Efficient Charge Carrier Transfer Research Articles

Z-Scheme Enabled 1D/2D Nanocomposite of ZnO Nanorods and Functionalized g-C3 N4 Nanosheets for Sustainable Degradation of Terephthalic Acid.

The urgent need to mitigate water pollution and achieve Sustainable Development Goal 14 (SDG 14)-Life below water, necessitates developing efficient and eco-friendly wastewater treatment technologies. This research addresses this challenge by photocatalytic degradation of terephthalic acid, a precursor for PET bottles using environment-friendly and biocompatible photocatalysts. The 1D/2D nanocomposite comprising zinc oxide (ZnO) nanorods and functionalized graphitic carbon nitride (Zn-TG) nanosheets were synthesized and thoroughly characterized. The nanocomposite effectively mitigated the individual drawbacks of Zn-TG agglomeration and the wide band gap of ZnO as confirmed through zeta potential and Tauc's plot studies, respectively. The synthesized nanocomposite achieved ~100 % degradation within 60 minutes, exhibiting superior kinetics (~2.5 times) compared to pristine samples. The enhanced degradation efficiency was elucidated by efficient charge carrier transfer (~5 times faster) and separation (~2 times improved) as confirmed through electrochemical impedance spectroscopy and time-resolved photoluminescence studies. The proposed Z-scheme pathway provides mechanistic insights. This proposed mechanism is supported by extensive electron paramagnetic resonance (EPR) and scavenger studies. The liquid chromatography-mass spectrometry (LC-MS) analysis confirms the formation of less toxic byproducts for ensuring that the wastewater treatment process is efficient and environmentally friendly. This research helps in developing a highly effective and sustainable wastewater treatment technology.

Hydrogen bond-induced supramolecular self-assembly strategy to fabricate ultra-dispersed Cu-loaded porous tubular graphitic carbon nitride with rich nitrogen vacancies and CuNx sites for efficient photo-Fenton catalysis

The low utilization of visible light and easy recombination of charge carriers of graphitic carbon nitride (CN) restrain its application as photo-electron donor and metal site support in photo-Fenton system. Herein, a hydrogen bond-induced supramolecular self-assembly strategy was created to fabricate an ultra-dispersed Cu-loaded porous tubular CN composite (CA-Cu/TCN) by the hydrothermal–pyrolysis method with citric acid (CA) as initiator and chelating agent. CA-Cu/TCN with rich nitrogen vacancies (NVs) and abundant ultra-dispersed CuNx sites exhibited narrow bandgap, favorable visible light absorption capability, and high separation and transfer efficiency of charge carriers. CA-Cu/TCN effectively catalyzed the activation of H2O2 for generating abundant reactive oxygen species under visible light irradiation, contributing to efficient degradation of ciprofloxacin (CIP) with removal rate of 95.9 % and kinetic rate constant of 0.0948 min−1. The superior catalytic activity of CA-Cu/TCN can be ascribed to the effective transport of photogenerated electrons, high specific surface area, atomically dispersed Cu species, and enriched surface NVs. The mechanism of photo-Fenton catalytic degradation of CIP and possible degradation pathways were proposed as the dominant role of 1O2. Toxicity evaluation of CIP and intermediates indicated that the degradation of CIP was a gradual detoxification process. This work offers a novel self-assembly strategy to design and synthesize highly active and sustainable visible light-driven photo-Fenton catalysts for effectively degrading organic pollutants.

Highly enhanced photocatalytic hydrogen production via GO-modified Cu-TiO2 system for dehydrogenation of alcohols under UV & sunlight irradiation

