Recombination Rate Of Charge Carriers Research Articles

Sonochemical surface modification of a novel Sm2O3@g-C3N4@Bi2O3 ternary hybrid photocatalyst exhibiting efficient solar light harvesting: Degradation of Azure b and photoelectrochemical water splitting

Engineered Z-scheme photocatalysts have a strong redox activity while also reducing the annihilation of light-induced charge bearers. In this investigation, a solid state twin Z-scheme Sm2O3@g-C3N4@Bi2O3 nanocomposite has been successfully prepared employing bismuth (III) nitrate, samarium chloride and urea as precursor chemicals in a single co-calcination procedure followed by sonochemical surface modification. The formation of flower like multiphasic material is confirmed from SEM and HRTEM images. BET findings suggested the enhancement in specific surface area of Sm2O3@g-C3N4@Bi2O3 and reduced band gap from UV–visible data. Photoluminescence results confirmed the reduction in rate of charge carrier recombination of Sm2O3@g-C3N4@Bi2O3. Presence of samarium is confirmed from XPS analysis. Under direct solar radiation, the surface modified Sm2O3@g-C3N4@Bi2O3 hybrid demonstrated amplified photo-assisted catalytic activity for the degradation of Azure B (AzB) than pristine g-C3N4 and their binary composite Sm2O3@g-C3N4. It is possible to attribute the better solar light absorption, higher separation efficacy of photo-promoted electron-holes to the amplified photo-assisted degradation performance of the Sm2O3@g-C3N4@Bi2O3 composite. The photodegradaton of AzB follows pseudo-first order kinetics and the observed rate constants are 0.0014, 0.0026, and 0.0316 min−1 for g-C3N4, Sm2O3@g-C3N4, and Sm2O3@g-C3N4@Bi2O3 ternary composite. The nanocomposite also demonstrates good stability and recyclability. A unique solid-state twin Z-scheme photocatalytic pathway was also hypothesized in light of the findings. The fabricated ternary hybrid shown efficient photoelectrochemical water splitting reaction for H2 and O2 generation.

Superior visible-light absorbing Ag@ZnO nanorods hybrid photocatalyst for efficient decomposition of commercial pharmaceuticals tetracycline and amoxicillin

This work assesses the role of the noble metal silver in the visible-light sensitization of UV-active ZnO by introducing a localized plasmonic resonance effect and enhancing the spatial charge carrier separation. We herein synthesize ZnO nanorods via a solvothermal approach, yielding nanorods of length and diameter 1.356 ± 0.619 μm and 120.56 ± 25.09 nm, respectively. Silver nanoparticles are reduced on the surface of ZnO nanorods via the photodeposition route. XRD spectra reveal a high crystallinity and wurtzite-type structure for ZnO with new peaks for cubic phase Ag upon Ag-loading. The diffraction peaks shift upon Ag modification, indicating partial incorporation of Ag into the ZnO lattice. Further, upon Ag-decoration, a slight increase in dislocation density and micro strain is obtained, which could suppress the recombination rate of charge carriers. The DRS spectra reveal a band gap contraction of materials from 3.19 to 2.98 eV with increasing Ag density. The PL spectra confirmed that the optimum Ag concentration of 3 wt% is proficient in harvesting visible light towards high photocatalytic degradation efficiencies of tetracycline (92.1 %) and amoxicillin (76.4 %) in 90 min as compared to 49.4 % and 38 % over pristine ZnO nanorods. TOC studies reveal only partial mineralization of ∼42.7 % (tetracycline) and ∼31.3 % (amoxicillin) due to the formation of reaction intermediates identified by HR-MS chromatograms. In addition, degradation pathways are proposed through the fragments at different m/z ratios.

Box–Behnken Design and experimental studies on novel fibrous g-C3N4 towards water splitting and degradation of indigo carmine dye

Graphitic carbon nitride (g-C3N4) is robust and stable metal free polymeric materials that have recently gained interest towards photocatalytic applications. It shows visible-light driven photocatalytic activity with a major drawback of higher recombination rate of charge carriers and moderate oxidation ability. These issues are overcome by structural modifications using facile polymerization of acidized melamine thus controlling the structure of graphitic carbon nitride. The major factors affecting the photocatalytic activity were experimentally optimized and effect of these parameters was evaluated using the Box–Behnken Design of response surface methodology. The fabricated fibrous graphitic carbon nitride (NFgCN) shows a superior activity of 81.0 μmol g−1 h−1 hydrogen generation and 99.9 % degradation of indigo carmine (IC) dye in 90 min. The NFgCN shows 5 times higher activity for hydrogen generation compared to the pristine g-C3N4.

