Trioctylphosphine Research Articles

Nickel Phosphide: The Effect of Phosphorus Content on the Activity and Stability toward Oxygen Evolution Reaction in Alkaline Medium.

In this work a systematic study of the effect of the metal to phosphorus ratio in Ni-P nanoparticles on their catalytic activity with respect to the OER is reported. To this end, nickel phosphide nanoparticles are synthesized through two different synthesis routes, one involving in-situ phosphidation and one involving ex-situ phosphidation. In-situ phosphidation is performed via two steps route in a one-pot synthesis, in which Ni nanoparticles are formed at 220 °C, but not isolated, and then transformed to phase-pure either Ni12P5 or Ni2P nanocrystallites. In the second synthesis method (ex-situ phosphidation), nickel nanoparticles with an excess amount of trioctylphosphine (TOP) as a capping agent are synthesized and separated from the solution, then subsequently annealed in three different atmospheres, leading to the formation of three types of NixPy viz. [NixPy-H2/Ar], [NixPy-Ar], and [NixPy-air]. [NixPy-air] nanoparticles shows the best electrocatalytic activity among the annealed nanoparticles in Ar and H2/Ar but lower than Ni12P5 nanoparticles. However, [NixPy-air] shows very high stability in comparison with other synthesized nanoparticles. Moreover, the effect of the adventitious and spiked Fe in the electrolyte is studied on the electrocatalytic activity of all synthesized nanoparticles.

Synthesis of Amorphous and Various Phase-Pure Nanoparticles of Nickel Phosphide with Uniform Sizes via a Trioctylphosphine-Mediated Pathway.

Nickel phosphides are of particular interest because they are highly active and stable catalysts for petroleum/biorefinery and hydrogen production. Despite their significant catalytic potential, synthesizing various phase-pure nickel phosphide nanoparticles of uniform size remains a challenge. In this work, we develop a robust trioctylphosphine (TOP)-mediated route to make highly uniform phase-pure Ni12P5, Ni2P, and Ni5P4 nanoparticles. The synthetic route forms amorphous Ni70P30 nanoparticle intermediates. The reactions can be stopped at the amorphous stage when amorphous particles are desired. The amount of P incorporation can be controlled by varying the ratio of TOP to Ni(II). The mechanism for composition control involves the competition of the kinetics of two processes: the addition of the reduced Ni and the incorporation of P into Ni. Uniform Ni70P30 amorphous nanoparticles can be generated at a high TOP-to-Ni(II) ratio, where the P incorporation kinetics is made to dominate. Ni70P30 can later be transformed into phase-pure Ni12P5, Ni2P, and Ni5P4 nanocrystals of uniform size. The transformation can be controlled precisely by modulating the temperature. A UV-vis study coupled with theoretical modeling reveals Ni(0)-TOPx complexes along the synthetic path. This approach may be expanded to create other metal compounds, potentially enabling the synthesis of uniform nanoparticles of a greater variety.

TOPO-decanoic acid based DES – Structural insights using DFT, physico-chemical investigations and extraction efficiency of DES diluted with chloroform

Deep eutectic solvents (DESs) are recently regarded as evolving candidates in the field of separation science in order to achieve sustainability. In the present work, hydrophobic TOPO-Decanoic acid DES has been synthesized and scrutinized by FTIR and 1HNMR studies. The structures of TOPO (Tri-octyl phosphine oxide), decanoic acid, chloroform, DES and DES + chloroform have been optimized employing B3LYP functional using DFT-D3 of Grimme’s method. The HOMO-LUMO (Eg) energy gap, bond lengths, mulliken charges,dipole moment and interaction energy has been evaluated using DFT. The geometry optimization provides the bond parameters which explain about the existence of non-bonded interactions. DES and DES + chloroform show more reactiveness as compared to its constituents evident from the chemical potential value. Physico-chemical properties such as density, volumetric (V), dielectric constant (ε), refractive index (nD) and ultrasonic velocity (U) of the hydrophobic TOPO-Decanoic acid DES diluted with polar cosolvent chloroform have been determined over a wide range of mole fraction of DES at 298.15 K. The excess properties such as VE, εE, nDE and UE have been calculated to predict the type of inter-molecular interaction existing within the components of the DES diluted chloroform mixture. Different mixing rules have been used to estimate properties such as dielectric permittivity, refractive index and ultrasonic velocity. Various acoustic parameters such as Z, βs, and (Lf)mix of binary mixtures are evaluated to predict about the presence of inter molecular interactions within the mixture components. The prepared hydrophobic eutectic mixture in chloroform has been further used for extraction of Y (III) and Eu (III). The solvent extraction of Eu (III) showed better performance as compared to that of Y (III).

