Negative Conduction Band Research Articles

Tailoring Interface via Tuning the Phase and Morphology of TiO2 for Efficient Mesoporous Perovskite Solar Cells.

The efficiency of mesoporous perovskite solar cells (mp-PSCs) is significantly influenced by favorable charge transport properties across their various interfaces. The interfaces involving compact-TiO2, mesoporous electron transport layer (ETL), and perovskite layer are particularly vital for high-performing devices. Our study presents a combined experimental and computational approach, specifically employing density functional theory, to explore the impact of mesoporous-ETL/perovskite interface properties on carrier transport. These properties are examined in relation to the phases and morphologies of the mesoporous layer. Different phases of TiO2, including anatase, rutile, and brookite, and various morphologies such as nanocubes, nanorods, and disks/clusters, were synthesized using a simple hydrothermal synthesis route. They constitute the mesoporous layer, and Cs0.05FA0.84MA0.14PbI2.55Br0.45 is used as the perovskite absorber in mp-PSCs. The performance of the resulting mesoporous-TiO2 (mp-TiO2) device was investigated in relation to the different phases and morphologies of mp-TiO2. The mp-PSCs with the anatase phase as the mesoporous ETL exhibited the highest device parameters, including power conversion efficiency of 19.15%, short-circuit current density of 22.55 mA/cm2, fill factor of 76.50%, and open-circuit voltage of 1.11 V. The superior performance of the anatase structure is attributed to its promising band edge alignment, which results from a small negative conduction band offset compared to other phases, thereby enhancing carrier transport. This study underscores the potential of interface optimization to improve device performance. By investigating the device performance across different phases and morphologies of the mp-TiO2 layer, we can pave the way for the design of next-generation energy devices.

Synthesis of CdS QDs/NH2-Nb2O5 via electrostatic self-assembly method for highly efficient photocatalytic removal of NO and synchronous inhibition of NO2

A two-step electrostatic self-assembly method was used to first graft –NH2 groups onto the Nb2O5 followed by loading of CdS QDs onto the NH2-Nb2O5 to obtain CdS/NH2-Nb2O5. The performance of the samples under visible light was evaluated under simulated conditions of 25 °C and varying relative humidity (RHs). The results showed that with the increase of RH, the NO removal efficiency by CdS/NH2-Nb2O5 increased first and then decreased, reaching the maximum NO removal efficiency when RH = 50 %. The selectivity of NO2 on CdS/NH2-Nb2O5 (9.01 %) was significantly lower compared to that of Nb2O5 (24.44 %) and NH2-Nb2O5 (19.72 %). The introduction of –NH2 groups and CdS QDs significantly enhanced visible light absorption and improved the separation efficiency of photogenerated charge carriers. In-situ DRIFTS analysis revealed that Cd2+ served as an additional active site for NO adsorption. Furthermore, CdS had a relatively negative conduction band position, which was conducive to the generation of O2–, further inhibiting the generation of NO2. This work provides a new approach to the design and preparation of catalysts for photocatalytic oxidation of NO.

Novel CoFe2O4 / LaAlO3 nanocomposites: An impressive photocatalyst with p-n hetero-junction for improved H2 generation under visible exposure

The present work is devoted to the synthesis of perovskite LaAlO3 by Sol-Gel approach and its application for the photo-evolution of H2 in conjunction with cobalt ferrite CoFe2O4 prepared by nitrate route. The thermal analysis (TG/DSC) showed that the formation is completed at 600 °C. The X-ray diffraction (XRD) pattern is characteristic of a single phase, crystallizing in a rhombohedral symmetry with a crystallite size of 36 nm. The SEM micrographs revealed a homogeneous structure with an agglomeration of shaped grains (40–80 nm). The forbidden band (3.39 eV), calculated from diffuse reflectance data, is assigned to the ligand charge transfer O2−: 2p → Al3+: 3s orbital. As prepared, LaAlO3 is an n-type semiconductor as demonstrated from the capacitance - potential (C−2 - E) graph with an electron density of 9.4 × 1014 cm−3 due to oxygen under-stoichiometry. Attention was directed to photo-electrochemistry in connection with water reduction into hydrogen. With a negative conduction band potential (−0.11 VSCE), H2 generation can be synergized over the hetero-system by visible light. The photocatalytic capability of CoFe2O4 25%/LaAlO3 revealed a high H2 generation of 963 μmol g−1 in the alkaline electrolyte (NaOH, 0.1 M) with a catalyst dose of 1 mg mL−1, which is 1.3 times more than CoFe2O4 under similar conditions. Photoactivity is significantly improved by 60%, up to 2400 μmol g−1 in the presence of oxalate C2O42− as a hole scavenger in the hetero-junction, two hydrogen release tests were successfully recorded. The higher H2 production in the hetero-junction system is attributed to the lower recombination rate of electron/hole (e−/h+) in the material, due to the large band bending at the solid interfacial.

