd-S bonds through morphology engineering for enhanced intrinsic photocatalytic stability of CdS

Effectively mitigating photocorrosion is paramount for achieving high-efficiency and sustainable hydrogen production through photocatalytic water splitting over CdS. In this work, we develop a morphology engineering strategy with adjustable Cd-S bond energy through a simple chemical bath deposition method to synthesize novel hollow hemispherical CdS (H-CdS). The morphologic structure CdS can be precisely controlled by adjusting the reaction temperature, time and pH. Compared with common morphologies of CdS, H-CdS, with its reinforced Cd-S bonding, exhibits not only improved photocatalytic hydrogen evolution activity (20.04 mmol/g/h) but also exceptional resistance to photocorrosion, resulting in outstanding cyclic stability even without the aid of cocatalysts or the introduction of other semiconductors. Comprehensive characterizations reveal that the photocorrosion resistance of H-CdS stems from the high Cd-S bond strength. Moreover, in-situ infrared spectroscopy confirms alterations in the properties and activities of the various CdS morphologies after photocatalytic reaction due to photocorrosion. We thoroughly describe the relationship among morphology, surface energy, bond energy and photocorrosion resistance. Our findings present a novel strategy for mitigating the photocorrosion of CdS and offer valuable insights for future research on CdS photocatalysts aimed at stable water splitting.

Synergistic manipulation of sulfur vacancies and palladium doping of In2S3 for enhanced photocatalytic H2 production

In this study, a simple one-pot synthesis process is employed to introduce Pd dopant and abundant S vacancies into In2S3 nanosheets. The optimized Pd-doped In2S3 photocatalyst, with abundant S vacancies, demonstrates a significant enhancement in photocatalytic hydrogen evolution. The joint modification of Pd doping and rich S vacancies on the band structure of In2S3 result in an improvement in both the light absorption capacity and proton reduction ability. It is worth noting that photogenerated electrons enriched by S vacancies can rapidly migrate to adjacent Pd atoms through an efficient transfer path constructed by Pd-S bond, effectively suppressing the charge recombination. Consequently, the dual-defective In2S3 shows an efficient photocatalytic H2 production rate of 58.4 ± 2.0 μmol·h-1. Additionally, further work has been conducted on other ternary metal sulfide, ZnIn2S4. Our findings provide a new insight into the development of highly efficient photocatalysts through synergistic defect engineering.

An environmentally friendly chitosan-loaded BiOCOOH/BiYO3 photocatalyst for efficient photocatalytic degradation of tetracycline

In this work, the photocatalyst BiOCOOH/BiYO3/Chitosan (CS) was prepared by using CS as the carrier and adsorbent. The performance of the material was studied through the photocatalytic degradation of tetracycline (TC) in water. Theoretical calculations and experiments demonstrate that the formation of BiOCOOH/BiYO3 heterojunctions improves the separation of photogenerated carriers and the absorption of visible light by the material. The introduction of CS improves the difficulties in material recovery, demonstrating exceptional degradation ability for TC under the action of adsorption and photocatalysis. Adsorption kinetics studies indicate that the adsorption of TC by BiOCOOH/BiYO3/CS fits the pseudo-second-order model better, while the adsorption at different concentrations of TC is more suitably described by the Freundlich isotherm model. The synthesis of BiOCOOH/BiYO3/CS was confirmed by the analysis of XRD, XPS, and FTIR. UV-vis DRS showed that the synthesis of BiOCOOH/BiYO3/CS broadened the range of light absorbed by the material. The testing results of PL and transient photocurrent density indicate that BiOCOOH/BiYO3 exhibits a higher efficiency in separating photogenerated charge carriers. After 5 cycles of reuse, the degradation efficiency can still reach 90 % of the initial efficiency, indicating that CS-based photocatalytic composite catalysts have practical application potential in the field of water pollution treatment.

Enhancing the Lewis acidity of single atom Tb via introduction of boron to achieve efficient photothermal synergistic CO2 cycloaddition

Nowadays, it is becoming increasingly urgent to lower the escalating carbon dioxide (CO2) to reduce greenhouse effect. Fortunately, it is an ideal strategy by using the inexhaustible solar energy as the driving force to manipulate the cycloaddition reaction, the atomic efficiency of which is 100 %. This work represents the first attempt on utilization of rare-earth metal Tb with atomic dispersion, and the structure of Tb coordinated with 4 N-atoms and 2B-atoms was constructed on interconnected carbon hollow spheres. The introduction of electron-deficient B reduces the electron density of Tb, thereby boosting Lewis acidity and promoting the occurrence of ring-opening reaction. The mechanism exploration enunciates that TbN4B2/C is a photothermal synergistic catalyst, the combined action of photogenerated electrons and strong Lewis acidic site of Tb reduces the free energy of the rate-determining step, and then improving the yield of cyclic carbonate up to 739 mmol g-1h-1.