Anthracene-based dual channel donor-acceptor triazine-containing covalent organic frameworks for superior photoelectrochemical sensing

Covalent organic frameworks (COFs) exhibit excellent photoelectrically active structures and serve as channels for photon capture and charge carrier transport. However, their relatively high charge-carrier recombination rates and lack of specific recognition sites limit their application in photoelectrochemical sensing. This paper reports a functionalized donor–acceptor (D-A) COF comprising electron-rich polycyclic aromatic moieties and electron-deficient triazines (Tz) incorporating boronic acid through ligand exchange. The number of aromatic rings in the polycyclic aromatic moiety is crucial for establishing an efficient D-A system within COF. In the absence of an external electron donor, the anthracene-based COF exhibited a five-fold enhancement in photocurrent compared to the naphthalene-based COF. The resulting anthracene-based D-A COF exhibited enhanced orbital overlap and electron push–pull interactions, facilitating more effective charge separation. Furthermore, introducing boronic acid enabled the selective enrichment of low-concentration external electron donors, such as dopamine, in the inner Helmholtz plane. This ingenious approach establishes a unique dual-channel D-A system that allows direct measurement of dopamine in serum. Under optimized conditions, the test platform achieves good correspondence for dopamine at 1 to 100 nM and 0.5 to 100 μM with a detecting limit of 0.36 nM (3σ/S, n = 11). This strategy introduces a novel dimension to photoelectrochemical sensing, focusing on the effect of spatial separation between the external electron donor and the photoelectrode interface that intricately shapes the behavior and enhances the performance of the photoelectric system.

Photocatalytic oxidative-extractive desulfurization of dibenzothiophene under simulated solar light with MoS2-CeO2/Al2O3-SiO2 nano photocatalyst: effect of CeO2 content

In this paper, a visible light-driven nanophotocatalyst of MoS2 with different amounts of CeO2 (0%, 8%, 16%, 24%, and 32% wt.) was impregnated on SiO2-Al2O3. The physicochemical properties of synthesized photocatalysts were investigated by XRD, FESEM, TEM, UV-Vis DRS, PL, BET-BJH, ICP-OES, EDX, and FTIR analyses. While the size of particles in all samples was in the nanoscale range, the sample with 8% wt. of CeO2 indicated the narrowest particle size distribution. UV-Vis DRS and PL analyses confirmed that adding CeO2 to the MoS2/SiO2-Al2O3 photocatalyst increased the amount of light absorption and decreased the recombination rate of charge carriers. Among CeO2-containing samples, the sample with 8% wt. of CeO2 illustrated the lowest recombination rate and the narrowest bandgap energy of 2.9 eV. The MoS2-CeO2/SiO2-Al2O3 photocatalyst with 8% wt. of CeO2 had the highest adsorption of DBT in dark conditions (29.93%), the highest photodegradation (96.9%) after 3 h of visible light irradiation and good stability after five consecutive runs. Meanwhile, total sulfur measurement indicated that using this sample and the extraction afterward, the model fuel has lost 96% of its sulfur content which confirms the excellent ability of acetonitrile-assisted extraction in gathering desulfurization products from the fuel.

Organic pollutant degradation for micro-molecule product emission over SiO2 layers-coated g-C3N4 photocatalysts.

In this study, a SiO2 layer-coated g-C3N4 catalyst was prepared by a sol-gel method to overcome the poor adsorption ability and high recombination rate of charge carriers of pristine g-C3N4. SEM and TEM images indicated that SiO2 nanoparticles were coated on the surface of g-C3N4 nanoparticles with a layered structure and the layers were tightly contacted with g-C3N4. XRD patterns, FTIR spectra, UV-vis spectra and XPS spectra revealed that the structure of g-C3N4 was not destroyed and its photoelectric catalytic properties were not suppressed by the coating of SiO2 layers. Adsorption experiments revealed that the SiO2 layers improved the adsorption performance of g-C3N4 and their ratios were adjusted. The molecular weights of the final products of the degradation of RhB and antibiotics were at the micro-molecule level while the amount of g-C3N4 reached 1.2% of the mass fraction, which were more suitable for pollutant degradation compared with those of g-C3N4 due to its poor adsorption ability. The reason for this was likely that the SiO2 layers were not only beneficial for the adsorption of pollutants and intermediate products but also for prolonging the life time of the separated electrons and holes. Finally, active trapping experiments confirmed that both the holes and superoxide radicals were the main factors in the degradation of RhB and antibiotics, with the superoxides being the most active species.

