Charge Transfer Channel Research Articles

Construction of an Axial Charge Transfer Channel Between Single-Atom Fe Sites and Nitrogen-Doped Carbon Supports for Boosting Oxygen Reduction.

The introduction of axial-coordinated heteroatoms in Fe─N─C single-atom catalysts enables the significant enhancement of their oxygen reduction reaction (ORR) performance. However, the interaction relationship between the axial-coordinated heteroatoms and their carbon supports is still unclear. In this work, a gas phase surface treatment method is proposed to prepare a series of X─Fe─N─C (X = O, P, and S) single-atom catalysts with axial X-coordination on graphitic-N-rich carbon supports. Synchrotron-based X-ray absorption near-edge structure spectra and X-ray photoelectron spectroscopy indicate the formation of an axial charge transfer channel between the graphitic-N-rich carbon supports and single-atom Fe sites by axial O atoms in O─Fe─N─C. As a result, the O─Fe─N─C exhibits excellent ORR performance with a half-wave potential of 0.905V versus RHE and a high specific capacity of 884 mAh g-1 for zinc-air battery, which is superior to other X─Fe─N─C catalysts without axial charge transfer and the commercial Pt/C catalyst. This work not only demonstrates a general synthesis strategy for the preparation of single-atom catalysts with axial-coordinated heteroatoms, but also presents insights into the interaction between single-atom active sites and doped carbon supports.

Carbon nanotube reinforced FeMoO4 nanorods as a high-performance anode for sodium-ion batteries

Iron molybdate (FeMoO4) nanostructures show great promise as a superior anode for sodium-ion batteries. However, its use in practical application is hampered by its poor electronic conductivity, large volume changes and sluggish reaction kinetics. Herein, we have developed an interconnected network of multiwall carbon nanotube (CNT) and FeMoO4 (FMO) by a simple one-step hydrothermal method. As well as providing efficient channels for charge transfer and diffusion, highly conductive CNTs also have a degree of volume elasticity and excellent electrical conductivity to ensure migration of sodium ions, enabling both fast kinetics and long-term stability. As a result, the FMO@CNT anode delivers a high reversible capacity of 485 mA h g−1 at 0.05 A/g and very long cycling stability with a capacity of 75 mA h g−1 after 1000 cycles at 1 A/g. Furthermore, by combining the ex-situ X-ray diffraction, ex situ X-ray photoelectron spectroscopy and cyclic voltammetry results, sodium ion storage mechanism of the FMO@CNT electrode obeys a conversion mechanism. The results of this work provide a better understanding on the sodium ion storage mechanism of binary metal oxides.

Ultrathin BiOCl-OV/CoAl-LDH S-scheme heterojunction for efficient photocatalytic peroxymonosulfate activation to boost Co (IV)=O generation

Sustainable and rapid production of high-valent cobalt-oxo (Co(IV)=O) species for efficiently removing organic pollutants is challenging in permoxymonosulfate (PMS) based advanced-oxidation-processes (AOPs) due to the limitation of the high 3d-orbital electronic occupancy of Co and slow conversion from Co(III) to Co(II). Herein, S-scheme BiOCl-OV/CoAl-LDH heterojunction were constructed by ultrathin BiOCl with the oxygen-vacancy (OV) self-assembled with ultrathin CoAl-LDH. OV promoted the formation of charge transfer channel (Bi-O-Co bonds) at the interface of the heterojunction and reduced electron occupation of the Co 3d-orbital to facilitate the generation of Co(IV)=O in the BiOCl-OV/CoAl-LDH/PMS/Visible-light system. S-scheme heterojunction accelerated the photogenerated electrons to allow rapid conversion of Co(III) to Co(II), promoting the fast two-electron transfer from Co(II) to Co(IV)=O. Consequently, the developed BiOCl-OV/CoAl-LDH/PMS/Visible-light system showed excellent degradation efficiency for most of organic pollutions, and exhibited very high removal capability for the actual industrial wastewater. This study provides a new insight into the evolution of Co(IV)=O and the coordinative mechanism for photocatalysis and PMS activation.