In Situ Construction of Hollow Coral-Like Porous S-Doped g-C3N4/ZnIn2S4 S-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution

The rational design of visible-light-responsive catalysts is crucial for converting solar energy into hydrogen energy to promote sustainable energy development. In this work, a C─S─C bond is introduced into g-C3N4 (CN) through S doping. With the help of the flexible C─S─C bond under specific stimuli, a hollow coral-like porous structure of S-doped g-C3N4 (S-CN) is synthesized for the first time. And an S-doped g-C3N4/ZnIn2S4 (S-CN/ZIS) heterojunction catalyst is in situ synthesized based on S-CN. S0.5-CN/ZIS exhibits excellent photocatalytic hydrogen evolution (PHE) efficiency (19.25 mmol g-1 h-1), which is 2.7 times higher than that of the g-C3N4/ZnIn2S4 (CN/ZIS) catalyst (8.46 mmol g-1 h-1), with a high surface quantum efficiency (AQE) of 34.43% at 420 nm. Experiments and theoretical calculations demonstrate that the excellent photocatalytic performance is attributed to the larger specific surface area and porosity, enhanced interfacial electric field (IEF) effect, and appropriate hydrogen adsorption Gibbs free energy (ΔGH*). The synergistic effect of S doping and S-scheme heterojunction contributes to the above advancement. This study provides new insights and theoretical basis for the design of CN-based photocatalysts.

Amorphous ZnSnOx Hollow Spheres Enable Highly Efficient CO2 Reduction

Carbon dioxide (CO2) adsorption and electron transport play an important role in CO2 reduction reaction (CO2RR). Herein, we have demonstrated a new class of diverse hollow ZnSnOx (ZSO) through the amorphization of hydroxides to enhance CO2 adsorption and accelerate electron transport. The amorphization is occurred by calcination process, as indicated by Fourier transform infrared spectroscopy and Raman spectra. In particular, the ZnSnOx hollow spheres (ZSO HSs) achieve a high Faradaic efficiency (FE) of HCOOH up to 92.7 % at best, outperforming the commercial ZSO (Comm. ZSO, 85.7 %). ZSO HSs also exhibit durable stability with negligible activity decay after 10 h of successive electrolysis. In-situ attenuated total reflectance infrared absorption spectroscopy further reveals strong adsorption of CO2 and rapid intermediate configuration transformation in amorphous ZSO HSs. This work demonstrates the practical application of ZSO for CO2RR and provides a new insight to create efficient CO2RR electrocatalysts.

Construction of an In2O3/Bi2S3 Z-Scheme Heterojunction for Enhanced Photocatalytic CO2 Reduction

Photocatalytic conversion of CO2 to hydrocarbon fuel is a potential strategy to solve energy shortage and mitigate the greenhouse effect. Here, direct Z-scheme heterojunction photocatalysts (In2O3/Bi2S3) without an electron mediator are prepared by a simple hydrolysis method. The In2O3/Bi2S3 composite photocatalysts show greatly boosted photoactivity on CO2 conversion to CO compared with the pristine In2O3 and Bi2S3. The highest CO evolution rate of 2.67 μmol·g-1·h-1 is achieved by In2O3/Bi2S3-3, without any sacrificial agent or cocatalyst, which is about 3.87 times that of In2O3 (0.69 μmol·g-1·h-1). The boosted photocatalytic performance of In2O3/Bi2S3 composite catalysts can be ascribed to the establishment of a Z-scheme heterojunction, improving the photoabsorption and facilitating charge separation and transfer. This study provides a reference for designing and fabricating high-efficiency Z-scheme heterojunction photocatalysts for photocatalytic CO2 reduction.

Electronic Structure Design of Transition Metal-Based Catalysts for Electrochemical Carbon Dioxide Reduction

With the increasingly serious greenhouse effect, the electrochemical carbon dioxide reduction reaction (CO2RR) has garnered widespread attention as it is capable of leveraging renewable energy to convert CO2 into value-added chemicals and fuels. However, the performance of CO2RR can hardly meet expectations because of the diverse intermediates and complicated reaction processes, necessitating the exploitation of highly efficient catalysts. In recent years, with advanced characterization technologies and theoretical simulations, the exploration of catalytic mechanisms has gradually deepened into the electronic structure of catalysts and their interactions with intermediates, which serve as a bridge to facilitate the deeper comprehension of structure-performance relationships. Transition metal-based catalysts (TMCs), extensively applied in electrochemical CO2RR, demonstrate substantial potential for further electronic structure modulation, given their abundance of d electrons. Herein, we discuss the representative feasible strategies to modulate the electronic structure of catalysts, including doping, vacancy, alloying, heterostructure, strain, and phase engineering. These approaches profoundly alter the inherent properties of TMCs and their interaction with intermediates, thereby greatly affecting the reaction rate and pathway of CO2RR. It is believed that the rational electronic structure design and modulation can fundamentally provide viable directions and strategies for the development of advanced catalysts toward efficient electrochemical conversion of CO2 and many other small molecules.