Two-Level regulation photocatalytic activity of Bi2WO6/COFs with ligand engineering and piezoelectric field for Highly-Efficient degradation of antibiotics

Covalent organic frameworks (COFs) have attracted significant attention in photocatalytic water purification due to their structural designability and sufficiently negative conduction band edges. However, the limited oxidation capacity of single COFs and the low utilization rate of photogenerated carriers result in suboptimal catalytic activity. To address these challenges, we propose a two-level regulation strategy that involves ligand engineering and the introduction of a piezoelectric field to enhance the photocatalytic performance of COF-based photocatalysts. In this study, we combined the piezoelectric material Bi2WO6 with COFs modified with different ligands to design a series of Bi2WO6/R-COFs (R=H, F, CH3O) heterojunctions. Modifying COFs with –OCH3 functional group tuned the local electron distribution, thereby remarkably improving photogenerated electrons transfer rate constant. Besides, the incorporation of Bi2WO6 generated a piezoelectric field under ultrasound, which provides a strong driving force for photocatalytic. Meanwhile, the construction of the heterojunctions offered multi-channel for the generation of reactive oxygen species. As a result, the photocatalytic degradation rate of Bi2WO6/CH3O-COFs reached 93.5 % toward sulfamethoxazole within 48 min under ultrasound-coupled light irradiation, which is nearly three times higher than Bi2WO6/H-COFs. Furthermore, Bi2WO6/CH3O-COFs demonstrated superior degradation performance for other pollutants, including p-chlorophenol, bisphenol A, tetracycline, and phenol, with degradation efficiencies of 99.0 %, 98.4 %, 93.5 % and 88.1 %, respectively. This work proposes a two-level modulation strategy that significantly enhances the antibiotic degradation performance of COF-based catalysts, offering a new perspective for the design of photocatalysts for environmental remediation.

Facilitating charge transport by phenyl-substitution and sulfate-intercalation on carbon nitride tubes for highly efficient photocatalytic hydrogen evolution

Despite challenges still remain, simultaneous regulation of light absorption, carrier separation and efficient exposed active sites of carbon nitride for the photocatalytic production of hydrogen (H2) are essential to help alleviate the energy crisis and achieve carbon neutrality. Using in-plane phenyl groups doping and interlayer sulfate groups modification, we demonstrated an eco-friendly and facile method for excogitating porous tubular graphitic carbon nitride (PhSO-TCN2.5). The PhSO-TCN2.5 has hollow tubular morphology with ultrathin pore walls, which offers more exposed active sites, shortened charge diffusion path and readily available diffusion channels. More importantly, the in-plane phenyl groups doping and interlayer sulfate groups modification enabled significant intense the visible light absorption, accelerated carrier transfer due to the electron transport channel between the interlayers. Meanwhile, PhSO-TCN2.5 possesses exceptionally adjusted band gap structure and more negative conduction band potential. Accordingly, the above synergistic effects contribute to the efficient photocatalytic efficiency in H2 evolution to 8709.29 μmol g−1 h−1. In addition to the apparent quantum yield of 12.0% at 420 nm, that far exceeds the reported tubular and functional group-modified carbon nitride photocatalysts. This document offers guidance on designing and producing photocatalysts with high efficiency.