Chemomechanics Engineering Promotes the Catalytic Activity of Spinel Oxides for Sulfur Redox Reaction

AbstractCooperative catalysis is a promising approach to enhance the sluggish redox kinetics of lithium polysulfides (LiPSs) for practical lithium–sulfur (Li–S) batteries. However, the elusory synergistic effect among multiple active sites makes it challenging to accurately customize the electronic structure of catalysts. Herein, a strategy of precisely tailoring eg orbitals of spinel oxides through chemomechanics engineering is porposed to regulate LiPSs retention and catalysis. By manipulating the regulable cations in MnxCo3‐xO4, it is theoretically and experimentally revealed that the lattice strain induced by the Jahn–Teller active and high‐spin Mn3+ at octahedral (Oh) sites can increase the eg occupancy of low‐spin Co3+Oh, which effectively regulates the chemical affinity toward LiPSs and establishes an unblocked channel for intrinsic charge transfer. This leads to a volcano‐type correlation between the eg occupancy at Oh sites and sulfur redox activity. Benefitting from the cooperative catalysis of dual‐active sites, MnCo2O4 with an average eg occupancy of 0.45 affords the most appropriate adsorption strength and rapid redox kinetics toward LiPSs, leading to remarkable rate performance and capacity retention for the assembled Li–S batteries. This work demonstrates the promise of chemomechanics engineering for optimizing the eg occupancy to achieve efficient sulfur redox catalysts.

Insights into pseudocapacitive mechanism of aqueous ammonium-ion supercapacitors with exceptional energy density and cyclability

Aqueous ammonium-ion (NH4+) supercapacitors (AASCs) have recently garnered increased concerns but are consistently facing the challenge of lower energy density. Herein, a high-performance electrode (CuCo2S4@CP) with pseudocapacitive property has been synthesized and primordially applied to AASCs. The CuCo2S4@CP electrode has an ultrahigh specific capacity of 1512 C g−1 at 1 A g−1 and a distinguished cyclic stability of 87.74 % after 10,000 cycles. When the CuCo2S4@CP electrode is combined with the activated carbon (AC) negative electrode, the CuCo2S4@CP//AC device exhibits a high specific capacity of 547 C g−1 at 1 A g−1, excellent cycle stability (83.28 % at 10 A g−1), high energy density of 74.17 Wh kg−1, and excellent device consistency. In addition, the charge transfer mechanism of CuCo2S4@CP electrode in NH4+electrolyte has been elucidated. The CuCo2S4 surface density functional theory (DFT) elucidates that NH4+ has a minimal contribution to the surface, implying an insertion behavior of NH4+ within the CuCo2S4 lattice. Subsequent ex-situ characterization further confirms the energy storage process, revealing charge transfer to Co atoms following NH4+ insertion into CuCo2S4. The analysis of charge distribution illustrates an energy storage mechanism wherein the hydrogen bond formed between NH4+ and CuCo2S4 serves as the transport channel for charge transfer, facilitating the process of electrons from NH4+ to Co atoms. Therefore, the pseudocapacitive mechanism of CuCo2S4 with NH4+ provides a blueprint for sustainable energy storage with high energy density in aqueous electrolyte.

Mn-S chemical bond mediated Z-scheme photocatalyst boosting efficient H2 evolution with apparent quantum yield exceeding 32% under visible light

Developing a highly effective solar-to-H2 conversion system is a promising strategy for carbon neutrality. Here, we report a chemically bonded Z-scheme photocatalyst by specifically linking the conduction band site of ZnIn2S4 with the valence band site of Mn0.3Cd0.7S1-x. Deviates from the typical van der Waals interactions between two semiconductors, the in-built robust binding force (Mn-S bond) and charge transfer channel facilitates the electron mobility, minimizes detrimental deep charge trapping, and prolongs the active charge lifetime from 983 ps to 4250 ps. The sulfur vacancies in Mn0.3Cd0.7S1-x are partially refilled by atoms of the same element in ZnIn2S4 during the in-situ formation of heterojunctions, which promotes and solidates the establishment of interfacial chemical bonds. The optimal photocatalyst achieves a high quantum efficiency of 32.71 % at 420 nm. This study offers a new insight into the development of Z-Scheme heterojunctions via a synergistic approach involving doping, vacancy filling and strong interfacial chemical bonds.

