Charge Transfer Channel Research Articles

Strongly Coupled Interface in Electrostatic Self-Assembly Covalent Triazine Framework/Bi19S27Br3 for High-Efficiency CO2 Photoreduction.

Constructing a strong bonded interface is highly desired to build fast charge-transfer channels and tune reactive sites for optimizing CO2 photoreduction. In this work, a covalent triazine framework (CTF) combined with a Bi19S27Br3 heterojunction is designed using an electrostatic self-assembly process. Due to the oppositely charged states between two components and ultrasonic treatment, a strong coupled interface is realized with the formation of Bi-C/N/O bonds, leading to robust interfacial polarization. This feature causes interfacial charge redistribution, intensifies the interaction between triazine N reactive sites and CO2, stabilizes the intermediate state, and lowers the reaction energy barrier. Meanwhile, the chemically bonded interface favors rapid electron migration from Bi19S27Br3 to CTF, as proved by ultrafast transient absorption spectroscopy and in situ irradiation XPS. As a result, CTF/Bi19S27Br3 delivers a superior CO2 photoreduction performance to yield CO (572.2 μmol g-1 h-1) in a pure water system, which is 38.6 times that of Bi19S27Br3, with apparent quantum yields up to 7.9 and 6.2% at 380 and 400 nm, respectively. This strong interfacial coupling strategy provides an accessible pathway to designing interfacial polarized, high-efficiency photocatalysts.

Boosting photoelectrochemical water splitting: enhanced hole transport in BiVO4 photoanodes via interfacial coupling

Co3O4, functioning as an efficient charge transfer channel while simultaneously modulating the electronic structure of the NiFe-LDH metal center. Together, they synergistically optimise the interfacial properties of the BiVO4 matrix composites.

Constructing fast charge transfer channels by multi-active sites on Bi2MoO6 photocatalyst enhance NO deep purification and inhibit NO2 generation

Constructing fast charge transfer channels by multi-active sites on Bi2MoO6 photocatalyst enhance NO deep purification and inhibit NO2 generation

Structure Engineering on Prussian Blue Analog Anode Toward Rapid Na‐Ion Storage

AbstractDeveloping high‐rate electrode materials is a critical enabler of fast‐charging Na‐ion battery (NIB). Prussian blue analog (PBA) with rapid charge transfer channels has shown significant potential as high‐rate NIB cathodes; however, the fast‐charging capability of reported PBA‐based anodes remains limited. This challenge primarily stems from the complete transformation of their original PBA‐based crystal structures during synthesis processes, resulting in loss of the inherent rapid charge transfer channels. Herein, a Ni‐Fe based PBA (Ni3[Fe(CN)6]2) with a representative PBA‐based crystal structure is presented as a prototype to investigate its potential as a NIB anode, and structural modification strategies are implemented to unlock its rapid Na‐ion storage. First, conversion reaction mechanism is demonstrated in the Ni3[Fe(CN)6]2 during sodiation, with a theoretical specific capacity of 357.2 mAh g−1. However, its reversible capacities after long‐term cycling and at high rates are low. To address these issues, structural optimization strategies including S incorporation, configurational entropy modulation, and coordination environment regulation are utilized. Consequently, its fast‐charging (≈40 s per charge with 245.0 mAh g−1 input) and excellent cycling capabilities are realized. This study demonstrates the feasibility of PBA as high‐rate NIB anodes, and promotes the further investigation into structural optimization strategies aimed at developing other fast‐charging electrodes.

Ab Initio Study of Electron Capture in Collisions of Protons with CO2 Molecules.

Ab initio calculations of cross sections for electron capture by protons in collisions with CO2 are carried out at energies between 100 eV/u and 50 keV/u, employing a semiclassical method within the Franck-Condon framework. The scattering wave function is expanded in a set of ab initio electronic wave functions of the HCO2+ supermolecule. The calculation is performed on several trajectory orientations to obtain orientation-averaged total cross sections. A two-state model with an exponential interaction between the entrance and the lowest charge transfer channel is proposed to describe the main aspects of the charge transfer process and to estimate the precision of the molecular expansion. The symmetry of the HOMO πg of CO2 is relevant to choose the signs of the molecular functions and to set up the orientation average of the cross sections. Very good agreement is found with the experimental charge transfer cross sections.