The high efficiency of the production of hydrogen from alcohols is vital to the advancement of energy technology. This study thoroughly investigates the process of alcohol dehydrogenation utilising GO-modified Cu-TiO2 photocatalyst under UV light and sunlight exposure. GO-modified Cu-TiO2 photocatalyst was synthesised using the hydrothermal method. Various experimental techniques, including FESEM, HRTEM, XPS, and DRS, confirmed the formation of the ternary composite. The influence of different alcohols (methanol, ethanol, propanol) and their concentrations (same vol% and molarity) on the amount of hydrogen (H2) production was examined in this study. The study thoroughly investigated the impact of various parameters, such as the influence of GO and Cu loading on TiO2 and their combined effect, time course, nature of alcohol and the reaction conditions on the photocatalytic hydrogen production. The GO(0.5 wt%)/Cu(3 wt%)-TiO2 (G0.5C3T) composite demonstrated the highest quantity of hydrogen production during methanol dehydrogenation when subjected to both UV and sunlight irradiation. The composite exhibited remarkably about three-fold higher hydrogen evolution in sunlight(881 mmol) than in UV light(294 mmol). The exceptional performance of this composite can be attributed to the efficient transfer of charge carriers and the delayed recombination of electron-holes, which is a result of the cooperative effect of GO and Cu deposited over the TiO2 system. This approach offers a proactive strategy, signifying the synergetic effect of loading GO and Cu over TiO2 to enhance the photocatalytic hydrogen production, which is regarded as a green fuel solution, and turns these materials into useful energy sources by using inexpensively synthesised photocatalysts.

MoC nanoparticles embedded in superior thin g-C3N4 nanosheets for efficient photocatalytic activity

Photogenerated charge carrier transfer efficiency in graphitic carbon nitride (g-C3N4) based heterostructures depended strongly on the interface nature. In this paper, MoC nanoparticles less than 5 nm were implanted in superior thin g-C3N4 nanosheets to create high charge carrier separation and transfer efficiency. Cubic MoC in N-doped graphitic carbon was first fabricated using dicyandiamide and ammonium molybdate tetrahydrate at 800 °C. The MoC nanoparticles were homogeneously implanted in g-C3N4 nanosheets by further thermal polymerization of bulk g-C3N4 prepared using melamine and MoC/C composites to create a Schottky junction which was confirmed by band gap analysis and free radical capture test. Melamine and dicyandiamide also play important role to create highly efficient catalysts. The MoC nanoparticles revealed fine crystallinity. A well-developed interface between MoC and g-C3N4 was observed. Because of high conductivity of MoC, well-developed interface, and co-catalyst role of MoC, the MoC/g-C3N4 junction exhibited ideal photocatalytic activity for dye degradation and water splitting. The kinetic constant rate of Rhodamine B degradation using a MoC/g-C3N4 sample created by optimized conditions was 0.061 min−1 which was 8.7 times of that of pristine g-C3N4 nanosheets. In the case of without co-catalyst addition, the photocatalytic hydrogen generation rate using this composite sample was 233.0 μmol g−1 h−1 which was 15.2 times of that of initial g-C3N4 nanosheets. These results supply an efficient approach for the first time to homogeneously distribute small cubic MoC nanoparticles in superior thin g-C3N4 nanosheets to construct heterostructures and greatly reduce photogenerated charge carrier recombination.

Rational synthesis of core/shell heterostructured quantum dots for improved self-powered photodetection performance enabled by energy band engineering

Colloidal quantum dots (CQDs), especially core-shell QDs, have attracted dramatic interests as emerging materials in optoelectronic devices due to their size tuneable band-gap, high absorption coefficient, facile and low-cost synthesis routing, etc. However, the precise design of core/shell band engineering along with charge carrier transfer efficiency are still challenging, inevitably impacting the performance of optoelectronic devices. Herein, three different types of CdSe/CdS core-shell heterostructured QDs have been obtained via a proposed synthesis strategy of adjusting the core size but fixing the shell thickness. The performance of the core-shell QDs based self-powered photodetectors can be efficiently regulated by the optimization of synthesis strategy with the design of energy band alignment. Compared to the quasi type-II and the type-I QDs devices, the Ilight/Idark ratio of type-II heterostructure based photodetector is increased by ∼2 and ∼5 orders of magnitude, respectively. The champion device exhibits extraordinary optoelectronic performance in terms of ultrahigh light-to-dark current ratio of 105, photoresponsivity of 10.64 mA/W, at bias of 0 V, respectively. The charge carrier dynamics and transfer mechanisms of the QDs were further investigated, revealing the improved carrier separation and transportation efficiency induced by a strong build-in electric field in type-II CdSe/CdS core-shell heterostructure. This work provides a new strategy for the next-generation self-powered QDs optoelectronics enabled by the proposed synthesis approach along with the design of energy band alignment.

