Suitable Band Gap Energy Research Articles

Photo Electrocatalytic Water Splitting Using Sn Doped In2S3 Homologous Series Synthesized in Oxygen Deficient Flame

AbstractThe innovative development of reactive‐spray systems for gas‐phase production of metal sulfides are potential materials for next‐generation technologies. These flame‐synthesized sulfides (doped, functionalized, and heterogeneously mixed derivatives) hold significant potential as photocatalysts for water splitting. The knowledge acquired from nonaqueous precursor‐solvent and high‐temperature aerosol chemistries, optimal process parameters are established to generate In2‐(4/3)xSnxS3, solid‐solutions. The thermally driven reducing gas‐phase reactions are controlled through fuel/oxygen ratio. Particles characterizations (X‐ray diffraction, transmission electron microscopy (TEM) and imaging) revealed structural stability and crystallinity. The In2‐(4/3)xSnxS3, at higher Sn doping had enhanced photoexcitation. Donor‐acceptor levels within the material facilitated electron‐hole pair trapping, crucial for redox reactions. With suitable band gap energies for water oxidation (1.91.1 eV) closely matched flat band potentials (4.384.67 eV) for redox reactions. The powder characterization showed 8% In2O3 in InSn0.75S3 after photocatalysis due to S‐degradation in the initial light “on/off cycles”. The pioneering process of employing oxygen‐deficient reducing flame enabled a series of photo‐catalytically active metal sulfide nanoparticles with work function energies in the range of 5.195.37 eV. This synthesis strategy holds the potential for impactful advancements in both industry and R&D, addressing the urgent need for new materials capable of inducing water oxidation under visible light.

Tailoring the luminescent and structural behaviors of pH-driven PPy/gC3N4/ZrO2 nanocomposite as an emissive layer material for OLED application

The polymeric nanocomposites were synthesized via an in-situ polymerization method, optimized through pH adjustment of zirconium oxide rather than concentration variation. X-ray powder diffraction analysis revealed phase transitions and average crystallite sizes ranging from approximately 6.52–9.16 nm, depending on the pH levels. Field Emission Scanning Electron Microscopy tool is used to analyze the granular nanosheets and nanoparticles like the microstructure of polypyrrole, graphitic carbon nitride and zirconium oxide at a high resolution. UV–visible spectroscopy determined an optical bandgap energy of about 2.44 eV, a refractive index of 2.17, and an optical conductivity of 3.15 × 1010 S/cm2. Forster resonance energy transfer between Zirconium dioxide and graphitic carbon nitride significantly enhanced photoluminescence emission. PL emission and color purity (45 %) of the optimized sample were examined using photoluminescence data. Electrical conductivity of ∼15.9 × 10−4 S/cm and dielectric constant of ∼14.77 were obtained from I to V and LCR meter measurements. These properties indicate that the pH-driven nanocomposite exhibits optimized electron-hole recombination rates, electrical conductivity, and suitable bandgap energy, making its potential impact as an emissive layer material for OLED applications.

In-situ construction of the novel In2S3/BiOIO3 heterojunction with boosted visible-light photodegradation performance for diverse persistent organic pollutants

Designing rational heterojunctions to achieve efficient separation and transmission of photoinduced charge carriers is one of the effective strategies to improve the activity of semiconductor photocatalysts. In this study, the novel In2S3/BiOIO3 binary heterojunctions were facilely synthesized at room temperature using a simple in-situ growth method. The physicochemical properties of the fabricated In2S3/BiOIO3 heterojunction catalyst were investigated using various techniques including XRD, FT-IR, BET, XPS, TEM, UV–vis DRS, PL, EIS, and PC analysis. The In2S3/BiOIO3 composite catalyst possesses suitable band position and bandgap energy and therefore is capable of degrading organic contaminants under visible light irradiation. The optimized composite catalyst with In2S3/BiOIO3 molar ratio of 0.5 (In2S3/BiOIO3-5) exhibited superior photocatalytic activity, achieving 98.6 % degradation rate for Rhodamine B (RhB), far surpassing the performance of the individual components. In addition, In2S3/BiOIO3-5 showed broad-spectrum photocatalytic activity in the decomposition of various organic pollutants including methyl orange (MO), methylene blue (MB), tetracycline (TC) and bisphenol A (BPA). The improved photocatalytic activity of the prepared composite catalysts can be ascribed to the formation of type-II heterojunction, which facilitates the separation and migration of e–/h+ pairs. The excellent photocatalytic properties and favorable structural stability make In2S3/BiOIO3-5 a viable material for degrading various persistent organic pollutants.