Structurally and surficially activated TiO2 nanomaterials for photochemical reactions.

Renewable fuels and environmental remediation are of paramount importance in today's world due to escalating concerns about climate change, pollution, and the finite nature of fossil fuels. Transitioning to sustainable energy sources and addressing environmental pollution has become an urgent necessity. Photocatalysis, particularly harnessing solar energy to drive chemical reactions for environmental remediation and clean fuel production, holds significant promise among emerging technologies. As a benchmark semiconductor in photocatalysis, TiO2 photocatalyst offers an excellent solution for environmental remediation and serves as a key tool in energy conversion and chemical synthesis. Despite its status as the default photocatalyst, TiO2 suffers from drawbacks such as a high recombination rate of charge carriers, low electrical conductivity, and limited absorption in the visible light spectrum. This review provides an in-depth exploration of the fundamental principles of photocatalytic reactions and presents recent advancements in the development of TiO2 photocatalysts. It specifically focuses on strategic approaches aimed at enhancing the performance of TiO2 photocatalysts, including improving visible light absorption for efficient solar energy harvesting, enhancing charge separation and transportation efficiency, and ensuring stability for robust photocatalysis. Additionally, the review delves into the application of photodegradation and photocatalysis, particularly in critical processes such as water splitting, carbon dioxide reduction, nitrogen fixation, hydrogen peroxide generation, and alcohol oxidation. It also highlights the novel use of TiO2 in plastic polymerization and degradation, showcasing its potential for converting plastic waste into valuable chemicals and fuels, thereby offering sustainable waste management solutions. By addressing these essential areas, the review offers valuable insights into the potential of TiO2 photocatalysis for addressing pressing environmental and energy challenges. Furthermore, the review encompasses the application of TiO2 photochromic systems, expanding its scope to include other innovative research and applications. Finally, it addresses the underlying challenges and provides perspectives on the future development of TiO2 photocatalysts. Through addressing these issues and implementing innovative strategies, TiO2 photocatalysis can continue to evolve and play a pivotal role in sustainable energy and environmental applications.

Significantly advanced hydrogen production via water splitting over Zn/TiO2/CNFs and Cu/TiO2/CNFs nanocomposites

Photocatalytic water splitting using solar radiation has drawn considerable attention for production of hydrogenbecause of minimal carbon emissions, however huge limitations that still exist are low light harnessing catalysts and high recombination rate of the photo-generated charge carriers. This study focuses on the fabrication of nanomaterials for advanced photocatalytic water splittingas a result, structures of TiO2/CNFs, Cu/TiO2/CNFs, and Zn/TiO2/CNFs nanocomposites of mesoporous nature were synthesized using CNFs and surfactant wrapping sol–gel/hydrothermal method. Impregnation technique was used in copper and zinc loading while characterization of the synthesized catalysts was achieved by XRD, Raman, FESEM, TEM, UV/DRS, BET, FTIR, XPS, and PL techniques. Water splitting was performed byUV light irradiation and the effect of compositing TiO2/CNFs-Cu/Znevaluated. 10 %_TiO2/CNFs/5%Zn composite was the most efficient photocatalyst for hydrogen production when compared with the rest of the samples. 10 %_TiO2/CNFs/5%Zn, 0.53 mol (h g cat.)-1, was 90–100 folds the amount generated over commercial TiO2 – P25, and pure TiO2photocatalysts. The improved photo-activity of the TiO2/CNFs, Cu/TiO2/CNFs, and Zn/ TiO2/CNFs composites were due to the synergistic effect between Cu, Zn and CNFs.This work gives promising route for fabricating TiO2/CNFs/metal (Cu, Zn) composites for advanced H2production using UV-radiation.