Hollow Nanoreactors for Controlled Photocatalytic Behaviors: Fundamental Theory, Structure-Performance Relationship, and Catalytic Advantages

Hollow nanoreactors (HoNRs) have regarded as an attractive catalytic material for photocatalysis due to their exceptional capabilities in enhancing light harvesting, facilitating charge separation and transfer, and optimizing surface reactions. Developing novel HoNRs offers new options to realize controllable catalytic behavior. However, the catalytic mechanism of photocatalysis occurring in HoNRs has not yet been fully revealed. Against this backdrop, this review elaborates on three aspects: 1) the fundamental theoretical insights of HoNRs-driven photocatalytic kinetics; 2) structure-performance relationship of HoNRs to photocatalysis; 3) catalytic advantages of HoNRs in photocatalytic applications. Specifically, the review focuses on the fundamental theories of HoNRs for photocatalysis and their structural advantages for strengthening light scattering, promoting charge separation and transfer, and facilitating surface reaction kinetics, and the relationship between key structural parameters of HoNRs and their photocatalytic performance is in-depth discussed. Also, future prospects and challenges are proposed. It is anticipated that this review paper will pave the way for forthcoming investigations in the realm of HoNRs for photocatalysis.

Hollow carbon-based materials for electrocatalytic and thermocatalytic CO2 conversion

Electrocatalytic and thermocatalytic CO2 conversions provide promising routes to realize global carbon neutrality, and the development of corresponding advanced catalysts is important but challenging. Hollow-structured carbon (HSC) materials with striking features, including unique cavity structure, good permeability, large surface area, and readily functionalizable surface, are flexible platforms for designing high-performance catalysts. In this review, the topics range from the accurate design of HSC materials to specific electrocatalytic and thermocatalytic CO2 conversion applications, aiming to address the drawbacks of conventional catalysts, such as sluggish reaction kinetics, inadequate selectivity, and poor stability. Firstly, the synthetic methods of HSC, including the hard template route, soft template approach, and self-template strategy are summarized, with an evaluation of their characteristics and applicability. Subsequently, the functionalization strategies (nonmetal doping, metal single-atom anchoring, and metal nanoparticle modification) for HSC are comprehensively discussed. Lastly, the recent achievements of intriguing HSC-based materials in electrocatalytic and thermocatalytic CO2 conversion applications are presented, with a particular focus on revealing the relationship between catalyst structure and activity. We anticipate that the review can provide some ideas for designing highly active and durable catalytic systems for CO2 valorization and beyond.

Integration of ohmic junction and step-scheme heterojunction for enhanced photocatalysis

A novel and efficient photocatalyst, Cu2WS4/MoS2-Au plasmonic Step-scheme (S-scheme) heterojunction, was constructed for the first time and applied to remove environmental pollutants. Among all the prepared photocatalysts, the. Cu2WS4/MoS2-Au-5 exhibited the highest catalytic activity with an 89.1% reduction efficiency for Cr6+ and a 98.7% oxidation efficiency for Benzophenone-1 (BP-1) under visible light irradiation. The Cu2WS4/MoS2-Au photocatalyst exhibits stable performance and efficient photocatalytic activity due to effective charge separation, enhanced light absorption from localized surface plasmon resonance (LSPR) of gold nanoparticles, and the formation of an S-scheme heterojunction with strong oxidation-reduction capabilities. In addition, through analysis of experiments and theoretical calculations, it is speculated that the Cu2WS4/MoS2-Au follows a typical S-scheme photogenerated carrier transferring mechanism, which is verified by the finite difference time domain simulation, the free radical quenching experiments, the electron paramagnetic resonance analysis and the simulated charge density distribution. More importantly, the simulations of the work function and charge density distribution confirm the built-in electric field and the ohmic junction have been established at the interfaces between the Cu2WS4 and MoS2 (Cu2WS4/MoS2) as well as the interface between MoS2 and Au (MoS2-Au), respectively. The built-in electric field and ohmic junction enable efficient separation of photogenerated electrons and holes, ensuring the superior catalytic oxidation and reduction activities of the Cu2WS4/MoS2-Au photocatalyst. Finally, we propose a photocatalytic mechanism for the Cu2WS4/MoS2-Au plasmonic S-scheme heterojunction based on experimental results and simulated calculations. The research results of this study are significance for the development of the plasmonic S-scheme photocatalytic system.