A cyclic trinuclear silver complex for photosynthesis of hydrogen peroxide.

The development of metal complexes for photosynthesis of hydrogen peroxide (H2O2) from pure water and oxygen using solar energy, especially in the absence of any additives (e.g., acid, co-catalysts, and sacrificial agents), is a worthwhile pursuit, yet still remains highly challenging. More importantly, the O2 evolution from the water oxidation reaction has been impeded by the classic bottleneck, the photon-flux-density problem of sunlight that could be attributed to rarefied solar radiation for a long time. Herein, we reported synthesis of boron dipyrromethene (BODIPY)-based cyclic trinuclear silver complexes (Ag-CTC), and they exhibited strong visible-light absorption ability, a suitable energy bandgap, excellent photochemical properties and efficient charge separation ability. The integration of BODIPY motifs as oxygen reduction reaction sites and silver ions as water oxidation reaction sites allows Ag-CTC to photosynthesize H2O2 either from pure water or from sea water in the absence of any additives with a high H2O2 production rate of 183.7 and 192.3 μM h-1, which is higher than that of other reported metal-based photocatalysts. The photocatalytic mechanism was systematically and ambiguously investigated by various experimental analyses and density functional theory (DFT) calculations. Our work represents an important breakthrough in developing a new Ag photocatalyst for the transformation of O2 into H2O2 and H2O into H2O2.

Critical review on the tetracycline degradation using photo-Fenton assisted g-C3N4-based photocatalysts: Modification strategies, reaction parameters, and degradation pathway

Over the years, the enormous use of tetracycline (TC) in pharmaceutical industries caused unwanted heap in the environment that led to the deterioration of human and ecological conditions. Therefore, the synergistic functioning of photo-Fenton and photocatalysis has been introduced which enables the regeneration of more •OH, •O2- species thereby enhancing the TC degradation performance of photocatalysts. Graphitic carbon nitride (g-C3N4) photocatalyst recently, gained massive consideration due to the suitable energy band gap, efficient preparation method, and physicochemical properties. However, due to some drawbacks, various modification strategies (doping, Z-Scheme, S-Scheme) have been adopted to perk up the degradation activity of bare g-C3N4. In the current review, we have provided insights into various modification strategies employed for g-C3N4 and reaction parameters for the effective remediation of tetracycline using photo-Fenton-assisted photocatalysis. The review further highlighted the potential of the integrated effect of g-C3N4-based photo-Fenton-assisted photocatalytic processes for achieving higher tetracycline removal efficiency followed by current challenges and future perspectives.

Electronic structures of lead-free Sn- or Ge-hybrid perovskite halides studied by first-principles calculation

Although CH3NH3PbI3-based perovskite compounds have excellent photovoltaic properties, the lead (Pb) is harmful to the environment, and Pb-free perovskite compounds are needed for next generation solar cells. Theoretical calculations could be one of the good methods to design the Pb-free compounds, and the first-principles calculation was used to predict the properties of the present proposed materials. The instability of organic molecules such as CH3NH3 is also a problem, and alkali elements such as cesium and rubidium could improve the stability. From these point of view effects of tin (Sn) or germanium (Ge) on the lead-free Cs- or Rb- -based perovskites including double perovskite structures were investigated by first-principles calculation in the present work. For the standard single perovskite structures, perovskites with chlorine have suitable band gap energies, higher electron mobilities, and photovoltaic performance compared with other iodine or bromine-based perovskites. For the double perovskite structures, bromine was found to be the suitable halogen, and Ge provided a higher electron density than Sn. The double perovskite structures also provided wider band gap energies and improved stability compared with the standard single perovskites, and the photovoltaic properties could be affected by hybridization of Sn/Ge or halogen ions.