Amorphous nitrogen-doped carbon layers forming the interfacial channel for rapid charge transfer in ZnIn2S4/BiVO4 Z-scheme photocatalyst for enhancing organic pollutants degradation with simultaneous hydrogen evolution

Efficient photocatalytic hydrogen evolution from the organic wastewater represents an ideal solution for simultaneously addressing energy shortages and environmental pollution. However, the sluggish transport of photogenerated carriers at contact interface poses a key obstacle to enhancing photocatalytic activity. Here, ZnIn2S4/BiVO4@N-C (ZIS/BVO@N-C) Z-scheme photocatalysts were successfully constructed by a simple hydrothermal-impregnation method. ZIS/BVO@N-C-10% demonstrated outstanding photocatalytic performance, achieving a hydrogen evolution rate of 2695.68 μmol·g−1·h−1 and a degradation rate of 492.96 mmol·g−1·h−1 under visible light, surpassing those of ZIS (851.52 μmol·g−1·h−1 and 174.83 mmol·g−1·h−1) and ZIS/BVO-10% (1228.98 μmol·g−1·h−1 and 277.78 mmol·g−1·h−1). Characterization results and density functional theory (DFT) calculations revealed that the introduction of the N-C layer reduced interfacial impedance and enhanced the strength of interfacial electric field, overcoming the interfacial barrier and improving the photogenerated separation and migration efficiency at the interface, and ultimately enhancing the photocatalytic activity of ZIS/BVO@N-C. Based on experimental and characterization results, the photocatalytic mechanism of ZIS/BVO@N-C Z-scheme has been proposed. Furthermore, ZIS/BVO@N-C exhibited excellent stability, highlighting its potential for practical applications. This work also presents a new strategy for designing highly active Z-scheme photocatalysts for organic wastewater treatment and simultaneous hydrogen energy recovery.

Sp2-c linked Cu-based metal-covalent organic framework for chemical and photocatalysis synergistic reduction of uranium

The reduction of hexavalent uranium to tetravalent uranium is an effective strategy for controlling uranium contamination in wastewater. Herein, a CC bonded metal-covalent organic framework (Cu-TMT) was synthesized via the Aldol condensation reaction by using the metal cluster Cu3(PyCA)3 and 2,4,6-trimethyl-1,3,5-triazine (TMT) for the chemical and photocatalytic synergistic reduction of uranium. In the Cu-TMT, the low-valent Cu in the metal clusters provides the framework with numerous distributed redox sites being capable of chemically reducing UVI. Meanwhile, the encapsulating Cu clusters in long-range ordered frameworks can provide fast transport channels for intramolecular charge transfer and effectively inhibit electron/hole complexation, making Cu-TMT suitable for photocatalytic reduction of uranium. The chemical reduction of uranium by Cu-TMT was verified under light-avoidance conditions, reaching 659.5 mg g−1. After exposure of Cu-TMT to light, the amount of reduced uranium further increases to 1438.8 mg g−1 with 98.1 % removal rate of actual uranium containing wastewater. This study not only expands the range of applications of variable valence metal covalent organic frameworks, but also provides unique insights into the effective combination of chemical and photocatalytic reduction strategies for removing UVI in a single material.