Chalcogen-Based Precursors for Transition Metal (Co, Ni) Phosphides: (Di)chalcogenide-to-Phosphide Transformation via Chemical Extraction of Chalcogenides.

The chemical properties of polymorphic compounds are highly dependent on their stoichiometry and atomic arrangements, making certain phases technologically more important. Selective development of these phases is challenging. This study introduces a method where chalcogenide atoms from metal chalcogenides are chemically extracted by trioctylphosphine (TOP) and substituted with phosphide. Using this approach, dithiocarbamate/xanthate complexes of cobalt and nickel were employed for the selective synthesis of pure metal sulfides or phosphides. Optimization yielded either sulfur-deficient phases (Ni3S2, Co9S8) or a complete transformation to phosphides (Ni2P, CoP). Likewise, for the first time, selenobenzoate complexes of Ni and Co were used for the synthesis of transition metal diselenides (NiSe2, CoSe2), which could then be converted to metal phosphides (Ni2P, Co2P). The synthesis used solution-phase thermal decomposition with various precursors, surfactants, and temperatures. With TOP, different phases of metal chalcogenides, metal phosphides, and mixed metal phosphide nanomaterials (NiS, Ni3S2, Co9S8, NiSe2, CoSe2, Ni2P, Ni5P4, Co2P, CoP, and Ni2-xCoxP) were obtained by varying reaction conditions. The formation mechanism of nickel and cobalt phosphide nanoparticles from precursors is proposed, demonstrating that presynthesized metal chalcogenides can be transformed into phosphides, opening a new research avenue for dimensionally controlled metal chalcogenides as templates for metal phosphides.

The Narrow Synthetic Window for Highly Homogenous InP Quantum Dots toward Narrow Red Emission.

Low-toxicity InP-based quantum dots (QDs) exhibit potential for replacing Cd/Pb-containing QDs in the visible and near-infrared regions. Despite advancements, further improvement relies on synthesizing homogeneous InP QDs to achieve a high color purity. In a commonly employed two-step "seed-mediated" synthetic approach, we demonstrate the high sensitivity of InP seed sizes and size distribution to the quantities of trioctylphosphine (TOP) and tris(trimethylsilyl)phosphine [(TMS)3P], attributed to the process of "self-focusing of size distribution" and enhanced reactivity of In-oleate through coordination with TOP. During growth, the processes of size focusing and defocusing are modulated by the accumulation of oleic acid and TOP molecules, as well as the amount of (TMS)3P in the growth precursor, which may relate to the dissolution process of InP magic size clusters. Through precise control, the best valley/depth ratio of InP QDs was 0.52 at the first absorption peak at 571 nm, resulting in luminescence with a full width at half-maximum of 35 at 620 nm with an absolute photoluminescence quantum yield around 90% after heteroepitaxial growth with ZnSe and ZnS shells.

Amine‐Free Multi‐Faceted CsPbBr3 Nanocrystals for Complete Suppression of Long‐Lived Dark States