Efficient removal of high concentration organic pollutants by ZnIn2S4 with highly active sulfur vacancy

Metal sulfides have attracted much attention because of their wide light response range and negative conduction band (CB) position, which can generate abundant charges to participate reduction and oxidation reactions. In recent years, efforts are devoted to enhance the charge separation and transfer to improve its overall performance in photocatalytic applications. Herein, we synthesized zinc indium sulfide (ZnIn2S4, named as ZIS) with S vacancy (VS) defects via a hydrothermal method with assist of excess sulfur sources. All the as-prepared samples exhibited significant photocatalytic degradation performance on organic pollutants with high concentration. Among them, the VS-ZIS (TAA) demonstrated exceptionally high photodegradation activity under visible light (λ＞420 nm) irradiation, achieving removal rates up to 96 % and 90 % over TC (80 mg/L) and RhB (40 mg/L), respectively. Moreover, VS-ZIS (TAA) also displayed an excellent cycling stability. Combining experimental and theoretical studies, we unveil that the introduction of VS defects broadens the light absorption range, accelerates carrier separation and transfer, and provides additional surface active sites, thus improving the photocatalytic degradation efficiency. This study suggests that creating VS can induce effective charge separation, thus enhancing the photocatalytic activity and providing a viable pathway for treating high concentration organic pollutants.

Z-scheme promoted interfacial charge transfer on Cu/In-porphyrin MOFs/CdIn2S4 heterostructure for efficient photocatalytic H2 evolution

The rational modulation of charge transfer pathway within heterojunction is essential toward boosting photocatalytic activity for H2 production from water splitting Herein, the bimetallic-modified porphyrin MOFs (CuIn-PMOFs) crystals have been developed as a substrate for the epitaxial wrapping of CdIn2S4 (CIS) nanosheets via a facile solvothermal process to fabricate novel hierarchical CuIn-PMOFs@CdIn2S4 (CuIn-PMOFs@CIS) heterojunctions. The experimental results, combined with density-functional theory calculations, demonstrated that the CuIn-PMOFs have a more negative conduction band position and the electrons transfer pathway is inclined from CIS to CuIn-PMOFs, which leads to the formation of unique Z-scheme heterojunctions. Profiting from the special “O-In” charge transfer channel, extensive highly active photoinduced electrons areaggregated and depleted in the conduction band of CuIn-PMOFs, contributing to the improvement of H2 generation activity. Moreover, the heterojunction model also revealed the minimum Gibbs free energy for H* intermediate adsorption (ΔGH*). Concretely, the optimized composite displayed a maximum H2 evolution rate of 7527.54 μmol g–1h−1, which is around 13.12 and 6.63 times higher than that of pure CdIn2S4 and CuIn-PMOFs, respectively. This work aims to suggest that constructing distinctive Z-scheme modulated charge transfer mechanism is an advanced strategy for acquiring highly efficient photocatalysts.

Constructing GO films/CdS nanoparticles/MoS2 nanosheets ternary nanojunction with enhanced photocatalytic hydrogen evolution activity

CdS, as a visible-light responsible photocatalyst, has gained considerable attentions for its relatively narrow bandgap and negative conduction band edge. However, its photocatalytic activity is hindered by challenges such as severe charge recombination, insufficient active sites and poor stability. In this work, a robust strategy is proposed to optimize the transfer channel for charge carriers and enhance the active sites by heterojunction and cocatalyst engineering. The well-designed GO/CdS/MoS2 shows remarkable durability (20 h without significant loss of H2 production rate) with a high photocatalytic H2 production rate of 1.45 mmol h−1g−1 (about 6.6-fold enhancement compared with CdS) at GO content of 0.1 wt% and MoS2 loading amount of 5.0 wt%. The bolstered H2 production rate is attributed to the augmented transfer channels of mass owing to the holey structure of GO, the enhanced active sites since the introduction of MoS2, and the unidirectional transfer of electrons from CdS to MoS2, which is ascribed to the built-in electric field in the CdS/MoS2 interface. Thanks to the directional transfer of holes from CdS to GO in the GO/CdS interface, the assemblage of holes in CdS is prevented, thus contributing to the amplified stability GO/CdS/MoS2. Our findings offer insights for the enhanced photocatalytic activity of CdS based photocatalysts, which may inspire the development of the heterostructure photocatalysts for solar-to-fuel conversion.