Enhanced photocatalytic degradation of tetracycline using NiCo–BiVO4 nanocomposite under visible light irradiation: A noble-metal-free approach for water remediation

The increasing pollution of water bodies with organic contaminants, including antibiotics, has become a significant environmental concern. In this study, a noble-metal-free alternative, NiCo bimetal cocatalyst, was synthesized and applied to enhance the photocatalytic degradation of the antibiotic tetracycline (TC) using BiVO4 as the photocatalyst under the visible spectrum. The NiCo–BiVO4 nanocomposite exhibited improved visible light absorption, reduced recombination rate of charge carriers, and enhanced electrochemical properties. The photocatalytic degradation of TC was significantly enhanced by the NiCo bimetal modification, with the 2 wt% NiCo–BiVO4 nanocomposite achieving an 87.2% degradation of TC and 82% Total Organic Carbon (TOC) removal within 120 min. The degradation kinetics of TC (target compound) followed a first-order reaction, with photogenerated electrons and holes identified as the primary active species responsible for the degradation process. The recyclability of the catalyst was also demonstrated for multiple runs, indicating its stability. Furthermore, the pathway of TC degradation by 2 wt% NiCo–BiVO4 nanocomposite was proposed based on the detected intermediate products using LC-MS analysis. This study provides a promising approach for developing efficient, noble-metal-free photocatalysts to remove organic contaminants from water sources.

A novel nickel-doped photoactive nanocomposite materials for the application of wastewater treatment

We have reported an efficient and novel nanocomposite structure of nickel (0.5 %, 1.0 %, 1.5 %, 2.0 % and 2.5 %) doped Fe3O4@rGO which is prepared by a simple chemical co-precipitation technique for degradation of methylene blue. In the current study, reduced graphene oxide (rGO) is chosen as the electron mediator for NiFe3O4/rGO nanocomposite catalyst to construct a binary photocatalytic system. The analysis of structural and optical properties supports their nano size, formation of nanocomposite material, doping of nickel ions into the characteristic inverse spinel cubic structure of Fe3O4 and the existence of synergistic effect between NiFe3O4 and rGO. Methylene blue was considered as a model dye during the investigation of the Photocatalytic activity of NiFe3O4/rGO. From the kinetic measurements, the reaction rate was predicted to play a key role in the process of degradation. This discussion also highlights the absorption peak extension towards the visible region and the energy band gap value decreases with increasing the nickel dopant concentration in novel NiFe3O4/rGO nanocomposite material. Transition metal doping significantly enhances the degradation efficiency and reduces the recombination rate of charge carriers which makes the NiFe3O4/rGO nanocomposite material a potential candidate for the degradation of methylene blue from wastewater. As indicated by all the nanocomposites, photocatalytic activity was higher than the pure Fe3O4 photocatalyst, and the highest photodegradation of 96.3 % MB within 30 min irradiation under visible light was shown by the 2.0 % of nickel-doped Fe3O4@rGO. In addition, the study examined the photodegradation process and photocatalytic reaction kinetics of MB.

Decoration of silver on ZnS for enhancement of sunlight-driven photodegradation of reactive red azo dye and norfloxacin antibiotic

High charge carrier recombination rate is the major difficulty affecting low photocatalytic performance of the UV-responsive ZnS photocatalyst. To overcome the problem, well dispersion of noble metals on the ZnS surface can be regarded as one of the useful strategies to enhance the photocatalytic efficiency. This is due to a synergy of creation of heterojunction structure and surface plasmon resonance effect. In the present work, the surface of the hydrothermally grown ZnS photocatalyst was modified with 10 wt %silver. The hexagonal Ag/ZnS photocatalyst provided high sunlight-active photocatalytic performance toward removal of anionic azo dye and norfloxacin antibiotic with the efficiency of about 99 % and 70 %, within 120 min, respectively. The improvement of the resultant photoactivity is attributed to increasing of charge separation capacity at the interface. Well distribution of silver on ZnS surface results in the generation of the Schottky barrier at the Ag/ZnS interface. This will end up with the increment of quantum efficiency and enlargement of the photocatalytic activity. Additionally, after modification of ZnS surface by addition of silver, a red shift in the light absorption toward visible region was found. This is assigned to the effect of surface plasmon resonance (SPR) of Ag on ZnS surface. The synthesized Ag/ZnS reveals high structural stability with enhanced performance even after the fifth cycle. This work demonstrates a new avenue for creation of a silver-modified ZnS for complete degradation of toxic organic contaminants including dyes and antibiotics by use of the abundant solar energy.

