Triethanolamine Solution Research Articles

Construction of S-scheme NiCoSe2/TiO2 heterojunction for efficient photocatalytic H2 evolution

In this work, TiO2 nanosheets and NiCoSe2 nanoparticles were synthesized via a hydrothermal method respectively, then NiCoSe2 was combined with TiO2 using a solvent evaporation strategy to form heterojunction for efficient photocatalytic H2 evolution. The investigation demonstrates that the H2 evolution rate of 5 %-NiCoSe2/TiO2 can reach up to 4976 μmol·g−1·h−1 in the sacrificial agent of 20 vol% triethanolamine (TEOA) solution under a 300 W Xe lamp irradiation, which is approximately 35.5 times higher than that of TiO2 (140 μmol·g−1·h−1). Besides, the composite exhibits excellent stability after undergoing five consecutive cycles. The prominent H2 evolution activity of this system can be attributed to the abundant redox active sites provided by the bimetallic selenides, as well as the enhanced light harvesting ability and photocurrent response, reduced electrochemical impedance especially the improved electron-hole (e--h+) pairs separation due to the formed S-scheme charge transfer route between TiO2 and NiCoSe2.This work demonstrates the promising application potential of bimetallic selenides in photocatalytic H2 evolution.

Multifunctional g-C3N4-PDI/MOF-545-NH2 photocatalyst for Enhanced CO2 reduction and aniline oxidation

The use of solar energy to convert CO2 into clean energy is one of the ideal strategies for achieving carbon neutrality. However, the rapid recombination of photogenerated electron holes, the complexity of the reduction products and the consumption of sacrificial materials severely limit its development and application. In this work, g-C3N4-PDI (CNP) and MOF-545-NH2 (MNH) were prepared by calcination and hydrothermal methods, respectively, and CNP/MNH photocatalysts were prepared by in situ growth of MNH on CNP surface. The photocatalytic CO2 conversion reaction of CNP/MNH in triethanolamine and aniline solutions was investigated. Experiments show that the prepared CNP/MNH catalyst has excellent photocatalytic performance. When triethanolamine was used as a sacrificial agent, the yield of CH4 reached 192.7 μmol·g−1·h−1 (selectivity 92.94 %). In particular, while the catalyst realizes the conversion of CO2 in the aniline solution, it is surprising to find that part of the CO2 is converted to ethanol. The catalyst’s photochemical properties, CO2 reduction pathway, and aniline oxidation products were characterized by XPS, UV–vis DRS, PL, electrochemistry, zeta potential, ESR, GC–MS and in-situ infrared spectroscopy. The results show that the modification of the catalyst and the formation of heterojunction not only increase the adsorption of CO2, but also accelerate the process of photogenerated electron migration, which plays an important role in the process of carbon dioxide conversion. This study provides a new perspective for the design of photocatalytic CO2 conversion catalysts, and also provides a feasible method for aniline wastewater treatment.

Enhanced Photocatalytic Activity of Surface‐Modified TiO2 with Bimetallic AuPd Nanoalloys for Hydrogen Generation

Herein, commercial titania (TiO2‐P25) is modified with mono‐ and bi‐metallic (Au, Pd, and AuPd) nanoparticles synthesized by chemical reduction method using NaBH4 as a strong reducing agent at room temperature. Bimetallic AuPd nanoalloys homogeneous in size and well dispersed on the TiO2 surface are obtained. The charge‐carrier dynamics, which is a key factor in photocatalysis, is studied by time‐resolved microwave conductivity. The results reveal that surface modification plays a crucial role in charge‐carrier separation, increasing the activity under UV–vis light irradiation. The bimetallic AuPd nanoalloys formation is confirmed by high‐angle annular dark field scanning transmission electron microscopy and corroborated by semiempirical molecular dynamics simulations (Gupta‐LAMMPS). The surface‐modified TiO2 with bimetallic AuPd nanoalloys exhibits higher photocatalytic activity compared to TiO2 modified with their monometallic counterparts. The experimental results are also supported by density functional theory and density functional tight binding calculations, which show that alloying AuPd with low Pd content presents significant synergetic effects for hydrogen generation under UV–vis light from aqueous triethanolamine solutions. Additionally, the AuPd/TiO2 photocatalysts are stable with cycling.