Hollow Plasmonic P-Metal-N S-Scheme Heterojunction Photoreactor with Spatially Separated Dual Cocatalysts toward Artificial Photosynthesis

Semiconductor-based step-scheme (S-scheme) heterojunctions possess many merits toward mimicking natural photosynthesis. However, their applications for solar-to-chemical energy conversion are hindered by inefficient charge utilization and unsatisfactory surface reactivity. Herein, two synergistic protocols are demonstrated to overcome these limitations based on the construction of a hollow plasmonic p-metal-n S-scheme heterojunction photoreactor with spatially separated dual noble-metal-free cocatalysts. On one side, plasmonic Au, inserted into the heterointerfaces of CuS@ZnIn2 S4 core-shell nanoboxes, not only accelerates the transfer and recombination of useless charges, enabling a more thorough separation of useful ones for CO2 reduction and H2 O oxidation but also generates hot electrons and holes, respectively injects them into ZnIn2 S4 and CuS, further increasing the number of active carriers participating in redox reactions. On the other side, Fe(OH)x and Ti3 C2 cocatalysts, separately located on the CuS and ZnIn2 S4 surface, enrich the redox sites, adjust the reduction potential and pathway for selective CO2 -to-CH4 transformation, and balance the transfer and consumption of photocarriers. As expected, significantly enhanced activity and selectivity in CH4 production are achieved by the smart design along with nearly stoichiometric ratios of reduction and oxidation products. This study paves the way for optimizing artificial photosynthetic systems via rational interfacial channel introduction and surface cocatalyst modification.

One-Step Fabricated Sn0 Particle on S-Vacancies SnS2 to Accelerate Photoelectron Transfer for Sterling Photocatalytic CO2 Reduction in Pure Water Vapor Environment

Promoting the proton-coupled electron transfer process in order to solve the sluggish carrier migration dynamics is an efficient way to accelerate the photocatalytic CO2 reduction (PCR) process. Herein, through the reduction of Sn4+ by amino and sulfhydryl groups, Sn0 particles are lodged in S-vacancies SnS2 nanosheets. The high conductance of Sn0 particles expedites the collection and transport of photogenerated electrons, activating the surrounding surface of unsaturated sulfur (Sx 2- ) and thus lowering the energy barrier for generation of *COOH. Meanwhile, S-vacancies boost H2 O adsorption while Sx 2- increases CO2 adsorption, as demonstrated by density functional theory (DFT), obtaining a selectivity of 97.88% CO and yield of 295.06 µmol g-1 h-1 without the addition of co-catalysts and sacrificial agents. This work provides a new approach to building a fast electron transfer interface between metal particles and semiconductors, which works in tandem with S-vacancies and Sx 2- to boost the efficiency of photocatalytic CO2 reduction to CO in pure water vapor environment.

Increasing the Photocatalytic Hydrogen Generation Activity of CdS Nanorods by Introducing Interfacial and Polarization Electric Fields

Cadmium sulfide (CdS) is a photocatalyst widely used for efficient H2 production under visible light irradiation, due to its narrow bandgap and suitable conduction band position. However, the fast recombination of carriers results in their low utilization. In order to improve photocatalytic hydrogen production, it reports the successful introduction of metallic Cd and S vacancies on CdS nanorods (CdS NRs) by a facile in situ chemical reduction method, using a thermal treatment process. This procedure generates interfacial and polarization electric fields, that significantly improve the photocatalytic hydrogen production performance of CdS NRs in sodium sulfide and sodium sulfite aqueous solutions, under visible light irradiation (λ >420 nm). The introduction of these electric fields is believed to improve charge separation and facilitate faster interfacial charge migration, resulting in a significantly optimized catalyst, with a photocatalytic hydrogen evolution rate of up to 10.6 mmol-1  g-1  h-1 with apparent quantum efficiency (AQE) of 12.1% (420 nm), which is 8.5 times higher than that of CdS. This work provides a useful method to introduce metallic and S vacancies on metal sulfide photocatalysts to build local polarization and interfacial electric fields for high-performance photocatalytic H2 production.

Label-free "signal-off" PEC aptasensor for determination of kanamycin based on 3D nanoflower-like FeIn2S4/CdS Z-scheme heterostructures

Highly photoactive 3D nanoflower-like FeIn2S4/CdS heterostructures were synthesized by hydrothermal treatment and low-temperature cation exchange. The FeIn2S4/CdS displayed 14.5 times signal amplification in contrast to FeIn2S4 alone. It was applied as a photoactive substrate to construct a label-free photoelectrochemical (PEC) aptasensor for ultrasensitive determination of kanamycin (KAN). Under the optimal conditions, the constructed PEC aptasensor displayed a wide linear range (5.0 × 10-4 ~ 5.0 × 101 ng mL-1) and a low detection limit (S/N = 3) of 40.01 fg mL-1. This study provides some constructive insights for preparation of advanced photoactive materials and exhibits great potential for quantitative determination of antibiotics in foods and environmental samples.

Palladium particles dispersed on hollow structural support improve CO2 conversion

Herein, an effective Pd/NHS catalyst has been designed and facilely synthesized with extraordinary CO2 fixation performance, which is superior to that of Pd/NS catalysts, owing to the hollow structures facilitating mass transfer and product release.