Cu-ZnO/CdS/rGO tertiary heterojunction for improved photocatalytic degradation of synthetic dyes using visible light

A novel tertiary heterojunction based on Cu-ZnO/CdS/rGO was successfully designed and produced from graphite, Zn2+. Cu2+, and Cd2+ precursors. The produced materials underwent thorough characterization, including microstructure, surface charges, chemical groups, elemental composition, as well as optical properties. The Cu-ZnO/CdS/rGO photocatalytic system exhibited a response to visible light, with an Eg = 1.8 eV, leading to a capability of generating efficient charge carriers by visible light irradiation. The combination of Cu-ZnO/CdS/rGO led to a reduction in recombination rate of charge carriers. Various factors such as pH, catalyst load, pollutant concentration, and reaction time, were methodically investigated for their influence on photocatalytic degradation of Direct Blue 71 (DB 71).The developed Cu-ZnO/CdS/rGO heterojunction exhibited a significant improvement in decomposition yield compared to individual components (from 1.26 to 2.0-fold). Under optimal conditions (pH 6.5 and 500 mg/L catalyst load), over 93 % of 0.05 g/L DB 71 were decomposed in just 100 min by visible light catalyzed by Cu-ZnO/CdS/rGO system, and the decomposition process fit the best the pseudo-1st-order kinetics, with coefficients in the range of 0.889 to 0.983. The primary species responsible for DB 71 degradation was the (O2•-), revealing that graphene sheets of reduced graphene oxide (rGO) might play an important role for electron transfer and react with dissolved O2 molecules to generate O2•-. This research introduces an innovative method to develop an efficient and feasible photocatalytic system, offering potential for use in practical wastewater treatment systems dealing with synthetic dye contamination.

C3N4-BiOBr/PVC photocatalytic submerged membrane for oil-in-water emulsion separation with visible light-driven self-cleaning performance

Membrane separation has been widely used for oil-in-water separation, but the fouling of oil droplets on the membrane surface is still a challenge. Coating a photocatalyst layer on the membrane surface is an effective method for the regulation of hydrophobicity, degradation of stuck oil, and boosting the self-cleaning properties of the membranes. Thus, in this work, a heterostructure photocatalyst of carbon nitride-bismuth oxybromide (C3N4-BiOBr) with different proportions was coated on a polyvinyl chloride (PVC) layer and the performance of the resultant membrane was studied in the separation of oil-in-water emulsion under visible light. The experimental results exhibited that the membrane with C3N4 to BiOBr ratio of 40:10 coating had the lowest water contact angle of 42°, the maximum light harvesting, the lowest surface roughness, and the low recombination rate of charge carriers. The correlations drawn between surface morphology and fouling behavior of this membrane led to the maximum flux of 65 L·m−2·h−1, 99% separation efficiency, 100% Total Organic Carbon (TOC) removal, and excellent self-cleaning properties (flux recovery ratio of 93.8%). Therefore, this study provides a novel design strategy for multifunctional membranes that achieve effective treatment of oil-in-water emulsion wastewater.

Two-dimensional CsPbI3/CsPbBr3 vertical heterostructure: a potential photovoltaic absorber

First-principles methods have been employed here to calculate structural, electronic and optical properties of CsPbI3 and CsPbBr3, in monolayer and heterostructure (HS) (PbI2-CsBr (HS1), CsI-CsBr (HS2), CsI-PbBr2 (HS3) and PbI2-PbBr2 (HS4)) configurations. Imaginary frequencies are absent in phonon dispersion curves of CsPbI3 and CsPbBr3 monolayers which depicts their dynamical stability. Values of interfacial binding energies signifies stability of our simulated heterostructures. The CsPbI3 monolayer, CsPbBr3 monolayer, HS1, HS2, HS3 and HS4 possess direct bandgap of 2.19 eV, 2.73 eV, 2.41 eV, 2.11 eV, 1.88 eV and 2.07 eV, respectively. In the HS3, interface interactions between its constituent monolayers causes substantial decrease in its resultant bandgap which suggests its solar cell applications. Static dielectric constants of all simulated heterostructures are higher when compared to those of pristine monolayers which demonstrates that these heterostructures possess low charge carrier recombination rate. In optical absorption plots of materials, the plot of HS3 displayed a red shift and depicted absorption of a substantial part of visible spectrum. Later on, via Shockley-Queisser limit we have calculated solar cell parameters of all the reported structures. The calculations showed that HS2, HS3 and HS4 showcased enhanced power conversion efficiency compared to CsPbI3 and CsPbBr3 monolayers when utilized as an absorber layer in solar cells.