Construction of La2O3/AgCl S-scheme heterojunction with interfacial chemical bond for efficient photocatalytic degradation of bisphenol A

The formation of interfacial chemical bonds in S-scheme heterostructure is a crucial factor to realize efficient interfacial charge transfer. High-energy mechanical ball-milling is an effective method to form interfacial chemical bonds. In this work, an S-scheme La2O3/AgCl heterojunction catalyst was designed and prepared by ball-milling method. XPS, FTIR and Raman measurements showed that La-Cl chemical bond was formed at the interface of La2O3 and AgCl and an S-scheme charge transfer path mechanism existed in the La2O3/AgCl composite. The results of electrochemistry, photo-electrochemistry, capture experiments, free radical measurement and EPR verified that the S-scheme heterojunction and the interfacial La-Cl bond significantly accelerated the charge transfer rate between La2O3 and AgCl, and enhanced the photocatalytic capability of the composite catalysts. The degradation rate of bisphenol A by La2O3/AgCl heterojunction composite (LA50) reached 99 % in 20 min, and it also had excellent anti-interference ability and cycling stability. The toxicity of the degradation intermediates of bisphenol A was much less than itself, as calculated by TEST simulation. This work provided a promising strategy for improving the performance of S-scheme heterojunction catalysts by introducing interfacial chemical bonds as charge transfer channels.

Steering charge flow in hierarchical ZnIn2S4/TiO2/Ti3C2 heterojunction for noble-metal-free photocatalytic hydrogen production

The construction of effective photogenerated charge transfer channels through interface engineering is the key to achieving the highly efficient of photocatalysts. Herein, sandwich-like ZnIn2S4/TiO2/Ti3C2 nanosheets integrated type-II heterostructure with Schottky junction are reasonably fabricated by low temperature in-situ growth method. Benefitting from the intensive visible light absorption of ZnIn2S4, the fast electron transport of TiO2, the rich active sites in Ti3C2, as well as the intimate interface coupling and the matched band alignment among ternary components, enhanced hydrogen production can be achieved with ZnIn2S4/TiO2/Ti3C2 hierarchical photocatalyst under visible light irradiation in the absence of noble metal co-catalysts. The concept of coupling type-II heterostructure with the Schottky barrier can steer the charge flow and boost the charge carrier separation and transfer across the interfacial domain, which may spark new ensemble design for efficient solar energy harvesting and conversion.

Constructing Interfacial Charge Transfer Channels and Electric Field in Violet Phosphorus-Based van der Waals Heterojunction for Phototherapy of Periodontitis.

Periodontitis, a chronic oral disease instigated by bacteria, severely compromises human oral health. The prevailing clinical treatment for periodontitis involves mechanical scraping in conjunction with antibiotics. Phototherapy is employed to rapidly remove the bacteria and achieve periodontitis treatment, effectively circumventing the adverse effects associated with traditional therapies. Constructing 2D/2D van der Waals (VDW) heterojunctions is a key strategy for obtaining excellent photocatalytic activity. Herein, a 2D/2D violet phosphorus (VP)/Ti3C2 VDW heterojunction is designed using an interfacial engineering strategy. By constructing an electron transport "bridge" (P-Ti bond) at the heterogeneous interface as an effective transfer channel for photogenerated carriers, a compact monolithic structure between the VP and Ti3C2 phases is formed, and the spatial barrier for electron transfer at the interface is eliminated. Meanwhile, the strong directional built-in electric field induced by the intensive electron-coupling effect at the heterogeneous interface served as an internal driving force, which greatly accelerates the exciton dissociation and charge transfer in the photocatalytic process. These excited photogenerated electrons and holes are trapped by O2 and H2O on the surfaces of Ti3C2 and VP, respectively, and are subsequently catalytically converted to antibacterial reactive oxygen species (ROS). The VP/Ti3C2 VDW heterojunction eradicated 97.5% and 98.48% of Staphylococcus aureus and Escherichia coli, respectively, by photocatalytic and photothermal effects under visible light for 10 min. The VP/Ti3C2 nanoperiodontal dressing ointment effectively attenuated inflammatory response, reduced alveolar bone resorption, and promoted periodontal soft and hard tissue repair. Its periodontitis therapeutic effect outperforms the clinically used Periocline.