Enhanced Interfacial Charge Transfer/Separation By LSPR-Induced Defective Semiconductor Toward High Co2 RR Performance

Solar-driven reduction of CO2 emissions into high-value-added carbonaceous compounds has been recognized as a sustainable energy conversion way. The high-efficiency charge separation and effective activation are the critical issues in the process. The local plasma effect of metal and the vacancy of semiconductors in the metal-semiconductor heterostructure can solve this issue extensively. Herein, an oxygen vacancy photocatalyst containing uniform Ag nanoparticles (Ag-20@Nb2 O5- x ) is designed, which exhibits an excellent reduction performance and the CO yield can reach 59.13 µmol g-1 with high selectivity. The carrier migration is accelerated and the activation of CO2 is facilitated by the local surface plasmon effect and oxygen vacancy. Moreover, the photocatalytic CO2 reduction mechanism is revealed based on the density functional theory and in situ technology in detail. This work provides an in-depth understanding of the design of more ingenious metal-semiconductor photocatalysts to achieve more efficient charge transfer.

Influence of Potassium-Based Activation on Adsorptive Properties of Carbon Spheres Modified with Iron(III) Citrate

Composites synthesized from iron(III) citrate and carbon spheres, and activated with potassium compounds were prepared and then characterized using XRD, SEM, and low-temperature nitrogen adsorption methods. The adsorption properties of the composites toward carbon dioxide were assessed using CO2 uptake measurement, as well as by measuring their selectivity toward carbon dioxide, given their further application as photocatalysts for the reduction of this gas. The effect of changing preparation conditions on the structural and adsorption properties of the material was assessed. The potential strength of such material is a synergistic effect between the high adsorption capacity related to the microporosity of carbon spheres combined with the catalytic properties of iron particles.

Regulating the Charge Migration in CuInSe2 /N-Doped Carbon Nanorod Arrays via Interfacial Engineering for Boosting Photoelectrochemical Water Splitting

Regulating the charge migration and separation in photoactive materials is a great challenge for developing photoelectrochemical (PEC) applications. Herein, inspired by capacitors, well-defined CuInSe₂ /N-doped carbon (CISe/N-C) nanorod arrays are synthesized by Cu/In-metal organic frame-derived method. Like the charge process of capacitor, the N-doped carbon can capture the photogenerated electron of CISe, and the strong interfacial coupling between CISe and N-doped carbon can modulate the charge migration and separation. The optimized the CISe/N-C photoanode achieves a maximum photocurrent of 4.28 mA cm^-2 at 1.23 V versus reversible hydrogen electrode (RHE) in neutral electrolyte solution under AM 1.5 G simulated sunlight (100 mW cm^-2 ), which is 8.4 times higher than that of the CuInSe₂ photoanode (0.51 mA cm^-2 ). And a benefit of the strong electronic coupling between CISe and N-doped carbon, the charge transfer rate is increased to 1.3-13 times higher than that of CISe in the range of 0.6-1.1 V versus RHE. The interfacial coupling effects on modulating the carrier transfer dynamics are investigated by Kelvin probe force microscopy analysis and density functional theory calculation. This work provides new insights into bulk phase carrier modulation to improve the performance of photoanode for PEC water splitting.

Embedding Plasmonic Metal into Heterointerface of MOFs-Encapsulated Semiconductor Hollow Architecture for Boosting CO2 Photoreduction

Coupling hollow semiconductor with metal-organic frameworks (MOFs) holds great promise for constructing high-efficient CO₂ photoreduction systems. However, energy band mismatch between them makes it difficult to exert their advantages to maximize the overall photocatalytic efficiency, since that the blockage of desirable interfacial charge transfer gives rise to the enrichment of photoelectrons and CO₂ molecules on the different locations. Herein, an interfacial engineering is presented to overcome this impediment, based on the insertion of plasmonic metal into the heterointerfaces between them, forming a stacked semiconductor/metal@MOF photocatalyst. Experimental observations and theoretical simulations validate the critical roles of embedded Au in maneuvering the charge separation/transfer and surface reaction: (i) bridges the photoelectron transfer from hollow CdS (H-CdS) to ZIF-8; (ii) produces hot electrons and shifts them to ZIF-8; (iii) induces the formation of ZIF-8 defects in promoting the CO₂ adsorption/activation and transformation to CO with low energy barriers. Consequently, the as-prepared H-CdS/Au@ZIF-8 with optimal ZIF-8 thickness exhibits distinctly boosted activity and superb selectivity in CO production as compared with H-CdS@ZIF-8 and other counterparts. This work provides protocols to take full advantages of components involved for enhanced solar-to-chemical energy conversion efficiency of hybrid artificial photosynthetic systems through rationally harnessing the charge transfer between them.