Self-coupling of electron acceptor units in conjugated microporous polymers strengthening local donor-acceptor interaction for improving photocatalytic activity

The partial self-coupling of donor or acceptor unit during donor-acceptor (D-A) type CMPs synthesis is often overlooked for the effect on photocatalytic activity. Herein, we developed three D-A type CMPs, named SATE-CMP-n (n=1–3), which were constructed from triazine (TEPT) unit (A) and three salen units (D). With the rigidity of salen units increasing (the rigidity: salen-1 <salen-2 <salen-3), the self-coupling proportion of TEPT decreases. The experiments and DFT calculations reveal that salen-1 has the stronger electron-donating ability compared to salen-2 and salen-3, and that the self-coupling of TEPT units also enhances the electron-accepting ability. Therefore, SATE-CMP-1 exhibits the strongest D-A interaction and the highest separation and transfer efficiency of charge carriers, and has been used a photocatalyst for S−S and S−N coupling reactions. This work proves that the self-coupling of monomers in the construction of CMPs is not overlooked for adjusting the photocatalytic activity of catalyst.

N–ZnO/g-C3N4 nanoflowers for enhanced photocatalytic and electrocatalytic performances

In this study, CNNZO (N–ZnO/g-C3N4) nanocomposites were synthesized via a facile hydrothermal method and characterized using XRD, FTIR and FESEM. The resulting N–ZnO nano-needles and plate-like structures, anchored onto g-C3N4 agglomerates, formed distinctive nano-flower topography. CNNZO demonstrated superior photocatalytic activity compared to CN and N–ZnO, achieving ∼98 % degradation of Methylene Blue, 85.53 % of Methyl Green and 87.29 % of Methyl Orange under visible light irradiation within 90 min. This enhanced performance is attributed to the unique morphology of CNNZO, which promotes efficient charge carrier transfer and inhibits recombination. Additionally, CNNZO exhibited improved electrocatalytic activity with smaller HER and OER potentials. This study underscores the potential of CNNZO nanocomposites as effective catalysts for the degradation of organic contaminants and hydrogen and oxygen evolution for energy production.

Visible-light-driven photocatalytic degradation of tetracycline using citric acid and lemon juice-derived carbon quantum dots incorporated TiO2 nanocomposites

Tetracyclines (TC) are consistently found in aquatic ecosystems, contributing to the development and spread of antibiotic resistance genes and antibiotic-resistant bacteria. This poses adverse effects on aquatic organisms and humans, emphasizing the need for an effective approach to remove these contaminants. TiO2-based photocatalysts hold great potential for efficiently removing TC from water. This study aimed to synthesize TiO2 nanocomposites incorporated with carbon quantum dots (CQDs) derived from both artificial and natural sources. The nanocomposites were characterized using X-ray diffraction, electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and N2 adsorption–desorption test. The incorporation of CQDs into TiO2 resulted in the reduction of the band gap energy from 3.17 eV in pure TiO2 to 3.10 eV, broadening the light absorption range, and improving the charge carrier transfer efficiency. Continuously generated electrons led to the production of reactive oxygen species, predominantly •O2–, contributing to TC degradation. Holes and •OH radicals also played a significant role in TC degradation. As a result, CQDs/TiO2 nanocomposites exhibited 91.5 % TC removal under visible light irradiation (λ ≥ 400 nm) for 120 min at pH 8. The active sites of TC molecules were determined through density functional theory calculations, and the corresponding degradation pathways of TC were proposed using liquid chromatography-mass spectrometry. Furthermore, this study attempted to synthesize CQDs using lemon juice, showcasing the potential of these eco-friendly photocatalysts for TC removal. The visible-light-driven degradation of TC by the natural-source-derived CQDs/TiO2 nanocomposites demonstrated their applicability in water treatment to effectively address current environmental challenges.