Enhanced supercapacitor performance and hydrogen evolution reaction using Nb2CTx MXene-integrated HKUST-1 MOF

Abstract This work aims to investigate how HKUST-1 metal-organic framework (MOF) and Nb2CTx MXene operate in concert to improve the catalytic activity in the hydrogen evolution reaction (HER) and the effectiveness of supercapacitors. While HKUST-1 offers a very porous structure that is favorable for charge storage, Nb2CTx serves as both a conductive substrate and a catalytic site for HER. This combination leads to better charge transfer channels and increased electroactive sites, which ultimately results in higher HER efficiency (shown by a notably lower Tafel slope of 52.42 mV/dec). In configurations of two and three electrodes, a specific capacity of 2168 C/g at a current density of 1.0 A/g is demonstrated by HKUST-1/Nb2CTx Moreover, the theHKUST-1/Nb2CTx combination, in particular the HKUST-1/Nb2CTx//AC composite, shows remarkable stability; after 1000 cycles, they still retain 95 % of their capacity and achieve 97% coulombic efficiency. The HKUST-1/Nb2CTx decorated electrode exhibited energy and power density, reaching approximately 89 Wh/kg and 938 W/kg in two-electrode (real device) configurations. These results highlight the HKUST-1/Nb2CTx composite excellent potential in energy conversion and storage applications.

Molten salt-assisted synthesis of boron-doped carbon nitride for photocatalytic hydrogen evolution.

In this work, B and K were introduced into the heptazine structure of carbon nitride to synthesize the catalyst kalium-boron doped carbon nitride (KBCN) with a larger light absorption range and improved photogenerated carrier separation rate. Boron atoms are introduced into the carbon nitride heptazine units to optimize the electronic structure within the carbon nitride planes, and the B-N bonds formed by the heptazine units facilitate charge transfer. Potassium atoms are introduced into the carbon nitride interlayer as charge transfer channels to synergistically promote the transfer of photogenerated electrons. This work provides a potential idea for the doping of metallic and nonmetallic elements to jointly promote the charge distribution and transfer of carbon nitride.

Defect-Induced Atomical Zn-O/N-C Bonding Promotes Efficient Charge Transfer in S-Scheme Interface for Bubble Level Solar Hydrogen Production.

Establishing efficient and clear atomic-level charge transfer channels presents a significant challenge in the design of effective photocatalysts. A sound strategy has been developed herein involving the construction of defect-induced heterostructures that create chemical bonds serving as charge transfer channels at the heterojunction interface. In situ XPS, alongside theoretical calculations, demonstrates the successful construction of Zn-O/N-C as atomic charge transfer channels. Our findings reveal that the introduction of zinc vacancies (VZn) reduces the carrier transport activation energy (CTAE) from 155.2 meV for ZIS/CN to 128.7 meV for VZn-ZIS/CN. Consequently, the optimal VZn-ZIS/CN achieves a high hydrogen evolution rate of 22.26 mmol g-1 h-1 without Pt as a cocatalyst, which is approximately 57 times greater compared to that of ZIS/CN. Notably, hydrogen is generated at bubble levels under natural sunlight. This work provides insights into the mechanisms by which defect-induced heterostructure building strategies can introduce chemical bonds at the heterojunction interface.

Covalent Organic Frameworks for Boosting H2O2 Photosynthesis via the Synergy of Multiple Charge Transfer Channels and Polarized Field.

Covalent organic frameworks (COFs) serve as one of the most promising candidates for hydrogen peroxide (H2O2) photosynthesis, while attaining high-performance COFs remains a formidable challenge due to the insufficient separation of photogenerated charges. Here, through the rational design of bicarbazole-based COFs (Cz-COFs), we showcase the first achievement in piezo-photocatalytic synthesis of H2O2 using COFs. Noteworthily, the ethenyl group-modified Cz-COFs (COF-DH-Eth) demonstrates a record-high yield of H2O2 (9212 μmol g-1 h-1) from air and pure water through piezo-photocatalysis, which is ca. 2.5 times higher than that of pristine Cz-COFs without ethenyl groups (COF-DH-H) under identical condition and COF-DH-Eth without ultrasonic treatment. The H2O2 production rate originates from the synergistic effect between an ultrasonication-induced polarized electric field and the spatially separated multiple charge transfer channels, which significantly promote the utilization of photogenerated electrons by directional transfer from bicarbazole groups to the ethenyl group-modified benzene rings. Several Cz-COFs and bifluorenylidene-based COFs (COF-BFTB-H) with similar twisted monomers exhibit obvious piezoelectric performance for promoting H2O2 generation, signifying that organic ligands with a twistable structure play a crucial role in creating broken symmetry structures, thereby establishing piezoelectric properties in COFs.