Reinforced Electrons Transfer and Capture in S‐Scheme TiO2@Co(OH)F‐Pt Heterojunction for Excellent Solar Hydrogen Evolution

AbstractTiO2 with the merits of non‐toxicity, high stability, strong redox capability, and low cost, has garnered considerable attention in the fields of renewable energy. However, the practical application is limited by the rapid recombination of photogenerated electron–hole pairs, posing a challenge to enhance electron utilization without compromising catalytic activity. Herein, S‐scheme TiO2@Co(OH)F‐Pt heterojunction through a simple hydrothermal and photo‐deposition method is constructed. The experimental tests and theoretical computation indicate that Co(OH)F possesses a smaller work function and a more negative conduction band (CB) position, significantly accelerating the separation of photogenerated charge carriers. Furthermore, the built‐in electric field, band bending between TiO2 and Co(OH)F, and the electron sink of Pt nanoparticles, facilitate the reduction of protons to hydrogen. The as‐prepared TiO2@Co(OH)F‐Pt exhibits high‐performance solar hydrogen evolution with an evolution rate of 1401 µmol h−1. The apparent quantum yield (AQY) is determined to be 22.8% at a single wavelength of 365 nm. After reacting 12 h for three cycles, no noticeable performance degradation occurs, showing good stability of the catalyst. This work provides a rational strategy for the design of heterojunction photocatalysts for driving the production of new energy and useful chemicals.

Plant-Based Phytochemicals for Synthesis of Z-Scheme In2O3/CdS Heterostructures: DFT Analysis and Photocatalytic CO2 Reduction to HCOOH and CO.

Photocatalytic CO2 reduction shows potential for mitigating industrial emissions. Z-scheme In2O3/CdS(bio) heterostructures (25 nm, 217.0 m2 g-1 surface area) with a more negative conduction band synthesized using phytochemicals present in Aegle marmelos with short microwave irradiation inhibit CdS(bio) photocorrosion forming SO42-. In2O3/CdS(bio) increased the photocurrent density (0.82 μA cm-2) and CO2 adsorption (0.431 mmol g-1) significantly compared to CdS(bio) and In2O3(bio) NPs. Heterostructures increased decay time and reduced PL intensity by 46.28 and 61.80% over those of CdS(bio) and In2O3(bio) NPs. Density functional theory (DFT)-optimized geometry, band structure analysis, and density of states (DOS) studies indicate that the DOS of CdS is modified with In2O3 incorporation, enhancing charge separation. Optimal 0.4In2O3/CdS(bio) heterostructures exhibit remarkable CO2 conversion to HCOOH/CO production of 514.4/162 μmol g-1 h-1 (AQY 4.44/2.45%), surpassing CdS(bio) and In2O3(bio) by 9 and 6.5 times, and retain their morphological and structural stability. This study provides valuable insight for developing bio-based CdS heterostructures for photocatalytic CO2 reduction.

Bi, K co-doped graphitic phase carbon nitride for efficient photocatalytic H2O2 production

The emerging photocatalytic production of hydrogen peroxide (H2O2) using graphitic carbon nitride (g-C3N4) has attracted a lot of attention for its potential applications in various fields. However, However, the catalytic activity of pure g-C3N4 is still limited. Herein, Bi, K co-doped g-C3N4 (BixKy-CN) was prepared by co-thermal polymerization of a mixture of potassium nitrate, bismuth nitrate, melamine, and urea. The obtained Bi3.6K3-CN composite possesses more negative conduction and valence band positions that can, to some extent, enhance photocatalytic performance by lowering the energy barrier of redox reactions and by enhancing electron absorption capacity. Additionally, the pyrolysis process of the potassium nitrate and bismuth nitrate has a considerable impact on the formation of the morphology of g-C3N4, generating a porous lamellar-structure with nitrogen defects, resulting in increased oxygen adsorption and utilization capacity. These synergistic effects enable Bi3.6K3-CN to exhibit excellent photocatalytic activity and cycling stability for H2O2 production. After 3 hours of visible light irradiation, the production of H2O2 catalyzed by Bi3.6K3-CN can reach 1207.72 μmol L-1, which is 57 times higher than that of pure g-C3N4.