Vacuum-assisted reforming cathode interlayer orientation for efficient and stable perovskite solar cells

The cathode interlayer (CIL) is vital for enhancing the performance of inverted (p-i-n) perovskite solar cells (PSCs) by preventing charge recombination and ion diffusion, thereby achieving superior efficiency. Herein, we introduce cost-effective perylene-diimide (PDI)-based CILs—PDIN-S, PDIN, and PDIN-L—with varying spacer lengths. Among them, PDIN-S exhibits exceptional attributes in thermal evaporation processability, optical absorbance, and charge transfer capabilities. Molecular orientations of PDIN-S are studied through two deposition techniques: vacuum thermal evaporation (VE) and spin-coating (SC). The face-on orientation observed in PDIN-S (VE) confers significant advantages, including improved π–π stacking, efficient charge carrier transfer, reduced interfacial resistance, and inhibited ion diffusion. Furthermore, PDIN-S (VE) also lowers the energy barrier towards cathode, boosting PSC efficiency to 23.82%. Moreover, it enhances both thermal and light stability, maintaining over 90% initial efficiency for 2036 h at 85 °C and sustaining 80% efficiency for 1848 h under continuous illumination. Our application of a straightforward VE method enables the manipulation of molecular orientation, resulting in a concurrent enhancement of efficiency and stability. These findings underscore the potential of PDIN-S as a promising component for highly efficient and stable PSCs.

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.

Ligand doping engineering induced robust internal electric field in MOFs/BiVO4 photoanode for water splitting

A robust internal electric field (IEF) within heterojunctions is essential for enhancing the separation and transfer of photogenerated charge carriers during photoelectrochemical (PEC) water splitting. In this contribution, a ligand doping engineering approach is innovatively proposed to design 3,5-Th2-TzH = 3,5-di(thiophen-2-yl)-1H-1,2,4-triazole (CuMTZ)/BiVO4 photoanodes, in which thiophene-containing electron-rich ligands (3,5-Th2-TzH) strengthen the interactions between CuMTZ and BiVO4. This results in the formation of a robust IEF, which serves as a strong driving force for efficient charge carrier transfer and separation, leading to an enhanced photovoltage. Furthermore, the uniform CuMTZ nanolayers act as a cocatalyst that not only increases the number of active reaction sites but also boosts photogenerated holes injection into the electrolyte to participate directly in the water oxidation process. Consequently, CuMTZ/BiVO4 photoanode exhibits a significant 4.26-fold improvement in photocurrent for water oxidation compared to BiVO4. This work highlights the significance of ligand doping engineering in the design of metal-organic framework (MOF)/semiconductor photoanodes for enhancing PEC efficiency.

Photoresponse, thermal and electrical behaviors of MXene-based polysulfone nanocomposite

The Ti3C2Tx MXene nanosheet was prepared by 40% (v/v) hydrofluoric acid etching at 20 °C for 48 h and delamination of bulk MAX Ti3AlC2 precursor material. A 2D nanomaterial MXene Ti3C2Tx as a nanofiller was introduced to polysulfone (PSulfone) matrix. MXene and PSulfone/MXene nanocomposite systems were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, Fourier-transform infrared and thermogravimetric analysis instruments. Dielectric and electrical characterization of PSulfone/MXene nanocomposite was carried out. The electrical resistance of Ti3C2Tx MXene from measurement current (I)–voltage (V) was measured as 116 Ω. Pure PSulfone matrix exhibits typical insulator behavior, and MXene exhibits a good conductor behavior. But, when MXene was added to the pure PSulfone matrix, the resistance of the MXene/PSulfone nanocomposite increased moderately compared to that of pure MXene. In spite of the excess of surface functional groups, MXene showed surprisingly good electron transport across the surface, while in the case of PSulfone/MXene nanocomposite, the insulating behavior of PSulfone significantly reduced the electron transport of MXene. The semiconductor behavior of PSulfone/Ti3C2Tx MXene nanocomposite indicates that MXene provides efficient charge carrier transfer in the nanocomposite system. By comparing the TGA results between the PSulfone and different weight ratios of PSulfone/Ti3C2Tx MXene nanocomposites, it was determined that MXene nanosheets had a significant effect in slightly accelerating the thermal degradation of PSulfone. Optical conductivity was investigated by preparing a film of PSulfone/MXene nanocomposite on an interdigital contact. It was observed that the optical current values changed depending on the increasing illumination intensity. Considering current–voltage measurements, the photocurrent generation potential of PSulfone/MXene nanocomposite shows that it can be used in photodevice production.