In-situ anion-exchange construction of Z-scheme Ag3PO4/AgI, derived AgCl/Ag3PO4/AgI and Ag2CO3/Ag3PO4/AgI composites with multiple redox energy bands and charge transfer pathways for efficient absorption and sonocatalytic properties

Z-scheme Ag3PO4/AgI composites were synthesized by facile in-situ anion-exchange method at room temperature (RT). All the catalysts have excellent affinity to dyes and adsorb larger than 70 % of Methyl blue. The fastest adsorption equilibrium of Ag3PO4 (qe: 25.9278 mg/g) with low specific surface area (SSA: 4.6624 m2/g) can be rapidly attained for 6 min. The best color removal efficiency (RE) for Methyl blue over all the composites can rapidly increase to 100 % within 45 min. Meanwhile, the highest RE for RhB over S3 is 98.9 % for 60 min, and corresponding rate constant (k) is 0.07018 min−1. After adding NaCl or Na2CO3 into sonocatalysis, because of the formation of novel ternary AgCl/Ag3PO4/AgI and Ag2CO3/Ag3PO4/AgI during sonocatalytic process, the best REs for RhB over S3 composite increase from 89.8 % (no scavenger) to 98.2 % (1.2 mM NaCl), or to 97.6 % (1.8 mM Na2CO3) for 30 min, respectively, and the REs for Methyl blue over S3 are about 100 % for 10 min. From single Ag3PO4 to binary Ag3PO4/AgI, and to ternary Ag2CO3/Ag3PO4/AgI or AgCl/Ag3PO4/AgI, REs are significantly enhanced. New redox energy bands and charge transfer channels lead to efficiently spatial charge separation and further activation of hole (h+), superoxide anions (·O2−), hydroxyl radicals (·OH). Additionally, the relation among oxygen vacancies (Ov), Zeta potential and RE was discussed in detail. Density functional theory (DFT) calculations were used to make clear charge transfer and sonocatalytic mechanism. The evaluation of used samples, adsorption kinetics and modes, diverse degradation pathways and sonocatalytic mechanisms were also discussed in detail. The work provides a novel in-situ strategy for real-time control of catalytic performance by rapidly forming new phase during catalysis at RT. Furthermore, the strategy obviously facilitates real-time development of rare more than ternary composites for enhanced catalytic performance.

Soft Actuator with Biomass Porous Electrode: A Strategy for Lowering Voltage and Enhancing Durability.

Electroactive artificial muscles with deformability have attracted widespread interest in the field of soft robotics. However, the design of artificial muscles with low-driven voltage and operational durability remains challenging. Herein, novel biomass porous carbon (BPC) electrodes are proposed. The nanoporous BPC enables the electrode to provide exposed active surfaces for charge transfer and unimpeded channels for ion migration, thus decreasing the driving voltage, enhancing time durability, and maintaining the actuation performances simultaneously. The proposed actuator exhibits a high displacement of 13.6 mm (bending strain of 0.54%) under 0.5 V and long-term durability of 99.3% retention after 550,000 cycles (∼13 days) without breaks. Further, the actuators are integrated to perform soft touch on a smartphone and demonstrated as bioinspired robots, including a bionic butterfly and a crawling robot (moving speed = 0.08 BL s-1). This strategy provides new insight into the design and fabrication of high-performance electroactive soft actuators with great application potential.

Construction of charge transfer channels inside h-BN/ g-C3N4 composites to enhance photocatalytic activity

Water resources are an indispensable part of life, but the current water pollution problem is facing serious challenges. In this article, two-dimensional g-C3N4 and h-BN used as raw materials, a series of h-BN/g-C3N4 (BCN) composite catalysts with varying mass by designed and synthesized using combination of simple solvent volatilization and high-temperature thermal polymerization method. The degradation rate of the BCN-2 catalyst was impressively 13.7 times higher than that of the bulk g-C3N4 when RhB was used as the target pollutants, demonstrating significantly enhanced photocatalytic performance compared to both bulk g-C3N4 and h-BN. The burst experiments on free radicals revealed that h+ and ∙O2− played a predominant role in the photocatalytic system. Moreover, the introduction of h-BN into g-C3N4 nanosheets modulated their microstructure, facilitating effectively hole migration channels and enhancing synergistically the separation efficiency of photogenerated electron-hole pairs. Consequently, the composites of h-BN/g-C3N4 with remarkably enhanced photocatalytic activity were obtained.