AbstractConventional amine‐capped perovskite nanocrystals (A‐PNCs) often show microscopic fluctuation (blinking) of photoluminescence (PL) between bright and near‐background (dark) states. The transient dark phases spanning milliseconds (ms) to several seconds timescale typically owe to the non‐radiative (NR) fate of charge carriers in crystal defect states, limiting the PNC's efficiency in optoelectronics. A PL study of a novel trioctylphosphine (TOP) capped rhombic cuboctahedron‐shaped amine‐free (AF) PNC is presented, demonstrating their fascinating nonblinking nature. While oleylamine‐capped hexahedron A‐PNCs as a reference system show long dark states, their population is completely suppressed in ≈90% of AF‐PNCs with random large‐amplitude PL fluctuations several times above the background. The PL trajectories of AF‐PNCs primarily comprise constant power spectral densities (PSDs) which are unprecedented and deviate from power‐law distribution as observed for A‐PNCs and most of the other blinking nanocrystals. Such signature of PSDs and frame‐by‐frame intensity jump analysis indicate a fast (<<ms) timescale charge‐carrier dynamics governing the PL emission of AF‐PNCs, likely involving short‐lived metastable states. Besides, long‐term stability and suppressed dark phases in ≈70% AF‐PNCs even 90 days after the synthesis is noteworthy. Altogether the study provides exceptional optical characteristics of photostable amine‐free PNCs which would be attractive to exploit in commercial display applications.

Synthesis of low-cost multi-element Pt-based alloy nanoparticles as catalysts for the oxygen reduction reaction.

Due to their high catalytic activity, stability, and economic benefits, Pt-based multi-element alloyed nanoparticles (NPs) are considered promising electrodes for oxygen reduction reactions. However, a synthesis method capable of controlling the reduction reaction of elements with different redox potentials to synthesize multimetallic alloy NPs is yet to be developed. In this study, monodisperse NiPtPd alloy NPs with varying compositions were synthesized using 1-heptanol as a reducing solvent. The selection of low-reducing noble metal precursors and complexing agents is done strategically to adjust the reduction time of metal ions. The spectroscopic results confirmed that olelylamine (OAm) preferentially coordinates with Pt ions, while trioctylphosphine (TOP) preferentially coordinates with Pd ions. Consequently, control of the elemental distribution within the particle is successfully achieved by adjusting the OAm/Pt and TOP/Pd molar ratios. Subsequently, Ni78Pt11Pd11 alloy NPs were designed, and their catalytic properties as electrodes in the oxygen reduction reaction (ORR) were examined. Despite a low noble metal content of 22%, the catalytic performance and stability were superior to and comparable to those of commercial Pt NPs, respectively.

Unconventional Synthesis of Metal (Ni, Co, Ag) Antimony Alloy Particles.

Bimetallic alloy materials attract interest owing to their properties and stability compared to pure metals, especially alloys with nanoscale dimensions. Metal antimony (MSb) alloys, specifically NiSb, are widely used for charge storage applications due to their high stability. Most synthetic approaches to form these materials require drastic conditions (e.g., high temperatures, potent reducing agents, and extended reaction times), limiting control over the final morphology. The other viable approach is a galvanic replacement that uses unstable materials as precursors. In this work, we present a new and facile method to prepare several MSb (M = Ni, Co, Ag) alloys with shape control by reacting Sb2S3 particles with a metal(M)-sulfide single source precursor in trioctylphosphine (TOP) under mild conditions. Furthermore, we explore the role of TOP as a reducing agent and demonstrate how both alloy constituents are crucial for mutual stabilization. Electrochemical studies are also performed on these NiSb particles, showing their ambipolar nature and allowing their utilization as the active ingredient in the demonstrated high-energy-density symmetric supercapacitor.

Highly efficient solid phase extraction of uranium with TOPO-menthol based eutectic solvent as stationary phase from acidic feed relevant to front-end applications