Nb2O5 and Nb based oxides as redox photocatalysts: Partial oxidation of 2-propanol and H2 generation by photoreforming

The structural and chemical properties of niobium oxide catalysts have been under scientific scrutiny for the last fifty years; however, their application in photocatalytic processes is very recent and still little studied. In this research, pristine Nb2O5 and its composites containing Ti, Ce, or Zr oxides have been used as photocatalysts in redox reactions such as 2-propanol oxidation in gas-solid regime and in aqueous phase triethanolamine photo-reforming to yield H2. All the materials were active in the oxidation of 2-propanol under simulated sunlight irradiation. The substrate was oxidised in the presence of all of the solids resulting in formation of propanone as the major intermediate product and CO2 as the final product. In liquid solid regime, the H2 production by UV-assisted photoreforming of aqueous solution of triethanolamine reached ca. 6 μmol h−1 g−1 for the best performing material, the bare Nb2O5, which increases up to 592 μmol h−1 g−1 in the presence of 1 % of Pt co-catalyst.

Controllable introducing C, N-defects and oxygen-doping on carbon nitride to tune electronic structure and boost photocatalytic hydrogen evolution

In this work, one-step pyrolysis of molten urea and formaldehyde was adopted to introduce O atom, C and N defects in polymeric carbon nitride (CN) for tuning its electronic structures. Results confirmed that the introduced C, N-defects and O dopant could increase the light absorption (440–640 nm) and suppressed the photogenerated charge recombination of CN. The calculated free energies for H* adsorption revealed that the intrinsic H2 evolution activity of C, N-deficient and O-doped CN increased. Accordingly, the optimal sample exhibited an excellent photocatalytic H2 evolution rate (HER) of 18.95 mmol g−1 h−1 in 10% triethanolamine solution under visible light irradiation (1% Pt as a cocatalyst), which was 6.7 times higher than that of traditional CN (2.83 mmol g−1 h−1). In addition, the HER and yield of benzaldehyde were 1.04 and 4.20 mmol g−1 h−1, respectively in 5% benzyl alcohol solution. This work provides a simple and effective strategy to tune the heptazine and electronic structure of CN for large increasing its photocatalytic activity.

Scanning electrochemical probe microscopy: towards the characterization of micro- and nanostructured photocatalytic materials.

Platinum-black (Pt-B) has been demonstrated to be an excellent electrocatalytic material for the electrochemical oxidation of hydrogen peroxide (H2O2). As Pt-B films can be deposited electrochemically, micro- and nano-sized conductive transducers can be modified with Pt-B. Here, we present the potential of Pt-B micro- and sub-micro-sized sensors for the detection and quantification of hydrogen (H2) in solution. Using these microsensors, no sampling step for H2 determination is required and e.g., in photocatalysis, the onset of H2 evolution can be monitored in situ. We present Pt-B-based H2 micro- and sub-micro-sized sensors based on different electrochemical transducers such as microelectrodes and atomic force microscopy (AFM)-scanning electrochemical microscopy (SECM) probes, which enable local measurements e.g., at heterogenized photocatalytically active samples. The microsensors are characterized in terms of limits of detection (LOD), which ranges from 4.0 μM to 30 μM depending on the size of the sensors and the experimental conditions such as type of electrolyte and pH. The sensors were tested for the in situ H2 evolution by light-driven water-splitting, i.e., using ascorbic acid or triethanolamine solutions, showing a wide linear concentration range, good reproducibility, and high sensitivity. Proof-of-principle experiments using Pt-B-modified cantilever-based sensors were performed using a model sample platinum substrate to map the electrochemical H2 evolution along with the topography using AFM-SECM.

Construction of Z-scheme heterojunction interfacial charge transfer pathways in ZnIn2S4@NENU-5 for photocatalytic hydrogen evolution.

Utilizing the design of heterojunction structures formed between photocatalysts to enhance photoelectrochemical performance represents an effective strategy for improving the efficiency of photocatalytic hydrogen production. In this work, a straightforward one-step solvothermal method was employed to embed NENU-5 nano-octahedra within ZnIn2S4 nanoflowers, forming ZnIn2S4@NENU-5 heterostructures. Hydrogen production tests conducted over 5 h revealed a hydrogen evolution activity of 5282.14 μmol g-1 h-1 in triethanolamine (TEOA) solution at pH = 9, which is 4.9 times and 264 times higher than that of pure ZnIn2S4 and NENU-5, respectively. The significant enhancement in the photocatalytic performance indicates that the constructed Z-scheme heterojunction increases the active sites on the catalyst surface and plays a crucial role in photocarrier transfer. Furthermore, the formation of the Z-scheme heterojunction is confirmed through Mott-Schottky (M-S) analysis, ultraviolet photoelectron spectroscopy (UPS), and valence band X-ray photoelectron spectroscopy (VB-XPS). The effective charge transfer at the ZnIn2S4@NENU-5 heterojunction interface is validated based on X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) analysis, and density functional theory (DFT) calculations. In summary, this work offers an effective approach to designing novel heterojunction photocatalysts by combining MOF materials with bimetallic sulfides, thereby promoting the efficiency of photocatalytic hydrogen production.