Visible-Light-Driven Z-Type Pg-C3N4/Nitrogen Doped Biochar/BiVO4 Photo-Catalysts for the Degradation of Norfloxacin.

Antibiotics cannot be effectively removed by traditional wastewater treatment processes, and have become widespread pollutants in various environments. In this study, a Z-type heterojunction photo-catalyst Pg-C3N4 (PCN)/Nitrogen doped biochar (N-Biochar)/BiVO4 (NCBN) for the degradation of norfloxacin (NOR) was prepared by the hydrothermal method. The specific surface area of the NCBN (42.88 m2/g) was further improved compared to BiVO4 (4.528 m2/g). The photo-catalytic performance of the catalyst was investigated, and the N-Biochar acted as a charge transfer channel to promote carrier separation and form Z-type heterojunctions. Moreover, the NCBN exhibited excellent performance (92.5%) in removing NOR, which maintained 70% degradation after four cycles. The main active substance of the NCBN was •O2-, and the possible degradation pathways are provided. This work will provide a theoretical basis for the construction of heterojunction photo-catalysts.

Enhanced photocatalytic performance of MXene-Modified cation-exchanged CoFe-LDH/CoFeCrO4 heterostructure for Antibiotic degradation and hydrogen production through synergistic charge dynamics

Systemizing an effective charge-transfer channel across a junction interface replete with ample active sites for enhancing the photocatalytic activity of semiconducting materials presents a formidable challenge. Here, we present a novel approach based on an in situ hydrothermal method for synthesizing CoFe-Layered Double Hydroxide (LDH)/CoFeCrO4 heterojunction materials that were partially derived from CoFe-LDH. These materials synergistically interact with Ti3C2 MXene nanosheets facilitating multi-interface interactions. Indeed, the highest tetracycline hydrochloride degradation rate of nearly 92% in 2 h was achieved because of the intense synergy between the CoFe-LDH/CoFeCrO4 heterojunction material optimized with 7.5 wt% of MXene nanosheets (CMC-7.5). This degradation performance was 3.1 times greater than that of the original CoFe-LDH. Further, CMC-7.5 produces the highest H2 gas of 458.79 μmol h−1g−1 from a photocatalytic water splitting reaction. The formation of a Schottky energy barrier between the partially derived CoFe-LDH/CoFeCrO4 unit and MXene promoted the fast transfer of photogenerated electrons from CoFe-LDH/CoFeCrO4 to the surface of MXene, thereby providing a plethora of active sites for photocatalytic reactions. Photoelectrochemical assessments using transient and linear sweep voltammetry along with electrochemical impedance spectroscopy confirmed efficient charge carrier transfer. Moreover, the optimized CMC-7.5 photoelectrode has a superior integral area and exhibited excellent stability over 100 cycles. Finally, the study outlines the construction of several advanced materials with multi-interface heterojunctions involving cation-exchanged LDH derivatives with high photogenerated charge carrier separation efficiency and minimal interfacial migration resistance to serve as stability benchmarks for practical applications.

Enhanced charge transport in 2D inorganic molecular crystals constructed with charge‐delocalized molecules

AbstractOutstanding charge transport in molecular crystals is of great importance in modern electronics and optoelectronics. The widely adopted strategies to enhance charge transport, such as restraining intermolecular vibration, are mostly limited to organic molecules, which are nearly inoperative in 2D inorganic molecular crystals currently. In this contribution, charge transport in 2D inorganic molecular crystals is improved by integrating charge‐delocalized Se8 rings as building blocks, where the delocalized electrons on Se8 rings lift the intermolecular orbitals overlap, offering efficient charge transfer channels. Besides, α‐Se flakes composed of charge‐delocalized Se8 rings possess small exciton binding energy. Benefitting from these, α‐Se flake exhibits excellent photodetection performance with an ultrafast response rate (~5 μs) and a high detectivity of 1.08 × 1011 Jones. These findings contribute to a deeper understanding of the charge transport of 2D inorganic molecular crystals composed of electron‐delocalized inorganic molecules and pave the way for their potential application in optoelectronics.