Effect of annealing temperature on bismuth vanadate nano thin films for solar cell applications

Bismuth vanadate (BiVO4) has been used as the photoanode electrodes in ferroelectric solar cells owing to its unique combination of properties: a narrow bandgap among ferroelectrics, economic viability, negative conduction band edge, and remarkable stability. The present work explores the fabrication and characterization of BiVO4 thin films prepared via spin coating, with a specific focus on elucidating the influence of the annealing temperature (400–550 °C) on their structural, optical, and photovoltaic properties. From X-ray diffraction (XRD) analysis, it is observed that higher annealing temperatures have promoted the formation of larger grains, enhanced crystallinity, and induced a preferred crystal orientation characteristic of the monoclinic scheelite structure. Tauc plot analysis shows the dependence of the optical band gap on the annealing temperature for BiVO4 thin films. The band gap values have decreased slightly from 2.50 eV at 400 °C to 2.44 eV at 550 °C. This is indicated by the slightly narrowed bandgap, which influences the structure of the material or defect states at higher annealing temperatures. A narrower bandgap allows for the absorption of lower-energy light, potentially improving the light absorption efficiency of BiVO4 thin films in photoanode applications. The influence of annealing temperature on BiVO₄ thin film solar cell performance was investigated further through the analysis of open-circuit voltage (Voc), short-circuit current (Isc) and power conversion efficiency.

A P-doped BiOBr nanosheet for enhanced photocatalytic CO2 reduction efficiency

The photocatalytic CO2 reduction efficiency of BiOBr is constrained by its insufficient ability to effectively absorb visible light, as well as its rapid photogenerated electron-hole complexation. Modulating the band gap and charge transfer kinetics of photocatalysts through heteroatom doping is an effective solution. P-doped BiOBr photocatalysts were synthesized through a one-step hydrothermal method to promote the photocatalytic reduction of CO2 in this investigation. The photocatalytic reduction of CO2 to CO using an 8 % P-BiOBr catalyst achieved a rate of 9.13 µmolg−1h−1, which is 3.3 times greater than that observed with the pure BiOBr catalyst. XPS, UV-Vis DRS and Mott-Schottky analyses revealed that P-BiOBr had a narrower forbidden bandwidth and a more negative conduction band, which improved the absorption of visible light and the reduction ability of CO2. Furthermore, The transient photocurrent response, electrochemical impedance spectroscopy (EIS), and photoluminescence (PL) spectra signify that the doping of phosphorus (P) enhances the separation and mobility of the carriers generated by light in BiOBr. This research offers a straightforward approach for doping with P, which enhances photocatalytic reduction of CO2 by semiconductor.

Revealing the reason for enhanced CZTSSe device performance after Ag heavily doped into absorber surface.

Ag-doping treatment is a popular method for enhancing the performance of kesterite-structured Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Among the various methods, incorporating a high concentration of Ag+ into an absorber surface has proven to be particularly effective. However, the exact mechanisms behind this improvement are still unclear. This study aims to investigate the key factors that improve device performance through simulation. Specifically, the influence of the change in the carrier density, CuZn antisite defects, interface defect density, and formation of an n-type AZTSSe surface after heavy surface Ag doping have been examined. The simulation results indicate that the formation of an n-type AZTSSe layer on an absorber surface can significantly improve the open circuit voltage (VOC) and overcome the efficiency saturation problem induced by severe interface recombination for CZTSSe devices with a negative conduction band offset (CBO), compared to other affecting factors. This is because the modified conduction band alignment and the realization of interface-type inversion reduce interface recombination and retard the Fermi level pinning. However, the formation of interface-type inversion does not significantly improve CZTSSe devices with a positive CBO, as these devices already have weaker interface recombination. This work implies that the formation of an n-type AZTSSe layer is crucial for further improving the performance of CZTSSe devices with a negative CBO and can pave the way for improving the performance of thin film solar cells with severe interface recombination.