Effects of CO2-absorbed triethanolamine solutions on strength development of cement mortars and the mechanism: Synergism of cement hydration and carbonation

In this study, the impacts of CO2-absorbed triethanolamine solutions (TEA-CO2) on the mechanical property, phase composition and micro-structure of cement mortars were investigated. The results showed that TEA-CO2 addition increased the 1d, 3d, and 28d compressive strength by 47%, 19%, and 4%, respectively, which suggests a synergistic effect of triethanolamine and absorbed CO2 on strength development of cement mortars. The enhancement is due to TEA-CO2 accelerates hydration of aluminate and silicate phases in early age. TEA-CO2 facilitated CaCO3 formation to increase cement hydration degree and modify the pore structures. However, the hydration of silicate phases was delayed slightly by TEA-CO2 at 28d. The above results provide theoretical support for further utilization of CO2 in cementitious materials.

Electrostatic loading and photoredox-accelerated release of antibiotics from oligoviologen-crosslinked hydrogels using red light

Hydrogel drug delivery is the subject of an ever-expanding industry where delivery occurs by numerous methods, many of them passive in nature. On-command, stimuli-driven release, particularly using light to initiate spatiotemporal, controlled release of cargo is a more attractive approach than passive release methods. Here, we report a novel method for electrostatically loading negatively charged dye and antibiotic cargo in biocompatible, oligoviologen-crosslinked hydrogels equipped with an integrated Aza-boron-dipyrromethene (Aza-BODIPY) photocatalyst. Following loading, the release of the electrostatically bound cargos can be accelerated upon irradiation with red light (660 nm) through a photoinduced electron transfer (PET) process that reduced the oligoviologen subunits. A free radical polymerization method was used to fabricate the hydrogels with a hydroxyethyl acrylate backbone, co-crosslinked by a viologen hexamer (6V-St•12Cl) and Aza-BODIPY derivative. Irradiation of the Aza-BODIPY photocatalyst led to a reduction of the viologen subunits to their monoradical cation oxidation state via PET. The photocatalyst was regenerated in situ in a triethanolamine (TEOA) solution, which served as a sacrificial reductant. Negatively charged dye (i.e., methyl orange, MO) was electrostatically loaded into the hydrogel through counteranion metathesis, followed by irradiation with red light to release the dye as the subunits of the viologen crosslinker lost positive charges (i.e., V2+ to V●+). Controlled release of the dye was tracked by UV/Vis absorption spectroscopy, yielding up to 74 % of cargo released in 75 h. Negatively charged antibiotic cargo (i.e., nalidixic acid) was then electrostatically loaded into and released from hydrogels by the same method. Controlled release of the drug was tracked by agar diffusion and liquid broth microdilution antibacterial susceptibility assays, where bacterial growth inhibition was recorded, confirming the same release trends observed for the dye cargo.

A NEW STRATEGY FOR THE SYNTHESIS OF HIGHLY ACTIVE CATALYSTS BASED ON <i>g-</i>C<sub>3</sub>N<sub>4</sub> FOR THE PHOTOCATALYTIC PRODUCTION OF HYDROGEN UNDER VISIBLE LIGHT

In this work, materials based on graphite-like carbon nitride were synthesized by thermal treatment of a mixture of melamine and urea and the effect of synthesis conditions on the photocatalytic activity of the samples was studied. As a cocatalyst, platinum (1 wt. %) was deposited on the surface of the synthesized g‑C3N4 samples. The photocatalysts were characterized by X-ray phase analysis, diffuse reflectance UV-vis spectro-scopy in the UV and visible range, and low-temperature nitrogen adsorption. Photocatalytic activity was determined in the reaction of hydrogen evolution from an aqueous solution of triethanolamine (10 vol. %) under visible light irradiation (λ = 425 nm). The optimal conditions for the synthesis of the photocatalyst 1% Pt/g-C3N4, obtained by calcination of a mixture of melamine and urea (1 : 3), were found, using which the rate of H2 evolution was 5.0 mmol g–1 h–1 with an apparent quantum efficiency of 2.5%. The developed synthetic approach makes it possible to obtain highly active catalysts due to the formation of an intermediate supramolecular melamine-cyanuric acid complex during the synthesis, which, upon further heating, turns into g-C3N4, which is characterized by a high specific surface area exceeding 100 m2 g–1.