Covalent Organic Frameworks for Boosting H2O2 Photosynthesis via the Synergy of Multiple Charge Transfer Channels and Polarized Field

AbstractCovalent organic frameworks (COFs) serve as one of the most promising candidates for hydrogen peroxide (H2O2) photosynthesis, while attaining high‐performance COFs remains a formidable challenge due to the insufficient separation of photogenerated charges. Here, through the rational design of bicarbazole‐based COFs (Cz‐COFs), we showcase the first achievement in piezo‐photocatalytic synthesis of H2O2 using COFs. Noteworthily, the ethenyl group‐modified Cz‐COFs (COF‐DH‐Eth) demonstrates a record‐high yield of H2O2 (9212 μmol g−1 h−1) from air and pure water through piezo‐photocatalysis, which is ca. 2.5 times higher than that of pristine Cz‐COFs without ethenyl groups (COF‐DH‐H) under identical condition and COF‐DH‐Eth without ultrasonic treatment. The H2O2 production rate originates from the synergistic effect between an ultrasonication‐induced polarized electric field and the spatially separated multiple charge transfer channels, which significantly promote the utilization of photogenerated electrons by directional transfer from bicarbazole groups to the ethenyl group‐modified benzene rings. Several Cz‐COFs and bifluorenylidene‐based COFs (COF‐BFTB‐H) with similar twisted monomers exhibit obvious piezoelectric performance for promoting H2O2 generation, signifying that organic ligands with a twistable structure play a crucial role in creating broken symmetry structures, thereby establishing piezoelectric properties in COFs.

Constructed 2D sandwich-like layer WO3/Ti3C2/ZnIn2S4 Z-scheme heterojunction by chemical bond for effective photocatalytic hydrogen production

Photocatalytic water-splitting has gained significant global attention in recent years. However, identifying effective photocatalysts remains challenging due to the rapid recombination of photoinduced charge carriers. In this study, two-dimensional (2D) sandwich-like layer WO3/Ti3C2/ZnIn2S4 photocatalysts were successfully fabricated using a simple anaerobic solvothermal process. The 2D Z-scheme heterojunction enhances rapid charge transport via TiS or TiOW bonds, serving as efficient charge transfer channels and minimizing the distance for interfacial photocarrier transfer. Consequently, the hydrogen production rate of 20 % WO3/Ti3C2/ZnIn2S4 composite reaches 7.39 mmol·g−1·h−1, which is 3.5 and 7.1 times higher than that of 20 % Ti3C2/ZnIn2S4 and pure ZnIn2S4, respectively. Furthermore, the hydrogen production rate of 20 % WO3/Ti3C2/ZnIn2S4 composite reaches 2.54 mmol·g−1·h−1 without the use of sacrificial agents. This work paves the way for designing 2D sandwich-like Z-scheme heterostructures through interfacial chemical bonds.

Programmed Charge Transfer in Conjugated Polymers with Pendant Benzothiadiazole Acceptor for Simultaneous Photocatalytic H2O2 Production and Organic Synthesis.

While being important candidate for heterogeneous photocatalyst, conjugated polymer typically exhibits random charge transfers between the alternating donor and acceptor units, which severely limits its catalytic efficiency. Herein, inspired by natural photosystem, the concept of guiding the charge migration to specific reaction sites is employed to significantly boost photocatalytic performance of linear conjugated polymers (LCPs) with pendant functional groups via creating programmed charge-transfer channels from the backbone to its pendant moiety. The pendant benzothiadiazole, as revealed in both in situ X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations, can act as electron "reservoir" that aggregates electrons at the active sites. Moreover, the presence of charge-transfer channels, evidenced by transient absorption spectroscopy (TAS), accelerates the electron transfer, preventing the recombination of electrons and holes. As a result, in this elaborately-designed architecture, the photogenerated electron can move smoothly towards the reduction sites, facilitating the reduction of O2 into H2O2, while remaining holes are directed to oxidation centers, simultaneously oxidizing furfuryl alcohol to furoic acid. The optimized photocatalyst LCP-BT demonstrates a competitive catalytic performance with H2O2 productivity of 868.3 μmol L-1 h-1 (9.8 times higher than conventional random charge-transfer polymer LCP-1) and furfuryl alcohol conversion over 95 % after 6 h.