Correlation between defect properties and the performance of eco-friendly CsSnI3-based perovskite solar cells

This study investigates the potential use of eco-friendly, all-inorganic cesium tin iodide (CsSnI3) perovskite (PVK) as an absorber layer. Despite having higher temperature stability of CsSnI3, the challenge is to get a uniform and defect-free film that hinders the performance. To accomplish this goal, we investigated several performance-related variables for perovskite solar cells (PSCs), including material defect density (Nt ), transport materials, layer thickness, temperature impacts, and back contact work functions. Negative valence band or conduction band offset values indicate no barrier preventing photogenerated carriers from flowing into the charge transport layers. The simulation result shows that hole transport layer thickness shows a higher impact than electron transport layer thickness. For the PVK thickness of 500 nm and a carrier density of 1018 cm−3, the device offers an optimum power conversion efficiency of 20.1%. The performance is more significantly affected by the defects in the PVK material compared to the defects present at the interface. Higher recombination (Re−h+) occurs at the TiO2–CsSnI3 interface. Defects located within the deep-level trap positioned at the mid-point of the band gap energy (E g) have a negative impact on the performance. The temperature coefficient (C T) is approximately ‒0.367% K‒1, indicating excellent thermal stability in an open environment. The selection of ‘A’ cation, the addition of additives, or carefully controlled fabrication techniques can mitigate the defect. This research shows the strategy for creating defects-free PSC devices, ultimately enhancing performance and the stability.

Diethanolamine-functionalized BiOI hollow microspheres with negative conduction bands maximize the visible light photocatalytic performance for CO2 reduction

Bismuth iodide oxides have a wide range of applications as visible light photocatalysts in CO2 reduction reactions. While formation of heterostructures between semiconductors has been actively used to enhance catalytic reduction performance, the functional groups used to improve the separation ability of electron/holes (e-/h+) and surface energy band positions of BiOI surfaces have been rarely mentioned. Here, a new modification strategy was reported to improve the photocatalytic performance using solvents with hydroxyl functional groups to change the surface structure of BiOI hollow microspheres. Intriguingly, the BiOI hollow microspheres functionalized using diethanolamine have a larger negative surface conduction band than BiOI. Thus the photogenerated electron reduction capacity of the diethanolamine-functionalized BiOI is greatly enhanced, which can be obtained from the yield of reduction reaction testing and characterization results. This hydroxyl functional group modified BIOI provides a new strategy for improving photocatalytic performance. The DFT simulation provides a theoretical basis for photocatalytic CO2 reduction.

Influence of oxygen content on the properties of In2(OxS1−x)3 used as buffer material in Cu(In,Ga)Se2 solar cells

We investigate magnetron-sputtered In2(OxS1−x)3 compounds acting as an alternative buffer system to the solution-grown CdS or Zn(O,S) buffer layers in Cu(In,Ga)Se2 (CIGS) thin-film solar cells. The influence of the oxygen content on the solar cell performance, microstructure of the mixed systems, bandgap, and band offsets to CIGS is investigated experimentally and also characterized by calculations based on density functional theory. Samples in a series with different chemical compositions ranging from In2S3 to In2O3 are either directly deposited from ceramic targets or from a pure In2S3 target by reactive sputtering by adding O2 in the Ar sputtering gas. The binary compounds In2S3 and In2O3 sputtered at 220 °C substrate temperature from ceramic targets exhibit a crystalline structure, whereas the ternary In2(O,S)3 compounds are either nanocrystalline in the case of In2(O0.25S0.75)3 or amorphous for In2(O0.5S0.5)3 and In2(O0.75S0.25)3. For [O]/([O] + [S]) ratios above 0.25, the cell efficiencies decrease drastically, mainly due to lower open-circuit voltages (VOC). This behavior can be explained by an increase of the negative conduction band offset between the CIGS absorber and the oxygen-rich In2(OxS1−x)3 or In2O3 buffer, resulting in pronounced VOC losses. Adding oxygen to In2S3 with optical bandgap energies of around 2 eV results in a bowing of the values to below 2 eV and finally reaching values of around 2.7 eV for In2O3 if an indirect band transition is assumed. In summary, our results reveal that pronounced oxygen incorporation in In2S3 is not beneficial in terms of CIGS device efficiency because oxygen is electronically inactive and poorly miscible.