Innovative complex perovskites for efficient hydrogen Evolution: A DFT-Based design strategy

Recently, hydrogen, a high-energy, non-polluting fuel, has attracted considerable attention. Perovskites are of great interest in the hydrogen energy field due to their attractive properties. Herein, first-time novel complex perovskites [K(Mg+2Nb+5)O3] were designed computationally. The DFT has been utilized to systematically examine structural, electronic, optical, elastic, and mechanical properties to explore their potential applications in producing solar-driven hydrogen. Complex compositions (varying Mg+2 and Nb+5 concentrations) likely to adopt cubic or pseudocubic (a≈b≈c) perovskite structures based on structural parameters and the Goldschmidt tolerance factor. Including Nb in the crystal structure plays a significant role in shaping the band gap energy. Formation enthalpies show that all compounds are dynamically stable and synthesizable. Absorption coefficients (∼105cm-1) and effective optical responsiveness in UV and visible range make them a potential candidate for light energy harvesting. The computed high dielectric constant, a declining trend in refractive index and reflectivity, and minimum energy loss characteristics are attractive and are suitable for optoelectronic applications. Mechanical elements, ductility, anisotropy, toughness, and crack resistance proposed that compounds are highly desirable for various applications. The proposed complex compositions could catalyze efficient hydrogen evolution reactions (HERs) due to their suitable bandgap energies, suitable absorption coefficients, and alignment of the band edges regarding the redox potential of water.

Electrodeposition of Cu2NiSnS4 absorber layer on FTO substrate for solar cell applications.

Potentiostatic and in situ electrochemical impedance spectroscopy (EIS) measurements were recorded to study the nucleation and growth mechanisms of electrodeposited Cu2NiSnS4 (CNTS) thin films from aqueous solution at different applied potentials. The electrodeposition process of Cu-Ni-Sn-S precursors were studied using cyclic voltammetry and chronoamperometry techniques. The nucleation and growth mechanism of these films was found to follow a three-dimensional progressive nucleation limited by diffusion-controlled growth. The nucleation mechanism is found to be influenced by the presence of S2O3 2-, which prompts the electrodeposition of S. In situ electrochemical impedance spectroscopy (EIS) investigates the electrodeposition behavior of CNTS precursors on the surface electrode. A capacitive behavior was observed at high frequencies, while the presence of Warburg diffusion was detected only for potentials less negative than -1.0 V vs. Ag/AgCl. The crystallographic structure, morphology, composition, and optical band gap of CNTS thin films was examined using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and UV-visible spectroscopy. Electrodeposition at -0.98 V vs. Ag/AgCl resulted in the formation of microsheets with a uniform morphology and homogeneous thickness of sulfurized CNTS film. This potential also proved to be optimal for achieving higher crystallinity, a pure phase, and a suitable band gap energy of approximately 1.6 eV.

A review of recent progress in solar fuel (Hydrogen) generation via photocatalytic water-splitting of cadmium sulfide (CdS) based photocatalyst

Globally, energy demand and environmental pollution affect the development of society. However, solar fuel generation via photocatalytic water-splitting became the most viable approach to address the global energy crisis. Cadmium sulfide is considered an ideal material for solar fuel (hydrogen) generation due to its promising, low-cost, suitable bandgap energy, desired band alignment, affordability, and simple preparation method. However, the solar-to-hydrogen (STH) conversion efficiency of CdS-based materials still needs to improve due to the high rate of photogenerated electron-hole pair recombination and photocorrosion, resulting in poor photocatalytic performance. Herein, an emerging approach for enhancing the stability and photocatalytic activity of CdS is discussed, including designing heterostructure, co-catalyst loading, etc., with a focus on charge carrier separation and transfer. Particular attention is given to the mechanism of the emerging approach that influences photocatalytic water-splitting. This review focuses on designing and developing of strategy for enhancing anti-photocorrosion CdS-based materials for solar fuel generation. Notably, the solar H2 production improvements achieved in studying the CdS material as the main photocatalyst, not a co-catalyst, were exclusively reviewed and discussed. The prospective, challenges and development in preparation for anti-photo corrosion CdS are discussed. Thus, this review would likely motivate researchers to broaden the applications for CdS-based materials in solar fuel (hydrogen) generation in an economical and eco-friendly approach.