Recent Progress of Hollow Carbon Nanocages: General Design Fundamentals and Diversified Electrochemical Applications

Hollow carbon nanocages (HCNCs) consisting of sp2  carbon shells featured by a hollow interior cavity with defective microchannels (or customized mesopores) across the carbon shells, high specific surface area, and tunable electronic structure, are quilt different from the other nanocarbons such as carbon nanotubes and graphene. These structural and morphological characteristics make HCNCs a new platform for advanced electrochemical energy storage and conversion. This review focuses on the controllable preparation, structural regulation, and modification of HCNCs, as well as their electrochemical functions and applications as energy storage materials and electrocatalytic conversion materials. The metal single atoms-functionalized structures and electrochemical properties of HCNCs are summarized systematically and deeply. The research challenges and trends are also envisaged for deepening and extending the study and application of this hollow carbon material. The development of multifunctional carbon-based composite nanocages provides a new idea and method for improving the energy density, power density, and volume performance of electrochemical energy storage and conversion devices.

Z-scheme Cu2MoS4/CdS/In2S3 nanocages heterojunctions-based PEC aptasensor for ultrasensitive assay of fumonisin B1 via signal amplification with hollow PtPd–CoSnO3 nanozyme

Fumonisin B1 (FB1), the most prevalent and highest toxicity mycotoxins among fumonisins family, poses threats to human especially children and infants even at a trace level. Therefore, its facile and sensitive detection is of importance. Herein, Z-scheme Cu₂MoS₄/CdS/In₂S₃ nanocage-like heterojunctions (labeled Cu₂MoS₄/CdS/In₂S₃) were synthesized, whose photoelectrochemical (PEC) property and electron transfer mechanism were strictly investigated. The Cu₂MoS₄/CdS/In₂S₃ behaved as photoactive substrate for building a PEC sensing platform for detection of FB1, integrated with PtPd alloy modified hollow CoSnO₃ nanoboxes (labeled PtPd-CoSnO₃) nanozyme. By virtue of the stronger affinity between the target FB1 and its aptamer (FB1-Apt), the photocurrent was recovered by releasing the CoSnO₃-PtPd₃ modified FB1-Apt (FB1-Apt/PtPd-CoSnO₃) from the photoanode, which can terminate the catalytic precipitation reaction for its peroxidase-like property. The resultant PEC aptasensor exhibited a wider dynamic linear range from 1 × 10^-4 to 1 × 10² ng mL^-1 with a lower limit of detection (0.0723 pg mL^-1). Thus, this research provides a feasible PEC sensing platform for routine analysis of other mycotoxins in practice.

Carbon Quantum Dots Accelerating Surface Charge Transfer of 3D PbBiO2I Microspheres with Enhanced Broad Spectrum Photocatalytic Activity-Development and Mechanism Insight

The development of a highly efficient, visible-light responsive catalyst for environment purification has been a long-standing exploit, with obstacles to overcome, including inefficient capture of near-infrared photons, undesirable recombination of photo-generated carriers, and insufficient accessible reaction sites. Hence, novel carbon quantum dots (CQDs) modified PbBiO₂I photocatalyst were synthesized for the first time through an in-situ ionic liquid-induced method. The bridging function of 1-butyl-3-methylimidazolium iodide ([Bmim]I) guarantees the even dispersion of CQDs around PbBiO₂I surface, for synchronically overcoming the above drawbacks and markedly promoting the degradation efficiency of organic contaminants: (i) CQDs decoration harness solar photons in the near-infrared region; (ii) particular delocalized conjugated construction of CQDs strength via the utilization of photo-induced carriers; (iii) π-π interactions increase the contact between catalyst and organic molecules. Benefiting from these distinguished features, the optimized CQDs/PbBiO₂I nanocomposite displays significantly enhanced photocatalytic performance towards the elimination of rhodamine B and ciprofloxacin under visible/near-infrared light irradiation. The spin-trapping ESR analysis demonstrates that CQDs modification can boost the concentration of reactive oxygen species (O₂^•-). Combined with radicals trapping tests, valence-band spectra, and Mott-Schottky results, a possible photocatalytic mechanism is proposed. This work establishes a significant milestone in constructing CQDs-modified, bismuth-based catalysts for solar energy conversion applications.

Architecture and Kinetic Studies of Photocatalytic H2O2 Generation and H2 Evolution through Regulation of Spatial Charge Transfer via Z-Scheme Path over a (001) Facet Engineered TiO2@MXene/B-g-C3N4 Ternary Hybrid