Fabrication of Two-Dimensional B-Doped C3N4 Nanosheet-Encapsulated One-Dimensional Rod-like Mo-MOF-Derived MoS2 Heterojunctions for Enhanced Photocatalytic Ethanol Conversion and Synergistic Hydrogen Production

The photocatalytic conversion of ethanol and the simultaneous development of hydrogen technology play a role in solving the energy crisis and reducing environmental pollution. In this research, rod-like M-MoS2 serves as a channel for charge transfer, leading to superior photocatalytic activity compared to H-MoS2. Further, two-dimensional (2D) B-doped C3N4 (BCN) nanosheets were anchored on the one-dimensional (1D) rod-like M-MoS2 surface to form a 1D/2D heterojunction, with M-MoS2/BCN-0.08 (mass ratio of M-MoS2:BCN of 0.08:1) exhibiting the highest photocatalytic performance. Under visible light irradiation, the ethanol conversion rate reached 1.79% after 5 h of photocatalytic reaction per gram of catalyst, while generating 421 μmol of 2,3-butanediol (2,3-BDO), 5460 μmol of acetaldehyde (AA), and 5410 μmol of hydrogen gas (H2). This different characterization provides evidence that a significant amount of photoinduced electrons generated in BCN under illumination conditions rapidly transfer to the conduction band (CB) of M-MoS2 through the rod-like structure of M-MoS2, and finally transfer to Pt to promote the production of hydrogen gas. The photoinduced holes in the valence band (VB) of M-MoS2 are rapidly consumed by ethanol upon transferring to BCN, effectively separating the photoinduced electron–hole pairs and resulting in superior photocatalytic performance.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels

AbstractPhotocatalytic CO2 reduction serves as an important technology for value‐added solar fuel production, however, it is generally limited by interfacial charge transport. To address this limitation, a two‐dimensional/two‐dimensional (2D/2D) p‐n heterojunction CuS‐Bi2WO6 (CS‐BWO) with highly connected and matched interfacial lattices was designed in this work via a two‐step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p‐n heterojunction combination promoted the electron transfer from the Cu to Bi sites, leading to the coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in the BWO nanosheets facilitated the adsorption and activation of CO2, and the generation of high‐coverage key intermediate b‐CO32−, while CuS (CS) acted as a broad light‐harvesting material to provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p‐n heterojunction CS‐BWO exhibited average CO and CH4 yields of 33.9 and 16.4 μmol g−1 h−1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS‐BWO samples. This work provided an innovative design strategy for developing high‐activity heterojunction photocatalyst for converting CO2 into value‐added solar fuels.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels.

Photocatalytic CO2 reduction serves as an important technology for value-added solar fuel production, however, it is generally limited by interfacial charge transport. To address this limitation, a two-dimensional/two-dimensional (2D/2D) p-n heterojunction CuS-Bi2WO6 (CS-BWO) with highly connected and matched interfacial lattices was designed in this work via a two-step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p-n heterojunction combination promoted the electron transfer from the Cu to Bi sites, leading to the coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in the BWO nanosheets facilitated the adsorption and activation of CO2, and the generation of high-coverage key intermediate b-CO3 2-, while CuS (CS) acted as a broad light-harvesting material to provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p-n heterojunction CS-BWO exhibited average CO and CH4 yields of 33.9 and 16.4 μmol g-1 h-1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS-BWO samples. This work provided an innovative design strategy for developing high-activity heterojunction photocatalyst for converting CO2 into value-added solar fuels.

Design of highly responsive chemiresistor-based sensors by interfacing NiPc with graphene

Highly sensitive and selective gas-sensing materials are critical for applications ranging from environmental monitoring to breath analysis. A rational approach at the nanoscale is urgent to design next-generation sensing devices. In previous work, we unveiled interesting charge transfer channels at the interface between p-type doped graphene and a layer of nickel phthalocyanine (NiPc) molecules, which we believe could be successfully exploited in gas sensing devices. Here, we have investigated the graphene-NiPc interface’s response to adsorbed gas molecules via first-principles calculations. We focused on NH3 and NO2 as test molecules, representing electron donors and acceptors, respectively. Notably, we identified the Ni dz2 orbital as a key player in mediating the charge transfer and affecting the charge carrier density in graphene. As a proof-of-concept, we then prepared the graphene-NiPc system as a chemiresistor device and exposed it to NH3 and NO2 at room temperature. The sensing tests revealed excellent sensitivity and selectivity, along with a rapid recovery time and a remarkably low detection limit.