Carbon dioxide capture with aqueous calcium carbide residual solution for calcium carbonate synthesis and its use as an epoxy resin filler

Calcium carbide residue (CCR) is a waste obtained from the production of acetylene gas by the hydration reaction of calcium carbide. This residue is generated in large quantities annually and requires appropriate disposal. The main composition of the residue is calcium hydroxide (Ca(OH)2). Ca(OH)2 can react with CO2 gas and form CaCO3 particles. This process is well known but not very attractive since Ca(OH)2 is obtained from limestone using an energy-intensive thermal conversion process. This paper examined the synthesis of CaCO3 from CCR solutions by capturing CO2 with the aid of triethanolamine (TEA) solutions at doses of 0, 5, 10 and 20% w/w. The precipitated CaCO3 was characterized, and the application of CaCO3 as a filler in epoxy resin was tested. The results showed that the precipitated CaCO3 was mainly calcite, with a 76.6% yield. Cubic calcite was primarily obtained in TEA solutions, whereas small and agglomerated spherical vaterite and cubic calcite particles were formed in non-TEA solutions. The CaCO3-filled epoxy composites showed higher compressive strength than the neat resin. However, the transparency of specimen plates was reduced. These results can serve as guidelines for the application of CCR slurry filtrate obtained from the sedimentation ponds of acetylene plants and help to reduce the amount of wastewater that needs to be treated. CO2 gas from industrial flue gas combined with TEA solution could be applied to precipitate CaCO3 for carbon-neutral manufacturing.

The yielding behavior of aqueous solutions of Carbopol and triethanolamine and its prediction considering the fractal nature of the formed aggregates

The yielding behavior of aqueous solutions of Carbopol and triethanolamine and its prediction considering the fractal nature of the formed aggregates

Carbon dioxide absorption by Ammonia-promoted aqueous triethanolamine solution in a packed bed

Carbon dioxide absorption by Ammonia-promoted aqueous triethanolamine solution in a packed bed

Novel Two-Stage Method of Preparing Graphitic Carbon Nitride Doped by Chlorine for Photocatalytic Hydrogen Evolution and Photocurrent Generation

In this work graphitic carbon nitride doped by chlorine was prepared by a two-stage technique at first. At the first stage melamine was hydrothermally treated with glucose, at the second stage the mixture of as-prepared melamine with ammonium chloride was calcined. The obtained samples were investigated by the set of methods: X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy, photoelectrochemical methods. All prepared photocatalysts was tested in the reaction of photocatalytic hydrogen production from basic solutions of triethanolamine. It was shown that the highest values of the catalytic activity and short-circuit current density were obtained over the photocatalyst preparing by calcination of the mixture containing 30% ammonium chloride and 70% melamine. The highest value of the catalytic activity was 1332 μmol h–1 g–1 and was more than the catalytic activity of carbon nitride preparing by the melamine calcination without another treatment in 22 times.

In Situ X-ray Photoelectron Spectroscopy (XPS) Demonstrated Graphdiyne (g-CnH2n–2) Based GDY-CuI/NiV-LDH Double S-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution

As a new two-dimensional layered carbon material, graphdiyne (GDY) is widely used in various fields because of its excellent electrical conductivity and tunable electronic structure. In this work, graphdiyne, a two-dimensional layered carbon material, is prepared by an alkyl terminal coupling method using Cu+ as a catalyst. Nickel–vanadium hydro calcite (NiV-LDH) is anchored on the surface of GDY-CuI bya solvothermal method to form a double S-scheme heterojunction photocatalytic hydrogen precipitation system. The double S-scheme heterojunction suppressed the electron–hole recombination in the composite catalyst, which greatly improved the transfer rate of photogenerated carriers. Meanwhile, a tight and unique interface is formed in the composite, which not only accelerates the separation and transfer of electron holes but also improves the catalytic stability of the composite. H2 (73.65 μmol) is produced in 5 h in triethanolamine solution, which is 4.1 and 3.7 times higher than those with NiV-LDH and NiV-LDH/CuI. Twenty-five hour cycling experiments demonstrated the catalytic stability of the materials. This work provides an effective strategy for the rational construction and application of graphdiyne group hetero structures in the field of photocatalytic hydrogen evolution.

Effect of Ethane on the Solubility of CO2 in Aqueous Triethanolamine Solutions

Effect of Ethane on the Solubility of CO2 in Aqueous Triethanolamine Solutions

A direct Z-scheme NiCo2O4/ZnIn2S4 heterojunction for highly efficient visible-light-driven H2 evolution.