Enhanced visible-light activation of persulfate for the removal of RhB by supported nano-(C,N,B)-tridoped TiO2/copper foam mixed-crystals.

Photocatalytic persulfate activation by TiO2 and its application in sewage treatment have aroused great interest because of its high decontamination ability and strong adaptability, but the low light energy utilization rate and poor recycling of TiO2 limited its practical application. Herein, by using C-, N-, and B-modified TiO2 and immobilizing it on copper foam, we prepared a new and efficient (C,N,B)-TiO2/copper foam photocatalyst with enhanced visible-light activation performance of persulfate for the removal of RhB. It almost completely degraded RhB within 15min of UV-vis light photocatalysis-assisted persulfate oxidation reaction with TOC removal of 53.17% in 30min and presented the excellent long-term recyclability and stability, which is much better or comparative than those photocatalysts in the related literatures. (C,N,B)-TiO2/copper foam exhibited the largest apparent rate constant (0.149min-1), 1.16 times higher than (C,N,B)-TiO2 (0.128min-1), and 2.40 times higher than that of TiO2 (0.062min-1), respectively. C,N,B doping modified the crystalline phase of TiO2, narrowed its band gap, and reduced charge-carrier recombination rate. These, together with the synergistic effect between photocatalysis and persulfate activation for enhancing generation of active species, jointly promoted the performance enhancement of TiO2. The 1O2 was the primary oxidation active species for the degradation of RhB, and the radical species (SO4•-, •O2-, and •OH) could further accelerate the photocatalytic activation of persulfate reaction.

Incorporating photocatalytic fuel cell with dual S-scheme CuBi2O4/Bi2WO6/ZnO NRA photoanode for energy recuperation from municipal wastewater treatment under sunlight

Photocatalytic fuel cell (PFC) utilized the chemical energy contained in the molecules by combining photocatalytic treatment of wastewater with fuel cell electrochemical reaction. Herein, a PFC system with a novel dual S-scheme heterojunction CuBi2O4/Bi2WO6/ZnO nanorod array (CBO/BWO/ZnO NRA) composite photoanode was first constructed for municipal wastewater treatment accompanied with electricity generation under direct sunlight. The introduction of CBO and BWO not only contributed to the narrowing of the band gap which enabled the ZnO NRA to utilize sunlight more efficiently, but also led to the excellent electron-hole segregating capability. The 10% CBO/BWO/ZnO NRA composite photoanode achieved a significantly ameliorated electrical power with maximum power density of 7.707 µW/cm2, which was superior to those pristine ZnO NRA and BWO/ZnO NRA binary materials. The composite photoanode was then tested for its mineralization activity in the municipal wastewater and 98.4% of COD removal was acquired within 90 min. The main attribution that conducive to its spectacular performance in municipal wastewater treatment came from the one-dimensional nanorod array architecture along with the synergistic relation among the three efficient components in the CBO/BWO/ZnO NRA heterojunction that can effectively hinder the charge carrier recombination rate and facilitated a good route for electron transport. The composite photoanode also manifested good stability in five cyclic runs. The dual S-scheme CBO/BWO/ZnO NRA enabled the free active species partook in the photoelectrocatalytic reaction and the working principle of PFC system was also speculated. Additionally, phytotoxicity findings signified that the comprehensive toxicity of municipal wastewater was eliminated after PFC treatment.

Crystal structure, mechanical, electronic, optical and thermoelectric characteristics of Cs2MCl6 (M = Se, Sn, Te and Ti) cubic double perovskites