Spatial charge separation and migration are the critical shortcomings dominating the core energy conversion corridors of photocatalytic systems. Here, a biomimetic multi-interfacial architecture providing strong coupled interaction and rapid charge transmission for photostable and competent photocatalytic H2O2 production and H2 evolution is proposed. The triple-hybrid all-solid-state Z-scheme system was formed with the (001) facet exposed TiO2 nanosheets derived from MXene layers and B-g-C3N4 nanosheets (M/(001)TiO2@BCN) through an electrostatic self-assembly strategy with intimate electronic interaction due to Ti orbital modulation and proper stacking among the hybrids. The metallic and highly conductive MXene layers act as solid state electron mediators in the Z-scheme heterojunction that promote electron-hole separation and migration efficiency. Specifically, the MTBCN-12.5 composite provides optimum yield of H2O2 up to 1480.1 μmol h-1 g-1 and a H2 evolution rate of 408.4 μmol h-1 (with ACE 6.7%), which are 4 and 20 fold greater than the pristine BCN, respectively. The enhanced photocatalytic performance is systematically identified by the increased surface area, higher cathodic and anodic current densities of -1.01 and 2.27 mA cm-2, delayed charge recombination as supported by PL and EIS measurement, and excellent photostability. The Z-scheme charge transfer mechanism is validated by time-resolved photoluminescence (TRPL) analysis, cyclic voltametric analysis, and the radical trapping experiment as detected by PL analysis. This research marks a substantial advancement and establishes the foundation for future design ideas in accelerating charge transfer.

Plasmonic Metal Mediated Charge Transfer in Stacked Core-Shell Semiconductor Heterojunction for Significantly Enhanced CO2 Photoreduction

Construction of core-shell semiconductor heterojunctions and plasmonic metal/semiconductor heterostructures represents two promising routes to improved light harvesting and promoted charge separation, but their photocatalytic activities are respectively limited by sluggish consumption of charge carriers confined in the cores, and contradictory migration directions of plasmon-induced hot electrons and semiconductor-generated electrons. Herein, a semiconductor/metal/semiconductor stacked core-shell design is demonstrated to overcome these limitations and significantly boost the photoactivity in CO₂  reduction. In this smart design, sandwiched Au serves as a "stone", which "kills two birds" by inducing localized surface plasmon resonance for hot electron generation and mediating unidirectional transmission of conduction band electrons and hot electrons from TiO₂  core to MoS₂  shell. Meanwhile, upward band bending of TiO₂  drives core-to-shell migration of holes through TiO₂ -MoS₂  interface. The co-existence of TiO₂  → Au → MoS₂  electron flow and TiO₂  → MoS₂  hole flow contributes to spatial charge separation on different locations of MoS₂  outer layer for overall redox reactions. Additionally, reduction potential of photoelectrons participating in the CO₂  reduction is elaborately adjusted by tuning the thickness of MoS₂  shell, and thus the product selectivity is delicately regulated. This work provides fresh hints for rationally controlling the charge transfer pathways toward high-efficiency CO₂  photoreduction.

Adducing Knowledge Capabilities of Instrumental Techniques Through the Exploration of Heterostructures' Modification Methods

The ongoing evolution of technology has facilitated the global research community to rapidly escalate the constant development of novel advancements in science. At the forefront of such achievements in the field of photocatalysis is the utilisation, and in oftentimes, the adaptation of modern instrumentation to understand photo-physical properties of complex heterostructures. For example, coupling in-situ X-ray Raman scattering spectroscopy for real-time degradation of catalytic materials.

Surface Structure Engineering of PdAg Alloys with Boosted CO2 Electrochemical Reduction Performance

Converting carbon dioxide into high-value-added formic acid as a basic raw material for the chemical industry via an electrochemical process under ambient conditions not only alleviates greenhouse gas effects but also contributes to effective carbon cycles. Unfortunately, the most commonly used Pd-based catalysts can be easily poisoned by the in situ formed minor byproduct CO during the carbon dioxide reduction reaction (CRR) process. Herein, we report a facile method to synthesize highly uniformed PdAg alloys with tunable morphologies and electrocatalytic performance via a simple liquid synthesis approach. By tuning the molar ratio of the Ag⁺ and Pd²⁺ precursors, the morphologies, composition, and electrocatalytic activities of the obtained materials were well-regulated, which was characterized by TEM, XPS, XRD, as well as electrocatalytic measurements. The CRR results showed that the as-obtained Pd₃Ag exhibited the highest performance among the five samples, with a faradic efficient (FE) of 96% for formic acid at -0.2 V (vs. reference hydrogen electrode (RHE)) and superior stability without current density decrease. The enhanced ability to adsorb and activate CO₂ molecules, higher resistance to CO, and a faster electronic transfer speed resulting from the alloyed PdAg nanostructure worked together to make great contributions to the improvement of the CRR performance. These findings may provide a new feasible route toward the rational design and synthesis of alloy catalysts with high stability and selectivity for clean energy storage and conversion in the future.