Built-in electric field mediated S-scheme charge migration in COF/In2S3 heterojunction for boosting H2O2 photosynthesis and sterilization

The construction of step-scheme (S-scheme) heterojunctions has emerged as a widely adopted strategy for achieving photocatalytic hydrogen peroxide (H2O2) generation. In this study, we employed an approach to deposit indium sulfide (In2S3) onto a Schiff-base covalent organic framework (COF), namely TpMA, for H2O2 photosynthesis and its sterilization application. The optimized photocatalyst, 10%TpMA/In2S3, exhibited remarkable photocatalytic performance, yielding a substantial H2O2 output of 311.07 μmol/L. A series of advanced instrumental analyses and density functional theory (DFT) results indicated that the establishment of the S-scheme heterojunction played a pivotal role in facilitating efficient charge carrier transfer and separation. Specifically, the formation of a built-in electric field was probed and quantified. Furthermore, the H2O2 exhibited the capability to undergo direct catalysis by Fe(II), which substantially facilitated the inactivation of pathogenic bacteria. This work unveils insight into the COF-based S-scheme photocatalysts and offers a sustainable approach for environmentally friendly H2O2 production for sterilization purposes.

A Multifunctional Hydrogen Bond Bridge Interface to Achieving Efficient and Stable Perovskite Solar Cells

AbstractIn perovskite solar cells (PSCs), the buried interface between the electron transfer layer (ETL) and perovskite (PVK) layer profoundly affects the charge carrier transfer efficiency, which has significant implications for the efficiency and long‐term stability of the device. Herein, an organic chemical compound 4,6‐diamino‐2‐mercaptosine (DMP) is incorporated into the ETL/PVK interface in order to optimize the interfacial performance through a hydrogen bond bridging junction. DMP is tightly anchored to the ETL surface by forming the intermolecular hydrogen bonding with the structure as N─H∙∙∙N. This bridge connection is beneficial for enhancing the interface contact, further restraining severe nonradiative charge recombination. Synchronously, the interaction of ─SH with uncoordinated Pb2+ passivates the defects on the bottom layer of perovskite, further regulating the perovskite crystal growth. Overall, the results express that the power conversion efficiency (PCE) of PSCs based on the DMP interface has significantly increased to 21.65% without obvious hysteresis. Meanwhile, the unencapsulated modified devices show superior environmental stability, maintaining over 85% of their initial PCE even after 500 h in an atmospheric environment.

Facile synthesis of Pd nanoparticles dispersed polypyrrole-carbon black/NiO nanocomposite with enhanced photocatalytic degradation of colored and colorless organic pollutants

Creation and designing of efficient visible-light responsive photocatalysts requires highly precise and extremely determined efforts in order to obtain material with promising properties and efficient transfer of charge carriers. In this work, we aim to develop and manufacture a distinct visible light photocatalyst consisting of NiO nanostructures, polypyrrole doped carbon black (PPyC) and Pd nanoparticles for wastewater treatment. The Pd NPs and PPyC doped NiO trio photocatalyst was developed via simple ultrasonication and photoreduction methods. XRD analysis showed that NiO has crystalline face centered cubic structure while the successful development of ternary photocatalyst was smoothly confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) studies. Transmission electron microscopy (TEM) images showed that NiO possessed fine irregular shape particles with size ranging from 20 to 50 nm grown abundantly in huge density, while the PPyC exhibited beads shape structures interconnected with each other giving chain like appearance. The diffuse reflectance UV–vis spectra showed red shift and lowering in bandgap upon Pd and PPyC doping. The newly produced Pd-PPyC@NiO photocatalyst has been exploited for the photocatalytic removal of colorless insecticide imidacloprid and colored methylene blue (MB) dye under visible light irradiation. The newly created Pd-PPyC@NiO photocatalyst removed 96.0% of imidacloprid just in 20 min representing ⁓ 3 times more efficient than bare NiO. Furthermore, Pd-PPyC@NiO photocatalyst was exceptionally well towards the destruction of MB under same visible light source, indicating its potential use in photocatalysis.