Novel methods of separation and purification are envisaged for natural uranium, containing 0.7% of fissile 235U, a precious resource that fuels nuclear power plants. The present study demonstrates Solid phase extraction (SPE) of uranium as a sustainable alternative to conventional liquid-liquid extraction, leading to minimisation of organic inventory and enhancement of ease of operation concerning usage of viscous eutectic solvent. Overcoming the issue of the low solubility of organophosphorus extractant tri-octyl phosphine oxide (TOPO) in a hydrocarbon diluent, the aqueous insoluble, non-ionic eutectic solvent could be prepared with biodegradable menthol having TOPO: menthol mole ratio of 1:2 (MT2), 1:3 (MT3) and 1:4 (MT4). Eutectic solvents were sorbed on radio chemically stable Chromosorb W resin as solid support (MTC2, MTC3, MTC4), with loading of 45% for MTC2 and 40% for both MTC3 and MTC4, confirmed by weight difference and thermogravimetry. Batch sorption studies of U(VI) from nitric acid medium revealed attainment of equilibrium at 60 min., following a pseudo-second-order rate equation, Langmuir adsorption isotherm and a static capacity of 19 mg g−1. The U(VI) uptake was found to increase with the increase in acid molarity indicating solvating mechanism of extraction (KD = 1240 ± 4, 4 M HNO3). Recyclability was established and stripping was effective with 0.5 M HNO3. Column operation was also successfully demonstrated (breakthrough capacity = 18.9 mg g−1). The U(VI) uptake of >98% was indicated for nitric acid-digested crude yellow cake matrices viz. sodium diuranate (SDU), magnesium diuranate (MDU) and heat-treated uranium peroxide (HTUP). For higher matrix content, near complete uranium uptake and suppression of extraction of representative impurities (Fe, Mn, Ni, Ce) was revealed indicating facile uranium separation and purification from matrices relevant to the front end of the nuclear fuel cycle.

Hot-injection synthesis of lead-free pseudo-alkali metal-based perovskite (TlSnX3) nanoparticles with tunable optical properties

The commercialization of organo-inorganic hybrid perovskite materials for optoelectronic applications is limited owing to the restriction of lead (Pb) usage in consumer electronics and the instability of organic cations in the perovskite structure. To address these challenges, we synthesize TlSnX3 (X = Cl, Br, and I) perovskite nanoparticles (NPs) with high crystallinity and uniformity using the hot-injection method. The optical properties of TlSnX3 NPs are fine-tuned by substituting the halide ions of TlSnX3. In addition, the oxidation of Sn in TlSnX3 NPs is effectively prevented by the strong reducing ligands such as dioleamide (DOA) and trioctylphosphine (TOP). Furthermore, TlSnX3 NPs-based perovskite solar cells (PSCs) are fabricated by a spin-coating method; they exhibited a high open-circuit voltage (∼1.4 V). These results demonstrate that TlSnX3 NPs can be an attractive candidate for solution-processable optoelectronic devices.

A Hydrophobic Deep Eutectic Solvent for Nuclear Fuel Cycle: Extraction of Actinides and Dissolution of Uranium Oxide

AbstractHydrophobic Deep Eutectic Solvents (DESs) have been attracting attention for metal ion extraction in solvent extraction process due to their favorable properties. A Trioctyl phosphine oxide (TOPO) and Thenoyl trifluoroacetone (HTTA) based hydrophobic DES was synthesized and characterized by FTIR and NMR spectroscopy. Actinide ions ( UO22+, Pu4+ and Am3+) and Eu3+ ion extraction was carried out using the DES which shows that it extracts these metal ions from aqueous nitric acid medium depending upon the molarity of nitric acid. At higher molarity of nitric acid (>5 M) the extraction becomes insignificant only for trivalent metal ions and open up the possibility to selectively strip trivalent metal ions from tetravalent and hexavalent ions. This DES was also used for dissolution of uranium oxide (UO3). The dissolution kinetics was studied and it was shown that oxide was dissolved within an hour at 80 °C. The maximum solubility of UO3 in DES was measured and found to be 130±5 mg/mL which is one of the highest reported solubility of UO3 in ILs and DES. The species of uranium which is formed in situ in DES was ascertained to be UO2(TTA)2.TOPO after dissolution of UO3 as supported by FTIR and NMR (1H and 31P) investigations.

Nanoplatelet Superlattices by Tin-Induced Transformation of FAPbI3 Nanocrystals.