Rational fabrication of cadmium-sulfide/graphitic-carbon-nitride/hematite photocatalyst with type II and Z-scheme tandem heterojunctions to promote photocatalytic carbon dioxide reduction

Artificial photosynthesis has become one of the most attractive strategies for lowering atmospheric carbon dioxide (CO₂) level and achieving the carbon balance; whereas, the fast electron-hole recombination and sluggish charge transfer in photocatalysts are themain stumbling blocks to the applications. Constructing semiconductor nano-heterostructures provides a promising strategy to accelerate the separation and transfer of photoinduced charge carriers for promoting the multielectron CO₂ reduction reaction. Herein, a CdS/g-C₃N₄/α-Fe₂O₃ three-component photocatalyst consisting of type II and Z-scheme tandem heterojunctions is skillfully fabricated via the solvothermal synthesis followed with photoinduced deposition. The CdS/g-C₃N₄/α-Fe₂O₃ tandem-heterojunction photocatalyst exhibits superior performance toward the conversion of CO₂ to fuels (CO and CH₄), compared with the single- and binary-component systems, owing to the favorable energy-level alignment, accelerated charge separation, facilitated water dissociation and sufficient reactive-hydrogen provision. The total consumed electron number of CdS/g-C₃N₄/α-Fe₂O₃ catalyst for CO₂ reduction is about 10.5 times that of pure g-C₃N₄. The photocatalytic mechanism is elucidated according to detailed characterizations and in-situ spectroscopy analyses. This work sheds light on the rational construction of heterojunction photocatalysts to promote the conversion of CO₂ to solar fuels, without using any sacrifice reagent or noble-metal cocatalysts.

Co-Doped Mn3 O4 Nanocubes via Galvanic Replacement Reactions for Photocatalytic Reduction of CO2 with High Turnover Number

The synthesis of Co-doped Mn₃ O₄ nanocubes was achieved via galvanic replacement reactions for photo-reduction of CO₂ . Co@Mn₃ O₄ nanocubes could efficiently photo-reduce CO₂ to CO with a remarkable turnover number of 581.8 using [Ru(bpy)₃ ]Cl₂  ⋅ 6H₂ O as photosensitizer and triethanolamine as sacrificial agent in acetonitrile and water. The galvanic replaced Co species are homogeneously distributed at the outer surface of Mn₃ O₄ , providing catalytic active sites during CO₂ reduction reactions, which facilitate the separation and migration of photogenerated charge carriers, further benefiting the outstanding photocatalytic performance of CO₂ reduction. Density functional theory calculations revealed that the decreasing of conduction band maximum in Co@Mn₃ O₄ was beneficial to the electron attachment from the excited sensitized molecule, which promoted photocatalytic reduction of CO₂ .

Ni-Co Bimetallic Hydroxide Nanosheet Arrays Anchored on Graphene for Adsorption-Induced Enhanced Photocatalytic CO2 Reduction

Photocatalytic CO₂ reduction can be implemented to use CO₂ , a greenhouse gas, as a resource in an energy-saving and environmentally friendly way, in which suitable catalytic materials are required to achieve high-efficiency catalysis. Insufficient accessible active sites on the catalyst surface and inhibited electron transfer severely limit the photocatalytic performance. Therefore, porous aerogels are constructed from composites comprising different ratios of Ni-Co bimetallic hydroxide (Ni_x Co_y ) grown on reduced graphene oxide (GR) into a hierarchical nanosheet-array structure using a facile in situ growth method. Detailed characterization shows that this structure exposes numerous active sites for enhanced adsorption-induced photocatalytic CO₂ reduction. Moreover, under the synergistic effect of Ni-Co bimetallic hydroxide, the CO₂ adsorption capacity as well as charge-carrier separation and transfer are excellent. As a result, the Ni₇ Co₃ -GR catalyst exhibits highly improved catalytic performance when compared with recently reported values, with a high CO release rate of 941.5 µmol h^-1  g^-1 and a selectivity of 96.3% during the photocatalytic reduction of CO₂ . This work demonstrates a new strategy for designing nanocomposites with abundant active sites structures.

Self-Assembled Zeolitic Imidazolate Framework/CdS Hollow Microspheres with Efficient Charge Separation for Enhanced Photocatalytic Hydrogen Evolution

Enhanced interfacial charge separation is of great importance to high-efficiency photocatalytic hydrogen production. Herein, we successfully fabricated novel ZIF-67/CdS hollow sphere (HS) and ZIF-8/CdS HS heterostructures through an in situ self-assembly process, in which ZIF-67 and ZIF-8 are closely coated on CdS HSs to form "double-shell"-like structures. This hierarchical heterostructure with porous outer layers on the surface of CdS HSs can expose accessible active sites and possess close contact. Upon visible-light illumination, the optimal proportion of ZIF-67/CdS HS displays a hydrogen generation rate of 1721 μmol g^-1 h^-1, which is 11.9 and 3.1 times higher than that of a pure CdS HS (145 μmol g^-1 h^-1) and ZIF-8/CdS HS (555 μmol g^-1 h^-1), respectively. The proposed photocatalytic mechanism is explored: ZIF-8/CdS HS follows the type-II mechanism, and ZIF-67/CdS HS follows the Z-scheme mechanism. The reason for the higher photocatalytic activity of ZIF-67/CdS HS is that ZIF-67 not merely with a porous structure facilitates the diffusion of H₂ gas, but with a well-matched band structure promotes charge transfer and separation.