Coupling Reliable Interfacial Carrier Migration Channels with Visible-Light Response Antennas in ZnO-Based Heterostructure for Ameliorated Photocatalytic Hydrogen Generation.

Engineering targeted and reliable charge transfer pathways in multiphase photocatalysts remains a challenge. Herein, we conceptualize the Cd@CdS-ZnO/reduced graphene oxide (rGO)/ZnS heterostructures coupled with reliable carrier migration channels and visible-light response antennas by building rGO-integrated electrochemical nanoreactors and an ion-exchange process. In this ternary catalyst, the Cd clusters and rGO perform as charge relays to boost carrier transport via the Z-scheme route and accelerate photogenerated carriers to react with surface-adsorbed substances. Meanwhile, thanks to CdS, the heterostructures have photocatalytic properties under visible light illumination and can also inhibit self-corrosion by shielding Cd clusters to avoid disrupting charge transfer channels. Therefore, the special heterostructure demonstrates fascinating photocatalytic hydrogen production activity without the intervention of cocatalysts. This work provides a feasible protocol for improving the interfaces between metals and semiconductors to achieve efficient photocatalytic hydrogen generation.

Robust Er2O3/UiO-66-NH2 core–shell nanohybrid for efficient CO2 photoreduction via fast interfacial charge-transfer

Interfacial charge transfer in nanocomposites is one of the leading factors to CO2 photoreduction activity and selectivity; however, the modulation of interfacial contact still remains a compelling challenge. Here we present an in-situ assembly strategy to synthesize core–shell structured Er-UiO-66-NH2 heterojunction photocatalysts, achieving a stable CO evolution rate of 106.2 μmol·g−1·h−1 and a selectivity over 92 %. Our findings demonstrate that the coupled intermediate layer formed by solvothermal transformation creates a charge-transfer channel between Er2O3 and UiO-66-NH2, contributing to the effective spatial separation of photogenerated carriers. The well-defined gradient of band structures and interfacial built-in electric field at p-n heterojunctions direct photoelectrons migration, and facilitates the fast access to active Zr-oxo sites for efficient CO2 reduction. In-situ DRIFTS unravels that the superior catalytic activities can be attributed to the strong adsorption and activation capabilities for CO2 conversion to COOH* and CO* species. This work highlights an interfacial assembling strategy to design heterojunction photocatalysts for efficient solar fuel production.

Internal electric field promoted NCDs/BiOBr/AgBr Z-scheme heterojunction with rich oxygen vacancies for efficient photocatalytic degradation of tetracycline and reduction of Cr (VI)

It is important to prepare efficient photocatalysts for the degradation of antibiotics and heavy metals. In this study, NCDs/BiOBr/AgBr Z-scheme heterojunction photocatalysts with excellent performance were constructed. NCDs/BiOBr/AgBr form a Z-type heterojunction system with pyrrole nitrogen-doped carbon quantum dots (NCDs) as charge transfer channels. The internal electric field formed in NCDs/BiOBr/AgBr greatly facilitated electron transfer. The more easily broken Bi-O bonds were utilized in the synthesis to introduce rich oxygen vacancies (OVs) into NCDs/BiOBr/AgBr to promote molecular oxygen activation. Meanwhile, silver nanorods were reduced in the synthesis to enhance the photodegradation performance. The photocatalytic degradation of tetracycline (TC) and reduction of Cr (VI) were enhanced by about 4 and 6 times. The factors affecting the removal effects of TC and Cr (VI) were analyzed. The catalysts were also tested to have good stability and potential for application in real wastewater. The reactive oxygen species (ROS), which play a dominant role in the photodegradation of TC and Cr (VI) by NCDs/BiOBr/AgBr, were tested, and a possible photocatalytic mechanism was proposed.