The transition from 3D to 2D lead halide perovskites is traditionally led by the lattice incorporation of bulky organic cations. However, the transformation into a coveted 2D superlattice-like structure by cationic substitution at the Pb2+ site of 3D perovskite is unfamiliar. It is demonstrated that the gradual increment of [Sn2+ ] alters the FASnx Pb1- x I3 nanocrystals into the Ruddlesden-Popper-like nanoplatelets (NPLs), with surface-absorbed oleic acid (OA) and oleylamine (OAm) spacer ligand at 80°C (FA+ : formamidinium cation). These NPLs are stacked either by a perfect alignment to form the superlattice or by offsetting the NPL edges because of their lateral displacements. The phase transition occurs from the Sn/Pb ratio ≥0.011, with 0.64 wt% of Sn2+ species. At and above Sn/Pb = 0.022, the NPL superlattice stacks start to grow along [00l] with a repeating length of 4.37(3) nm, comprising the organic bilayer and the inorganic block having two octahedral layers (n = 2). Besides, a photoluminescence quantum yield of 98.4% is obtained with Sn/Pb = 0.011 (n ≥ 4), after surface passivation by trioctylphosphine (TOP).

A Review on Methods Available for Doping of High Energy Boron Particles Into Liquid Fuels

Metals and metalloids such as Fe, Al, Be, B, Li, Mg, Ti are used as high energy materials as they possess higher gravimetric and volumetric heating values than liquid fuels. Boron possesses the highest volumetric (136 kJ/cm3 ) heating values among most of the preferred metal particles however it is second highest in gravimetric (58 kJ/g) heating values. This review highlights different successful methods of introduction of boron/aluminum particles in liquid fuels maintaining its suspension stability by using various surfactants or functionalization by different groups of ligands. Commercially available boron powder (nominal diameter 800 nm) contains coarser and mixed-size boron particles that require long milling times or a two-step milling process before final sample preparation. Suspension stability of boron particles can be achieved by using various classes of surfactants or techniques involved in surface modification of particles. Surfactants that are commonly used are oleic acid, sorbitanoleate, tween80, etc. Sorbitan oleate is now a days gaining popularity as the best stabilizer for this type of fluid preparation. Another effective ligand (amphiphilic) that is Trioctyl phosphine oxide (TOPO) links with fuel with its hydrophobic chain (long carbon chain) and nanoparticles with its polar head group. Recently some studies employed the capping of nanoparticles with ionic liquids (ILs) like (1-methyl-4-amino-1,2,4-triazoliumdicyanamide ([MAT][DCA]),1-butyl-3-methylimidazoliumdicyanamide ([BMIM][DCA]) and Dicyanamide-based Dicationic Ionic Liquid (DCIL). Capping of nanoparticles with organic chemicals is commonly done by Silane, Polymethyl acrylic acid (PMAA), Octyloxy, etc. An attempt to coat the surface of boron with an energetic polymer (Glycidylazide polymer) was also made recently by many researchers. These methods are some of the best approaches to attain longtime stability of high energy particles dopedliquid fuel. After a thorough study of literature, the available techniques already tried and tested by different research groups have been presented.

Synthesis of new extractant P113 for cerium(IV) extraction and higher separation over thorium from bastnaesite

Cyanex923 (a mixture of four trialkyl (hexyl and octyl) phosphine oxides) has been extensively employed in the recovery of cerium (Ce(IV)) and fluorine (F), as well as the separation over thorium (Th(IV)) from bastnaesite. However, rigorous production conditions and involvement of highly toxic raw materials (PH3) have been critical problems to be solved during the synthesis of Cyanex923. Meanwhile, its extraction performance remains to be improved. Therefore, we attempted to adjust the feed ratio to increase the proportion of short carbon chain components, successfully synthesized a novel extractant (P113, a mixture of four trialkyl (hexyl and octyl) phosphine oxides) with contents of each component different from Cyanex923 using an environmentally benign method. The comparison with Cyanex923 revealed obvious improvement of P113 in terms of extraction efficiency, selectivity and saturation capacity. The extraction efficiency and saturation capacity of Ce(IV) were increased by 10% and 10 g L-1, respectively. Separation factor of Ce(IV)/Th(IV) was increased from 16 to 27 at 2 mol L-1 H2SO4. Furthermore, P113 presented excellent regenerability. The superiority of P113 was theoretically explored using the density functional theory (DFT) and polarizable continuum model (PCM), and the results indicated that THPO (trihexyl phosphine oxide) had lower extraction phase transfer energy than TOPO (trioctyl phosphine oxide) from aqueous phase to organic phase. The comprehensive evaluation of P113 demonstrated the feasibility employed in the recovery of Ce(IV)-F and the separation of Th(IV) from bastnaesite, which advanced industrial application of the novel extractant, and held significant value for the utilization of resources and environmental protection.