Thermally Induced Orderly Alignment of Porphyrin Photoactive Motifs in Metal-Organic Frameworks for Boosting Photocatalytic CO2 Reduction.

Efficient transfer of charge carriers through a fast transport pathway is crucial to excellent photocatalytic reduction performance in solar-driven CO2 reduction, but it is still challenging to effectively modulate the electronic transport pathway between photoactive motifs by feasible chemical means. In this work, we propose a thermally induced strategy to precisely modulate the fast electron transport pathway formed between the photoactive motifs of a porphyrin metal-organic framework using thorium ion with large ionic radius and high coordination number as the coordination-labile metal node. As a result, the stacking pattern of porphyrin molecules in the framework before and after the crystal transformations has changed dramatically, which leads to significant differences in the separation efficiency of photogenerated carriers in MOFs. The rate of photocatalytic reduction of CO2 to CO by IHEP-22(Co) reaches 350.9 μmol·h-1·g-1, which is 3.60 times that of IHEP-21(Co) and 1.46 times that of IHEP-23(Co). Photoelectrochemical characterizations and theoretical calculations suggest that the electron transport channels formed between porphyrin molecules inhibit the recombination of photogenerated carriers, resulting in high performance for photocatalytic CO2 reduction. The interaction mechanism of CO2 with IHEP-22(Co) was clarified by using in-situ electron paramagnetic resonance, in-situ diffuse reflectance infrared Fourier transform spectroscopy, in-situ extended X-ray absorption fine structure spectroscopy, and theoretical calculations. These results provide a new method to regulate the efficient separation and migration of charge carriers in CO2 reduction photocatalysts and will be helpful to guide the design and synthesis of photocatalysts with superior performance for the production of solar fuels.

NdCo3 Molecular Catalyst Coupled with a BiVO4 Photoanode for Photoelectrochemical Water Splitting

Photoelectrochemical water splitting is a promising strategy for harvesting and converting solar energy to green hydrogen energy. However, the current inferior performance restricts further improvement of the solar-to-hydrogen efficiency. In this work, a molecular catalyst [NdCo3(btp-3H)2(Ac)2(NO3)2] (NO3)·2H2O (referred to as NdCo3 herein) was deposited onto a porous BiVO4 photoanode using a drop-casting method, and the molecular catalyst was held in place on the BiVO4 surface via intermolecular forces. The photoelectrochemical water oxidation performance of the BiVO4/NdCo3 photoanode reached 2.25 mA cm–2 at 1.23 V vs RHE under AM 1.5G illumination (100 mW cm–2), which was much higher than the pristine BiVO4 photoanode (1.49 mA cm–2). The enhanced performance could be attributed to the improvement of the charge carrier transfer efficiency, resulting in the acceleration of the water oxidation kinetics and inhibiting charge carrier recombination. In addition, the electrocatalytic properties of the homogeneous system were also studied. It was found that a heterogeneous catalytic film was formed due to the water solubility of NdCo3, which enabled a long electrolysis process to be maintained. The electrocatalytic performance of a homogeneous system reached 1 mA cm–2 at 2.31 V vs RHE and was different from the heterogeneous catalytic film (reached 1 mA cm–2 at 2.10 V vs RHE). This integrated system showed that the combination of a molecular catalyst with a photoelectrode helped to promote charge-carrier transport and separation, reducing the amount of charge-carrier recombination. Our approach may be applicable to other materials, helping to provide ideas for developing material combinations capable of achieving greater solar-to-hydrogen efficiencies.