Ab initio insight into the structural, vibrational, electronic, optical, magnetic, and thermal properties of lead-free perovskite Cs3Sb2Cl9 for solar cell application

In recent years, semiconducting lead (Pb) free perovskite materials have become more attractive materials due to their less toxicity. In this study, we have investigated structural, electronic, optical, magnetic, and thermal properties of Pb-free Cs3Sb2Cl9 perovskite material using density functional theory. We have calculated the Energy-Volume (E-V) curve to evaluate the structural stability. The estimated lattice parameters for the studied material are a = b = 7.818 Å and c = 9.436 Å. Electronic properties suggest that Cs3Sb2Cl9 is a semiconductor material with a suitable energy band gap (Eg = 3.214 eV) for solar cell applications. Optical properties like high absorption, high optical conductivity, and peak reflectivity value in the visible region suggest that Cs3Sb2Cl9 is the most promising material for photovoltaic applications. Furthermore, the dynamic vibrational stability has been investigated as a calculated phonon energy dispersion curve, which shows that Cs3Sb2Cl9 is a dynamically stable compound. The spin-polarized calculations show that the material as a whole and even at the elemental bands level has zero resultant magnetic moments. We have also calculated thermodynamic properties, including enthalpy, free energy, and entropy. Therefore, the calculated results suggest that Cs3Sb2Cl9 is a potential candidate for solar cell applications.

Effect of Different Amounts of Pt on Fe3O4−TiO2 for Photocatalytic H2 Production Under Solar Light

AbstractIn this study, Pt doped Fe3O4−TiO2 photocatalysts were synthesized in two steps; (i) Fe3O4−TiO2 (FT) was prepared by the complex‐assisted vapor thermal (VT) method, (ii) Pt was doped to Fe3O4−TiO2 (FT−Pt) by the polyol method. The effect of different amounts of Pt was investigated for photocatalytic hydrogen production. The absorption spectrum of FT with 5.0 % Pt exhibits a surface plasmon resonance (SPR) peak of ∼420 nm which corresponds to the band gap of 2.95 eV. The FT and Pt doped FT samples showed a less intense photoluminescence (PL) band than TiO2 (T) due to the lower e−/h+ recombination rate. By increasing % wt. Pt in the FT samples, PL intensity was decreased. Thus, Pt plays an essential role to hinder the recombination of e−/h+ pairs. Consequently, FT‐5.0 % Pt showed 144 μmol/g‐cat H2 production rate, just about 3.3 times higher than that of FT photocatalyst; due to the suitable band gap energy and the retarded e−/h+ recombination. Therefore, the synergistic effect of Pt and Fe3O4 is found to be beneficial to decrease the e−/h+ recombination rate thus the photocatalytic activity enhancement was achieved.

La4Ga2S8O3: A Rare-Earth Gallium Oxysulfide with Disulfide Ions.

Band gap engineering using multiple anions is an established approach to novel photocatalysts that exhibit suitable band gap energies for water splitting and high photocorrosion resistance. However, few studies have been conducted on photocatalysts with polyanions, including polychalcogenide ions. Here, we present a new quaternary gallium oxysulfide with disulfide pairs (S2)2-, La4Ga2S8O3, grown out of a KI molten salt. Single-crystal X-ray diffraction analysis revealed that the oxysulfide crystallizes in the orthorhombic space group Pbcn with lattice constants of a = 18.3330(6) Å, b = 13.0590(5) Å, and c = 5.9022(3) Å. In the crystal structure, the GaS4-based zigzag chains and OLa4-based fluorite-like strips are independently arranged in two dimensions, which alternately stack via the disulfide pairs along the third direction. The oxysulfide is a direct-type semiconductor with a band gap of 2.45 eV. First-principles calculations combined with X-ray photoemission spectroscopy measurements show that S 3p states derived from the disulfide pairs dominate the valence band maximum and conduction band minimum, and these band-edge positions are suitable for the oxidation and reduction of water. Our comprehensive study based on the electronic structure suggests that the disulfide pairs make La4Ga2S8O3 a potential photocatalyst for water splitting under visible-light irradiation.