Multifunctional Triboelectric Metamaterials with Unidirectional Charge Transfer Channels for Linear Mechanical Motion Energy Harvesting

AbstractConventional triboelectric generators (TEGs) have been developed to mainly harvest the energy of linear mechanical motions and convert it usually into oscillating or pulsive, but not sustainable, electrical outputs. In this study, unidirectional charge transfer mechanisms are introduced to develop a triboelectric mechanical metamaterial (TMM) with sustainable electrical outputs. Density functional theory and experimental analyses demonstrate three minimum necessary components of TMMs fabricated by only two triboelectric materials (i.e., copper and PTFE) to generate sustainable electrical outputs. Under a wide range of compression‐tension strain of ±50%, the maximum open‐circuit voltage, short‐circuit current, and volumetric power density are 3860 V, 8 µA, and 365.3 kW m−3, respectively. Different from most conventional cellular solids, the mechanical energy dissipation of the TMMs increases quadratically with the unit cell number. High volumetric electromechanical efficiency is achieved when the unit cell is miniaturized. In addition to energy harvesting and mechanical energy dissipation, TMMs can sense the displacement by counting the number of distinctive peaks in the short‐circuit charge transfer or reaction force versus time curves. The extreme electromechanical functionalities of the TMMs facilitate their applications in intelligent suspension systems, miniaturized green power sources, and self‐sensing energy harvesters.

Effect of Synthesis Temperature on Performance of Phenazine-Based Cathode for Sodium Dual-Ion Batteries.

Organic materials have attracted much attention in the field of electrochemical energy storage due to their ecological sustainability, abundant resources and structural designability. However, low electrical conductivity and severe agglomeration of organic materials lead to poor discharge capacity and reaction kinetics in batteries. Herein, the morphology of the phenazine-based organic polymer poly(5,10-diphenylphenazine) (PDPPZ) was modified by varying the synthesis temperature. PDPPZ-165 °C with an exceptional porous structure provides abundant reaction channels for rapid charge transfer and diffusion that improves the reaction kinetics in sodium dual-ion batteries. Therefore, PDPPZ-165 °C cathode possesses excellent rapid charge-discharge capability delivering a specific capacity of 119.2 mAh g-1 at 40 C. Furthermore, a high specific capacity of 124.7 mAh g-1 can be provided even at a high loading of 16 mg cm-2 at 0.5 C with a capacity retention of 86.4 % after 500 cycles. This work could afford new insights for optimizing the performance of organic cathode materials in sodium dual-ion batteries.

Integrated Omnidirectional Design of Non‐Volatile Solid Additive Enables Binary Organic Solar Cells with Efficiency Exceeding 19.5 %

AbstractSolid additives have drawn great attention due to their numerous appealing benefits in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). To date, various strategies have been reported for the selection or design of non‐volatile solid additives. However, the lack of a general design/evaluation principles for developing non‐volatile solid additives often results in individual solid additives offering only one or two efficiency‐boosting attributes. In this work, we propose an integrated omnidirectional strategy for designing non‐volatile solid additives. By validating the method on the 4,5,9,10‐pyrene diimide (PyDI) system, a novel non‐volatile solid additive named PyMC5 was designed. PyMC5 is capable of enhancing device performance by establishing synergistic dual charge transfer channels, forming appropriate interactions with active layer materials, reducing non‐radiative voltage loss and optimizing film morphology. Notably, the binary device (PM6 : L8‐BO) treated by PyMC5 achieved a PCE over 19.5 %, ranking among the highest reported to date. In addition, the integration of PyMC5 mitigated the degradation process of the devices under photo‐ and thermal‐stress conditions. This work demonstrates an efficient integrated omnidirectional approach for designing non‐volatile solid additives, offering a promising avenue for further advancements in OSC development.

Integrated Omnidirectional Design of Non-Volatile Solid Additive Enables Binary Organic Solar Cells with Efficiency Exceeding 19.5 .

Solid additives have drawn great attention due to their numerous appealing benefits in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). To date, various strategies have been reported for the selection or design of non-volatile solid additives. However, the lack of a general design/evaluation principles for developing non-volatile solid additives often results in individual solid additives offering only one or two efficiency-boosting attributes. In this work, we propose an integrated omnidirectional strategy for designing non-volatile solid additives. By validating the method on the 4,5,9,10-pyrene diimide (PyDI) system, a novel non-volatile solid additive named PyMC5 was designed. PyMC5 is capable of enhancing device performance by establishing synergistic dual charge transfer channels, forming appropriate interactions with active layer materials, reducing non-radiative voltage loss and optimizing film morphology. Notably, the binary device (PM6 : L8-BO) treated by PyMC5 achieved a PCE over 19.5 %, ranking among the highest reported to date. In addition, the integration of PyMC5 mitigated the degradation process of the devices under photo- and thermal-stress conditions. This work demonstrates an efficient integrated omnidirectional approach for designing non-volatile solid additives, offering a promising avenue for further advancements in OSC development.