The crystal structure, mechanical, electronic, optical and thermoelectric characteristics of Cs2MCl6 (M = Se, Sn, Te and Ti) cubic double perovskites are studied within GGA, GGA-mBJ and EV-GGA functionals. The M − Cl bond lengths are shorter and especially in Cs2TiCl6 double perovskite, which reflects the strong interaction between M and Cl atoms and this is correlated with its better chemical stability. The negativity of formation energy and Helmholtz free energy and no imaginary phonon modes throughout the Brillouin zone confirm the thermal, thermodynamic and dynamical stability of these double perovskites. Semiconductors Cs2MCl6 (M = Se, Sn, Te and Ti) double perovskites with flat conduction and valence bands, and an indirect band gap are p-type carriers. A high Seebeck coefficient, adequate ZT values ​​and non-toxicity make these compounds attractive for thermoelectric applications at high temperature and spintronic technology. The empty first conduction band corresponds to their band gap, and the transition occurs from Cl-p to (Se-p, Sn-p, Te-p and Ti-d). The high static dielectric constant and the intense peak of the real part in the ultraviolet energy range favor less the recombination rate of charge carriers and their use in optoelectronic devices. The indirect band gap, high absorption in ultraviolet energy, high static refractive index make these cubic double perovskites as ideal materials for solar cell applications.

Comparison of Modification Methods of Photocatalyst G-C3N4 in Hydrogen Production Performance

Non-metallic polymer semiconductor graphite phase carbon nitride (g-C3N4) is a low-cost, environmentally friendly raw material with suitable bandgap width and stable chemical properties. However, there are still problems such as lower surface area, higher recombination rate of photo-excited charge carriers, and lower utilization rate of visible light. This paper introduces the structure, physicochemical properties, preparation methods, and modification ideas of graphite phase carbon nitride, focusing on several popular modification achievements in recent years, as well as a horizontal comparison of their respective production methods, mechanisms, and hydrogen production efficiency. Finally, the challenges and prospects in the modification of carbon nitride are discussed.

Influence of nickel doping and cotton stalk activated carbon loading on structural, optical, and photocatalytic properties of zinc oxide nanoparticles

In the current study, the photodegradation of brilliant green (BG) dye has been studied in relation to the comparative photocatalytic activity of pure ZnO and Ni-doped ZnO/CSAC (cotton stalk activated carbon), which was produced using a chemical precipitation method. The structural, optical, morphological, and functional characteristics of Ni-doped ZnO/CSAC have been investigated. The XRD patterns demonstrated the hexagonal wurtzite structure of the Ni-doped ZnO/CSAC sample. The XPS scan supported a Ni2+ oxidation state for the Ni ions incorporated into the ZnO lattice. The optical features of the Ni-doped and loaded sample demonstrated a red shift in the light absorption and reduced the recombination rate of charge carriers. The FE-SEM was used to examine the morphology of the synthesized all the samples, and EDAX spectroscopy was used to determine their composition. In comparison to pure ZnO, Ni doped, and Ni (0.075 M) doped ZnO/CSAC exhibited a greater photocatalytic degradation of 91.47 % after 120 min under visible light irradiation. This result suggests that Ni-doped ZnO/CSAC may be an effective wastewater treatment material.

Photovoltaic efficiency enhancement via magnetism

The efficiency of photovoltaic cells has long been a subject of intense concern and research. Diverse photovoltaic cell types have been developed, including crystalline silicon cells (achieving up to 27.6% efficiency), multijunction cells (reaching up to 47.4% efficiency), thin film cells (attaining up to 23.6% efficiency), and emerging photovoltaic cells (exhibiting up to 33.7% efficiency). Despite advancements, achieving high efficiency on an industrial scale remains a significant challenge due to factors like charge carrier recombination rate, defects, temperature’s influence, etc. Numerous approaches have been explored to address these challenges, encompassing strategies such as incorporation of nanoparticle within the active layer, studying transport properties and defects using ion beams, utilizing magnetite materials, and leveraging the application of magnetic fields. The influence of a magnetic field can amplify the generation of charge transfer states exhibiting triplet characteristics, increasing the charge separation time. However, magnetic fields introduce spin-based effects, enabling the investigation of interactions between electron spins and magnetic fields through state-of-an-art synchrotron radiation techniques like XMCD. Several innovative cell configurations have reported substantial efficiency enhancements under the influence of magnetic fields. Examples include TiO2-BiFeO3 dye-sensitized cells, polymer-based cells with Fe3O4@PANI additives integrated into TiO2-based dye-sensitized cells, and the incorporation of Fe-doped SnO2 within the active layer of heterojunction organic solar cells. In this perspective review, the profound impact of magnetism on enhancing efficiency in photovoltaic cells has been analysed and the utilization of advanced X-ray absorption spectroscopic techniques to probe and comprehend these intricate effects.