Group Extraction of the Rare-Earth Elements by Alkyl Phosphine Oxides of the Hexyl–Octyl Series

Samples of monoalkyl and mixed-alkyl phosphine oxides of the hexyl–octyl series were synthesized previously by the Grignard method. Here, the group extraction of rare-earth metals contained simultaneously in their nitrate solutions has been studied using then-synthesized alkyl phosphine oxides. Extraction isotherms for the recovery of the total of lanthanides, scandium, and thorium from nitrate solutions have been obtained. Trihexyl phosphine oxide (THPO) exhibits the highest efficiency under these conditions. Trioctyl phosphine oxide (TOPO) exhibits the best selectivity to heavy-group lanthanides, which makes it useful for the recovery of the heavy-group lanthanide fraction. In addition, scandium and thorium were extracted completely, which in turn indicates the usefulness of phosphine oxides for their extraction. The separation factors have been determined for the entire lanthanides series.

Surface engineering of colloidal quaternary chalcogenide Cu2ZnSnS4 nanocrystals: a potential low-cost photocatalyst for water remediation.

Colloidal route synthesis of quaternary compound CZTS (Cu2ZnSnS4) has been anticipated with an inimitable combination of coordinating ligands and solvents using the hot injection technique. CZTS is recognized as one of the worthiest materials for photo-voltaic/catalytic applications due to its exclusive properties (viz., non-toxic, economical, direct bandgap, high absorbance coefficient, etc.). This paper demonstrates the formation of crystalline, single-phased, monodispersed, and electrically passivated CZTS nanoparticles using a distinctive combination of ligands viz. oleic acid (OA)-trioctylphosphine (TOP) and butylamine (BA)-trioctylphosphine (TOP). Detailed optical, structural, and electrochemical studies were done for all CZTS nanoparticles, and the most efficient composition was found using ligands butylamine and TOP. CZTS nanocrystals were rendered hydrophilic via surface-ligand engineering, which was used for photocatalysis studies of organic pollutants. Malachite green (MG) and rhodamine 6G (Rh) for water remediation have great commercial prospects. The unique selling proposition of this work is the rapid synthesis time (~ 45min) of colloidal CZTS nanocrystals, cost-effective ligand-exchange process, and negligible material wastage (~ 200µl per 10ml of pollutant) during photocatalytic experiments.

Molecular Influences on the Quantification of Lewis Acidity with Phosphine Oxide Probes.

Gutmann-Beckett-type measurements with phosphine oxide probes can be used to estimate effective Lewis acidity with 31P nuclear magnetic resonance spectroscopy, but the influence of the molecular structure of a given probe on the quantification of Lewis acidity remains poorly documented in experimental work. Here, a quantitative comparison of triethyl (E), trioctyl (O), and triphenyl (P) phosphine oxides as molecular probes of Lewis acidity has been carried out via titration studies in MeCN with a test set of six mono- and divalent metal triflate salts. In comparison to E, the bulkier O displays a similar range of chemical shift values and binding affinities for the various test metal ions. Spectral linewidths and speciation properties vary for individual cation-to-probe ratios, however, confirming probe-specific properties that can impact the data quality. Importantly, P displays a consistently narrower dynamic range than both E and O, illustrating how electronic changes at phosphorus can influence the NMR response. Comparative parametrizations of the effective Lewis acidities of a broader range of metal ions, including the trivalent rare earth ions Y3+, Lu3+, and Sc3+ as well as the uranyl ion (UO22+), can be understood in light of these results, providing insight into the fundamental chemical processes underlying the useful approach of single-point measurements for quantification of effective Lewis acidity. Together with a study of counteranion effects reported here, these data clarify the diverse ensemble of factors that can influence the measurement of Lewis acid/base interactions.