Phosphorus doped carbon dots additive improves the performance of perovskite solar cells via defect passivation in MAPbI3 films

Perovskites have been widely investigated as absorber layer in photovoltaic technology owing to their excellent properties. For further enhancement of the power conversion efficiencies (PCEs) of MAPbI3 perovskite solar cells, here, we successfully synthesized phosphorus doped carbon dots (P-CQDs) by solvothermal method and investigated their effect as an additive on the perovskite film properties and photovoltaic performance. The results showed that electron-rich phosphorus can act as an excellent core unit in perovskite absorber layer to passivate defects at the surface for improved the crystallization and charge transport properties. Thanks to passivation effect of P-CQDs on perovskite films, as well as the suitable energy band gap values and optical properties of MAPbI3 layer, the device prepared with the addition of 5 vol% of P-CQDs achieved a champion PCE of 13.12% with a high fill factor (FF) of 73.44%, higher than the PCE of 10.71% with a FF of 58.81% for control device.

Enhanced photoresponse of InxMo1-xS2 (X = 0.05 and 0.1) nanosheets for PEC type photodetector

Transition metal chalcogenides (TMDCs) have great potential in the field of solid state photodetectors and photoelectrochemical (PEC) type photodetector owing to high carrier mobility and suitable energy band gap. Two dimensional MoS2, most intensively investigated member of TMDCs, has shown excellent photoresponsivity in the visible range owing to excitonic transition and suitable electronic structure. Herein, we demonstrate the PEC photodetector based on InxMo1-xS2 nanosheets. High yield liquid phase exfoliation techniques have been employed for the synthesis of InxMo1-xS2 nanosheets. InxMo1-xS2 nanosheets have hexagonal lattice structure with highly crystalline behavior and X-ray diffraction confirms the doping of indium in 2H–MoS2. PEC type detectors show 582 μA/W and 107 μA/W photoresponsivity for In0.05Mo0.95S2 and In0.1Mo0.9S2 nanosheets by optimized concentration of indium. Present investigation advocates the significant development in the field of opto-electronics and photoelectrochemical cells for generation clean energy.

Photocatalytic hydrogen production using graphitic carbon nitride (GCN): A precise review

The positive feedback mechanism resulting from the exponentially increasing population leads to high energy demands, additional resource utilization, and debilitating nature, making the earth an unsustainable habitat for living. The resulting increase in global temperature, also leads to an increased carbon footprint, creating a chain of events called loop functioning or positive feedback chain. The renewable energy-driven water splitting and generation of hydrogen, which is further used as a clean fuel, serves as a sustainable route for satisfying the over enhanced energy demand and also helps in reducing the global carbon footprint by minimizing the resulting emission. The recent advancement in the photo catalytic systems, especially introduction of advance photocatalysts in the last decade, serves the path more enviably. The photocatalysts involved in the process of hydrogen production and using renewable energy as a driving force, especially solar energy, should remain unaltered. The desired changes in the catalytic activity, separation and conveying of charges at its surface are further catalysed by the solar energy. With technological advancement, novel and cost-effective hydrogen production mechanisms are evolving. This search for a cheaper, effective and sustainable photocatalyst material, which effectively splits the water molecules into desirable hydrogen isotopes is the need of the hour to sustain the ever growing energy demands. And in all this pursuit, a metal-free, suitable bandgap energy, cost-effective and 2D structured compound known as graphitic carbon nitride (GCN or g-C3N4) serves as a potential contender by effective splitting and efficient production of hydrogen. But GCN, even having so much potential, undergoes some challenges such as high density of defects, required surface area and desirable stability that restrict its photocatalytic activity and resulting water splitting efficiency. The present review addresses the latest trends in the composition variabilities in GCN that helps in increased splitting efficiency, doping with metallic particles, heterojunction formation in semiconductors, pore size-perviousity changes, modulation of the bandgap, control of defects and alteration in the surface area. This review also highlights the peak development and changes in the design and morphology of GCN under larger surface area performance and corresponding advancements in hydrogen production. Although not all renewable energy sources are considered; in this review, the photocatalytic production of hydrogen using the solar energy-driven channel is the primary highlight. Further, the concluding portion of this review helps the readers/scientific community to get a clear idea about photocatalytic hydrogen production and its derived routes, which also serve as an inoculum for future studies in the same domain.