Exploiting efficient and stable photocatalysts is the primary goal of photocatalytic water splitting for H2 production. In this work, a sea urchin-like bimetallic NiCo2O4-decorated ZnIn2S4 heterojunction was fabricated via a solvent evaporation method. Investigation shows that the introduction NiCo2O4 can expand the UV-vis absorption range, enhance the absorption intensity, promote the charge separation, decrease the charge transfer resistance, induce more active sites, and decrease the H2 evolution overpotential of the composite. Besides, the charge transfer between NiCo2O4 and ZnIn2S4 follows a Z-scheme route based on the ˙OH radical capture experiments; this can preserve the strong oxidation-reduction reaction ability of photogenerated electrons and holes, leading to a faster H2 evolution rate, which reaches 17.28 mmol g-1 h-1 over the 4.8%-NiCo2O4/ZnIn2S4 composite under 300 W Xe lamp irradiation in 20 vol% triethanolamine (TEOA) solution and is 3.0 times higher than that of ZnIn2S4. In addition, NiCo2O4/ZnIn2S4 also has excellent stability during 5 consecutive cycles. This work provides an effective method for constructing a highly effective Z-scheme heterojunction system for photocatalytic H2 production.

C3N4/reduced graphene oxide photocatalysts loaded with Ag or Ag/Pt for H2 evolution from aqueous solution of triethanolamine

Composites of C3N4/reduced graphene oxide have been used as photocatalysts for triethanolamine photo-reforming with H2 generation in aqueous solution. The rate of H2 production over the Ag loaded best performing photocatalyst reached 525 μmol·h−1·g−1 which increases to ca. 88,000 μmol·h−1·g−1 in the presence also of 1% of Pt. The apparent quantum efficiency (AQE) of the optimal material was ca. 9% by using both visible LED or natural sunlight irradiation.

Ca1-xSrxGa2O4 (0.2≤x≤0.7): A novel photocatalyst with special stability for H2 production

Herein, we reported a series of semiconductors as novel photocatalysts under ultraviolet light. The Ca1-xSrxGa2O4 (0.2 ≤ x ≤ 0.7) photocatalysts have a monotonous enhancement of the H2 evolution rate against the increasing x value. With a 3 wt% Ru-cocatalyst, the photocatalytic performance of Ca0·3Sr0.7Ga2O4 was enhanced 1.8-folds by comparing with the intrinsic one. Although the sample has a photo-corrosion in 10% triethanolamine (TEOA) solution during the hydrogen production reaction, the hydrogen evolution amounts maintain stably for every 5 h in the total 100 h of the cyclic experiment. These semiconductors before and after photocatalysis were analyzed by X-ray techniques.

Tailoring of efficient electron-extracting system: S-scheme g-C3N4/CoTiO3 heterojunction modified with Co3O4 quantum dots for photocatalytic hydrogen evolution

• g-C 3 N 4 /CoTiO 3 S-scheme heterojunction was successfully designed and prepared. • Co 3 O 4 quantum dots were uniformly and tightly attached to the surface of the heterojunction. • The integration of S-scheme/promoter realized an efficient electronic-extracting system. • The hydrogen evolution performance of the ternary nanoreactor exceeds the binary system. Enhancing the utilization rate of photogenerated electrons has been considered as one of the bottlenecks in obtaining efficient photocatalytic hydrogen production system. This work deals with Co 3 O 4 quantum dots (CDs) modified S-scheme g-C 3 N 4 /CoTiO 3 (CN/CTO) heterojunction as a photocatalyst for water splitting. The S-scheme heterojunction retains a good carrier separation, and the built-in electric field also endows vigorous driving force for charge transport. CDs can be used as the electron acceptor, providing more active sites and achieving rapid capture of photogenerated electrons. The synergistic utilization of S-scheme structure and promoter considerably optimizes the electron transfer path, with enhanced spatial charge separation leading to more useful electrons with higher reducing capacity to participate in hydrogen evolution reaction. Using triethanolamine solution as sacrificial agent and eosin-Y as photosensitizer, the average H 2 evolution rate of optimized CN/CTO/CDs within 5 h of visible light irradiation was 1971.7 μmol g -1 h −1 , which was 102.7, 2.5 and 2.3 times higher than that of pure CN, CN/CTO and CN/CDs, respectively, with a corresponding apparent quantum efficiency was 3.39 %. Additionally, the charge transfer mechanism of S-scheme and the co-catalytic properties of CDs were further verified by the results of photoluminescence and photoelectrochemistry. This research contributes a valuable opinion for the integration of multicomponent photocatalytic systems.