Role of Trioctylphosphine in the Synthesis of Quantum Dots: A Modulator of Nucleation, Growth, and Solubility

Trioctylphosphine (TOP) is widely used in the synthetic process of colloidal quantum dots (QDs). However, its role has not been fully elucidated yet. Herein, the role of TOP was revealed by kinetic studies with spectroscopic methods. It was found that TOP suppressed the growth rate but increased the solubility; hence, it modulated QDs by controlling both. The extent of impact from TOP varied in the length of acids that was used in QD synthesis. In general, the impact from TOP to QDs synthesized by short acids was mainly the suppressing effect because shorter aliphatic acids had a higher diffusion rate, and they might suffer from TOP a lot. On the contrary, longer aliphatic acids diffused intrinsically slowly, so the reaction rate was rarely influenced by TOP, but the solubility was supposed to be considered at this time. This difference also led to the optimal amount of TOP used in the synthesis. These results pointed out that both the growth rate and solubility were time-dependent and should be considered to obtain high-quality QDs. In addition, the initial nucleation procedure was also seemingly suppressed by TOP. This work not only shed light on the underlying role of TOP and convinced the controllable synthesis of QDs but also provided a method to investigate the behavior of QD growth by considering several conditions synergistically and dynamically.

Synthesis and characterization of InP quantum dots for photovoltaics applications

In this article, InP quantum dots (QDs) are synthesized with a green methodology. The preparation of the InP QDs is demonstrated by varying the ratios of the precursors used such as InCl3 and trioctylphosphine (TOP). These QDs are fabricated through the application of TOP (as phosphorous source and reducing agent for the In salt) for forming indium and to develop the targeted InP QDs, which are characterized using HRTEM, XRD, PL, FTIR, UV–Vis, and time resolved spectroscopy. A rapid reaction time (~ 30 min) procedure in a single pot at a temperature of ~ 310 °C is developed. InP QDs with particle sizes varying from 4 to 6 nm have been measured with different concentrations of InCl3 and TOP. InP QDs yield reached 23%. Zincblende crystal structure is recognized for InP with high orientation plane of (220) as confirmed with XRD and confirmed with SAED. Solar cell devices are built by anchoring the InP QDs onto a TiO2 layer and measure the photovoltaic performance and spectral response of the device built on FTO/glass substrate. TiO2/InP QDs solar cell devices are fabricated with high fill factor of 0.86 and open circuit voltage value of 501 mV and overall efficiency of 0.48%.

Trioctylphosphine- and Octanethiol-Induced Photoluminescence Recovery of CdSe/ZnS Quantum Dots after Dilution–Quenching: Implications for Quantum Dot Films

In this work, CdSe/ZnS core/shell quantum dots (QDs) were synthesized. Dilution of the as-synthesized QDs would lead to instability with photoluminescence (PL) quenching. It was found that the addition of tertiary phosphine and alkylthiol could recover the PL intensity of diluted QDs and make these QDs stable. Specifically, the recovery efficiency of tertiary phosphine was stronger than that of alkylthiol. Trioctylphosphine (TOP) and octanethiol (OT) were chosen as the representative ligands, respectively. Isothermal titration calorimetry (ITC) demonstrated that interactions between both TOP/OT and QDs were exothermic and spontaneous. The interaction between TOP and QDs was mainly driven by van der Waals forces due to the branched structure. This interaction had a negative entropy change, while the interaction between OT and QDs had a positive entropy change. There were about ∼12 TOP molecules and ∼17 OT molecules bound to a QD particle. The binding constants of TOP/OT to QDs were 1.6 × 103 and 12.8 × 103 M–1, respectively. The reaction rate between TOP and QDs was fast, and the addition of OT could slow the reaction rate constant from 0.081 to 0.024 min–1. PL decay indicated that TOP and OT could increase the radiative recombination of excitons. Furthermore, both TOP and OT could greatly improve the brightness of the QD films, which was a prerequisite for the efficient improvement of quantum dot light-emitting diodes. This work explicitly investigated the dilution process of QDs, explored the methods for keeping diluted QDs stable and bright, and highlighted the importance of surface ligands.