NiO Modified CN Film As Photoanodes for Photoelectrochemical Water Oxidation

The utilization of solar energy, by far the most promising renewable energy resource, remains one of the hottest topics in the 21st century. Metal-free carbon nitride (CN) material emerged as a promising water splitting photocatalyst in 2009 due to its appropriate visible light absorption, suitable optical band gap energy (2.7 eV), and facile synthesis. Though CN is one of the leading materials for solar energy conversion, this material is limited by light absorption, rapid charge recombination, and low charge carrier mobility. Metal oxide are thus investigated for counterbalancing CN’s inherent drawbacks. Interfacial CN/metal oxide heterostructures facilitate charge transportation, resulting in improved sunlight-driven water splitting process. In this work, low-cost NiO transition-metal oxide material was applied to speed up the sluggish kinetics of the oxygen evolution reaction (OER). Typically, CN modification is achieved by traditional hydrothermal approach, while its disadvantages such as uneven coating particle size and heterogenous distribution are becoming increasingly apparent. Aiming at a conformal morphology, atomic layer deposition (ALD) is developed as the state-of-the-art technique. It has boosted the depositing accuracy by achieving precisely depositing thickness and extremely homogenous surface. In our process, a uniform CN film was deposited on FTO substrates using a dipping-drying technique with a hot saturated thiourea aqueous solution followed by a thermal treatment. Then plasma-enhanced atomic layer deposition (PEALD) was used to modify the CN film with a thin layer of NiO. PEALD controls the NiO modification on a fine-scale, allowing to with deposit a nanoscale NiO layer on the CN surface while exposing adequate CN photoreactive sites. According to our results, the modified NiO/CN heterostructure has the potential to improve photoelectrochemical water oxidation as a photoanode in alkaline solution. From the morphology side, the NiO loaded flake-like CN creates relatively high specific area for OER. Then we investigated the photo-process kinetic using a series of optical and spectroelectrochemcial techniques. Optical absorption is enhanced, showing stronger visible light absorption up to 700 nm. Fast charge separation is suggested in photoluminescence (PL) characterization. Superior (photo)electrochemical (PEC) activity is foreseen through PEC and EC measurements. To conclude, this is the first time we succeed to modify the CN film with the ALD technique for solar-driven water oxidation, and has the highly possibility of reaching the photo(electro)chemical performance new level.

First-principles prediction of stable Janus BiSbC3 monolayer with tunable electronic and optical properties under strain

In this study, first-principles calculations were used to study the structural, electronic and optical properties of a novel stable Janus BiSbC3 monolayer under varied biaxial strain levels. The structural and phonon dispersion calculations show that the novel Janus BiSbC3 is thermodynamically stable. At the equilibrium state, our results show that the Janus BiSbC3 monolayer is a direct semiconductor with a suitable energy band gap of 0.86 eV, which is converted to an indirect band gap with a biaxial tensile strain of +4%. It is worth noting that compressions strain of −8% causes a semiconductor-metal phase transition. The optical properties such as dielectric constant, reflectivity, extinction coefficient and absorption coefficient improved under biaxial strain with an enhanced absorption coefficient in the infrared and visible regions. Interestingly, a high absorption coefficient of 15.30×106cm−1 in the visible region under biaxial strain was predicted. Our calculations show that the novel Janus BiSbC3 monolayer has potential applications in optoelectronics and optical devices.

Synergistic effects of the hybridization between boron-doped carbon quantum dots and n/n-type g-C3N4 homojunction for boosted visible-light photocatalytic activity.