Study on the photogenerted cathodic protection of Ti-P-V-O coating photoelectrode prepared by microarc oxidation method for 304 stainless steel

Photocathodic protection is a promotion strategy for the corrosion protection of metallic materials, and the selection of photocathodic materials is a critical factor in improving the performance of photocathodic protection of metallic materials. Herein, a Ti-P-V-O composite semiconductor photoelectrode with an adjustable porous structure was prepared by the micro-arc oxidation (MAO) method using titanium alloy (TC4) as the matrix and ammonium metavanadate (NH4VO3) as the additive. The photogenerated open circuit potential, instantaneous photocurrent density response value, electrochemical impedance spectroscopy, and Tafel curve of as-prepared Ti-P-V-O photo-electrodes were measured after coupling with 304SS to clarify the cathodic protection effect for 304 stainless steel (304SS). It is found that the as-prepared Ti-P-V-O coating photoelectrode has a more negative open circuit potential, a more significant photocurrent density response, more effective interface carrier transport ability, lower resistance, lower compounding efficiency of photogenerated electron/hole pairs, and more negative conduction band level, as compared with that of TiO2 coatings. Moreover, the optimized Ti-P-V-O photoelectrode (Ti-P-V-O&300 V) exhibited the maximum negative shift of the corrosion potential (410 mV vs. SCE) for coupling with 304 stainless steel. This work presents a new strategy for constructing an efficient coating photo-electrode for photocathodic protection of metallic materials.

Visible light-driven molecular oxygen activation for oxidative amidation of alcohols using lead-free metal halide perovskite.

Herein, we report the modulation of the band structures of halide perovskite Cs2CuBr4 by tuning the synthesis methods. The photocatalyst PC-1, synthesized by the hot injection method, has a more negative conduction band minima (CBM) than the photocatalyst PC-2, synthesized at room temperature. As a result, PC-1 can activate molecular O2 more efficiently to initiate the radical-mediated dehydrogenation of alcohols. The more positive valence band maxima (VBM) of PC-1 also facilitates amine oxidation to the corresponding radical. Further, improved charge separation and transport and a decrement in the photogenerated charge carrier recombination have been detected for PC-1 to enhance photocatalytic activity. PC-1 showed improved yields for a series of structurally diverse amides (highest yield = 98%) by oxidative amidation of alcohols under visible light irradiation.

Enhanced Photocatalytic Activity of Cs4PbBr6/WS2 Hybrid Nanocomposite

Photocatalytic processes are among the prime means for mitigating the pollution caused by toxic effluents. In this context, photocatalysis presents a promising path and is undergoing rapid evolution. Halide perovskite‐nanocrystals (HP‐NCs) are excellent candidates due to their negative conduction band minimum and low work function, essential for photocatalysis. Yet, HP‐NCs face limitations within this domain because they are prone to chemical degradation when exposed to external factors like high temperature, polar solvents, oxygen, and light. A practical approach toward stabilizing HP‐NCs involves hybridizing them with a chemically inert material that can provide steric stabilization and act as a cocatalyst. Transition‐metal dichalcogenides emerge as outstanding candidates to sterically stabilize the HPs as they are stable, chemically inert, and can serve as co‐catalysts, enabling suppressed charge recombination. Herein, the photocatalytic performance of Cs4PbBr6/WS2‐nanocomposites towards organic dye degradation in polar solvents under visible light illumination is investigated. We found that the presence of WS2 nanostructures significantly stabilizes the HP‐NCs and promotes dye degradation rate compared to pristine Cs4PbBr6‐NCs. Using transient absorption measurements, we found that the WS2‐nanostructures act as an electron transport channel, effectively reducing charge recombination in the NCs. These findings pave the way for implementing Cs4PbBr6/WS2‐nanocomposites as stable and superior photocatalysts.