Construction of Zn vacancy mediated ZnS/Cu2−xS heterostructure via cation exchange reactions for broadband photocatalytic water splitting

Vacancy engineering has attracted great attention as the construction of defects can modify bandstructure and enhance photoabsorption ability by introducing additional vacancy energy levels, thereby achieving efficient photocatalytic H2 evolution activity. In this work, zinc-vacancy ZnS/Cu2−xS (ZnS-VZn/Cu2−xS) photocatalyst was successfully prepared by surface modification of ZnS-VZn. The presence of zinc vacancies endows visible light responsiveness of ZnS, which can be attributed to the two-photon absorption mechanism and demonstrated by the upward PL spectra. Cu2−xS would tightly anchor the surface of ZnS-VZn after the cation exchange reaction, which is good for the efficient transfer of charge carriers. Furthermore, Cu2−xS broadens the light absorption range of the ZnS-VZn/Cu2−xS composite and can generate more photoexcited charge carriers under visible light irradiation, resulting in outstanding photocatalytic H2 generation activity. As a result, the optimum photocatalytic H2 generation rate of 642.30 μmol g−1 h−1 was obtained over ZnS-VZn/Cu2−xS, which is 10.34 times higher than the pure ZnS-VZn. Additionally, ZnS-VZn/Cu2−xS composite exhibits excellent photostability over four cycles totaling 16 h and the charge transfer route is further confirmed by the in-situ XPS. The present work deepens the understanding of vacancy defects and provides a feasible method to rationally establish a semiconductor photocatalyst for efficient H2 generation from water splitting.

Binary Microcrystal Additives Enabled Antisolvent‐Free Perovskite Solar Cells with High Efficiency and Stability

AbstractDeveloping a facile method to prepare high‐quality perovskite films without using the antisolvent technique is critical for upscaling production of perovskite solar cells (PVSCs). However, the as‐prepared formamidinium (FA)‐based perovskite films often exhibit poor film quality with high density of defects if antisolvent is not used, limiting the photovoltaic performance and long‐term stability of derived PVSCs. Herein, this work adopts pre‐synthesized 3D methylammonium lead chloride (MAPbCl3) and 1D 2‐aminobenzothiazole lead iodide (ABTPbI3) microcrystals into self‐drying perovskite precursors, which serve as seed crystals to promote nucleation and growth of FAPbI3‐based perovskites without requiring antisolvent extraction. The combined binary microcrystals facilitate the formation of a dense and pinhole‐free perovskite film with a stable perovskite lattice and defect‐healed grain boundaries, enabling efficient charge carrier transfer and reduced non‐radiative recombination loss. As a result, the best‐performing inverted architecture device exhibits a champion power conversion efficiency of 23.27% for small‐area devices (0.09 cm2) and 21.52% for large‐area devices (1.0 cm2). These values are among the highest efficiencies reported for antisolvent‐free PVSCs. Additionally, the unencapsulated device shows enhanced moisture, thermal, and operational stabilities, and maintains 92% of its initial efficiency after being held at the maximum power point for 1000 h.

Piezotronic Effect Induced Schottky Barrier Decrease to Boost the Plasmonic Charge Separation of BaTiO3-Au Heterojunction for the Photocatalytic Selective Oxidation of Aminobenzyl Alcohol.

Charge carrier transfer efficiency as a crucial factor determines the performance of heterogeneous photocatalysis. Here, we demonstrate a simple nanohybrid structure of BaTiO3-Au (BTO-Au) for the efficient selective oxidization of benzyl alcohol to benzaldehyde upon piezotronic effect boosted plasmonic photocharge carrier transfer. With the aid of ultrasonic mechanical vibration, the reaction rate of the photocatalytic organic conversion would be considerably accelerated, which is about 4.2 and 6.2 times higher than those driven by sole visible light irradiation and sole ultrasonication, respectively. Photoelectrochemical tests under ultrasonic stimuli reveal the BTO-Au catalytic system is independent of the light intensity, showing a consistent photocurrent density, over a wide range of incident light brightness. The largely enhanced photocatalytic activity can be ascribed to the synergetic effect of surface plasmonic resonance (SPR)-piezotronic coupling by which a built-in electric field induced by the piezotronic effect significantly favors the oriented mobilization of energetic charge carriers generated by the SPR effect at the heterojunction. Notably, a decrease of the Schottky barrier height of ∼0.3 eV at the BTO-Au interface is verified experimentally, due to the band bending of BTO induced by the piezotronic effect, which can greatly augment the hot electron transfer efficiency. This work highlights the coupling of the piezotronic effect with SPR within the BTO-Au nanostructure as a versatile and promising route for efficient charge transfer in photocatalytic organic conversion.