Dye wastewater has raised a prevalent environmental concern due to its ability to prevent the penetration of sunlight through water, thereby causing a disruption to the aquatic ecosystem. Carbon quantum dots (CQDs) are particularly sought after for their highly tailorable photoelectrochemical and optical properties. Simultaneously, graphitic carbon nitride (g-C3N4) has gained widespread attention due to its suitable band gap energy as well as excellent chemical and thermal stabilities. Herein, a novel boron-doped CQD (BCQD)-hybridized g-C3N4 homojunction (CN) nanocomposite was fabricated via a facile hydrothermal route. The optimal photocatalyst sample, 1-BCQD/CN (with a 1:3 mass ratio of boron to CQD) accomplished a Rhodamine B (RhB, 10mg/L) degradation efficiency of 96.8% within 4h under an 18W LED light irradiation. The kinetic rate constant of 1.39 × 10-2min-1 achieved by the optimum sample was found to be 3.6- and 2.8-folds higher than that of pristine CN and un-doped CQD/CN, respectively. The surface morphology, crystalline structure, chemical composition and optical properties of photocatalyst samples were characterized via TEM, FESEM-EDX, XRD, FTIR, UV-Vis DRS and FL spectrometer. Based on the scavenging tests, it was revealed that the photogenerated holes (h+), superoxide anions (∙O2-) and hydroxyl radicals (∙OH) were the primary reactive species responsible for the photodegradation process. Overall, the highly efficient 1-BCQD/CN composite with excellent photocatalytic activity could provide a cost-effective and robust means to address the increasing concerns over global environmental pollution.

Influence of capping agents on morphology and photocatalytic response of ZnS nanostructures towards crystal violet degradation under UV and sunlight

The capped ZnS NPs (ZnSM1 and ZnSM2) found to be highly photoactive towards crystal violet (CV) dye. Nearly 93% and 88% degradation of CV was observed under UV and sunlight whereas very efficiency was shown by uncapped (ZnSUC) and standard ZnS nanostructures. • Different capping agents influenced morphology of ZnS NPs. • Successful passivation of functional groups over ZnS surface. • Surface defects made ZnSM1 and ZnSM2 quite photo-responsive under sunlight. • Efficient photostability determined by recyclability of ZnSM1 and ZnSM2. • 88% of CV degradation was observed using ZnSM1 under sunlight. Photo-responsive ZnS nanostructures (ZnSM1 and ZnSM2) were synthesized using 3-mercaptopropionic acid (MPA) and polyvinylpyrrolidone (PVP) capping agents respectively via reflux method. Capped photocatalysts hold unique optical properties such as absorption in visible region, multi band gap values and surface defects. Interestingly, structural analysis revealed that nanorods and nanospheres were formed with MPA and PVP whereas randomly arranged particles were formed without using any capping agent (ZnSUC). The successful passivation of COOH (1549 cm −1 and 1357 cm −1 ) in case of ZnSM1 whereas CH 2 (1284 cm −1 ) and C N stretching (1429 cm −1 ) for ZnSM2 was determined by FT-IR studies. Owing to effective charge separation, 1D structure, suitable band gap energies and higher surface area (252 m 2 g −1 ), ZnSM1 exhibited enhanced photocatalytic activity towards crystal violet degradation (CV, 93%) under UV light which was about two folds higher than standard ZnS. Under sunlight, uncapped ZnS nanoparticles (ZnSUC and std. ZnS) showed minor activity in comparison to capped ZnSM1 (88%) and ZnSM2 (77%). Moreover, 83% degradation of 2-nitrophenol (NP) was obtained using ZnSM1 without using any other reducing agent under solar irradiations. Thus, present work provides more insights to understand the outstanding activity of ZnS nanomaterials towards organic pollutants beyond UV region without metal deposition.

Emerging quantum dots spotlight on next-generation photovoltaics

Semiconducting quantum dots (QDs) received considerable attention for application in optoelectronic devices, such as solar cells, photodetectors and light-emitting diodes, due to their unique fundamental properties, including solution processability, size-dependent bandgap energies, high stability and low cost. Specifically, the suitable bandgap energy of QDs with strong light absorption in the visible and near-infrared regions makes them a kind of competitive photovoltaic materials toward next-generation photovoltaics. Herein, the advantages of emerging QDs, including infrared lead sulfide QDs and perovskite QDs, are highlighted for new generation photovoltaics, and the possible challenges and opportunities approaching high-performance solar cells are also proposed.